Designing wader landscapes

blog whimbrelMuch has been written about the negative impacts of agriculture on breeding birds – but farming can be good for some species. In Iceland, where high-input agriculture is relatively recent, breeding waders are commonly found in nutrient-rich environments that are associated with increased production. How can high breeding densities of waders be maintained, as farming continues to expand and intensification increases?

In her paper in Agriculture, Ecosystems & Environment Lilja Jóhannesdóttir investigates the distribution of breeding waders across landscapes with varying amounts of highly-cultivated fields and semi-natural areas. She discovers that, in some circumstances and at an appropriate level, adding cultivated land within a broader mosaic of habitats may benefit breeding waders. Is this a model system that provides clues as to how to design landscapes that can support sustainable breeding wader populations in other parts of the world?

The waders of Iceland

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Breeding populations of waders in Iceland (AEWA report)

Iceland is a hot-spot for breeding waders, holding half or more of Europe’s Dunlin, Golden Plover and Whimbrel, in a country that is a bit smaller then England. The paper at the heart of this blog is written by Lilja Jóhannesdóttir, who worked with colleagues from the University of Iceland, the Agricultural University of Iceland, the University of East Anglia (UK) and the University of Aveiro (Portugal). They investigated how different ways of increasing agricultural productivity might impact upon these species, and others such as Black-tailed Godwit, Redshank and Snipe.

Much of Iceland’s upland interior is not suitable as farmland but there is still plenty of room for agricultural expansion. Only 7% of the area between sea level and an elevation of 200 m is currently under cultivation but it is estimated that it would be possible to increase this to 63% – an eight-fold extensification. Icelandic lowlands currently comprise a fine-scale mosaic of open semi-natural habitats and cultivated fields (primarily for silage production to feed animals), making most of the landscape much more heterogeneous than in countries with a longer history of commercial farming.

blog hay and semi-naturalTwo previous WaderTales blogs have already shown that:

Given that farm production is predicted to increase, that farmers like breeding waders and that some intensively-managed fields can be attractive to waders, is it possible to design farmed landscapes that will work for birds and farmers?

Increasing inputs and reducing heterogeneity

blog nice wetlandGlobally, the expansion and intensification of agriculture has altered landscapes and the associated homogenisation has greatly influenced bird abundance and reduced biodiversity. Populations of numerous species, particularly specialist species, have declined, as agriculture has expanded, while generalist species have often thrived in agricultural habitats.

There is no shortage of examples in which highly intensively managed farmland is shown to be bad for breeding waders. In the monoculture hay-meadows of the Netherlands, Black-tailed Godwit productivity is really low, for instance. These fields have been drained, fertilised and re-sown, in order to create easily-managed carpets of single-species grass that can be cut several times a year. There is more about this in this paper by Roos Kentie.

blog hay fieldAlthough there are some areas of Iceland in which farming is quite intensive, there are many others where farmers have a lighter touch. For instance, nutrient-poor dwarf birch marshes may occasionally be grazed by sheep in the summer but these areas have never received applications of artificial fertiliser. At this end of the intensification continuum, increasing agricultural operations may have benefits for breeding waders. When a patch of rough grazing is ploughed and turned into a hay meadow, the addition of fertilisers can potentially increase soil fertility and create an attractive place for waders to feed. A hay meadow within a local area that is dominated by dwarf birch marsh could effectively increase the heterogeneity (& nutrient-richness via spill-over) of the local area, albeit in an artificial way. In the UK, Golden Plovers breeding on moorland are known to travel up to 7 km to feed on fertilised hayfields with high earthworm densities. This paper by James Pearce-Higgins & Derek Yalden in IBIS provides a nice example of how low intensity agriculture can provide resources for waders in the wider landscape.

Researching waders and landscapes

blog dbmLilja’s work in the Southern Lowlands of Iceland focused upon understanding how agriculture influences breeding wader densities and how these relationships might influence future change. At its heart were counts of adult waders encountered along 200 transects (totalling over 100 kilometres) within semi-natural habitats, visited at several stages during the breeding seasons of 2011 and 2012.

As well as counting birds, Lilja categorised habitats within 500, 1000, 1500 and 2500 metres of the transects, which she called buffer area in the paper. Interestingly, and usefully for later analyses, the distribution of different habitat types is pretty uniform across these scales, in this part of Iceland, with little substantial difference according to elevation. In the diagram below, the 200 transects (a) have been split between those below 50 m above sea level (b) and those higher than 50 m (c).

buffers

Landscape-scale effects

To fulfill the various demands of parents and their offspring, waders need diverse resources on or near their territory. An adult can feed a kilometre or more away from its nest, between incubation bouts, and chicks are mobile from an early age. Tagging has shown that young Black-tailed Godwits can move up to 3 km in the first five days of life, just to give one example. In this open landscape, breeding success is likely to be a function of habitat availability at a broad scale. This is explored in a WaderTales blog about nesting Whimbrel.

blog redshankUsing data collected from these 200 lowland transects, Lilja was able to establish relationships between breeding wader densities and the amount of cultivated land and wetland in the surrounding landscape. These two habitat types were considered because future agricultural expansion is likely to take place on drained wetlands that have high conservation value. In her analyses she assessed the extent to which the amount of cultivated land in the surrounding landscape affects wader densities on semi-natural land, and then considered the potential effects of future agricultural expansion on wader populations. There was substantial variation in the density of all of the six most common wader species recorded on the transects, ranging from 0 to 284 birds/km2.

Lilja found that wader densities in semi-natural habitats were consistently greater when the surrounding landscapes had more wetland, at scales ranging from 500 m to 2500 m, indicating the importance of wetland availability in the local neighbourhood. However, the effects of cultivated land in the surrounding landscape varied with fertility and landscape structure, which was largely defined by altitude.

  • In fertile, low-lying coastal areas (from sea-level to 100 m altitude), wader numbers declined with increasing amounts of cultivated land (and the lowest densities occurred in areas dominated by cultivation). This suggests that further conversion of semi-natural habitats into farmland is likely to severely impact waders in low-lying areas.
  • In less fertile habitats at higher altitudes (between 100 m and 200 m), the lowest densities occurred in areas without cultivated land. This suggests that additional resources provided by cultivated land may have a more positive affect in the less-fertile, higher altitude areas.

blog blackwitThe relationships between the areas of wetland and agriculture in the surrounding landscape and the density of waders vary between species, as you can read in some detail in the paper. A few highlights are:

  • With increasing area of cultivated land, densities of Golden Plover, Dunlin and Whimbrel declined significantly at lower altitudes but increased at higher altitudes. These are the three species that would appear to respond most positively to the addition of pockets of cultivated land within a semi-natural matrix of less fertile land, that tends to be found at higher elevations.
  • Higher amounts of wetland were associated with increased densities of Dunlin and Black-tailed Godwit, but lower densities of Redshank. Golden Plover numbers were unaffected by amount of wetland in the surrounding landscape.
  • Whimbrel densities increased with wetland area, at higher altitudes. Wet patches have been shown to be very important to Whimbrel chicks, as you can read in this WaderTales blog about research in Shetland.
  • At lower altitudes, Snipe densities increased with the amount of wetland area in the local vicinity. This relationship was less pronounced at higher altitudes, which tend to be less effectively drained and hence generally wetter.

dunlin graphic

What now?

Changes in Icelandic landscapes are to be expected in the coming years, as most farmers intend to increase their areas of cultivated land. This expansion will inevitably have impacts upon the internationally important breeding wader populations of Iceland but the level of such impact will depend on where the expansion will occur. This paper shows that increases in the area of cultivated land at lower altitudes in Southern Iceland are more likely to result in declines in wader density than in less fertile areas, when tend to occur at slightly higher altitudes (still under 200 m above sea level). An important next step will be to identify the landscape structures and scales of management that can continue to support high densities of breeding waders.

blog coastal wetlandGiven the international importance of Iceland as a home for breeding waders it would be nice to think that this paper can be used to develop national land management policies that can prevent the unintended loss of species such as Golden Plover and Snipe, which landowners value and wish to preserve. At the farm and community level, the paper highlights the key importance of maintaining the complex and heterogeneous landscapes of lowland Iceland, retaining as many as possible of the remaining wetland patches and pockets of semi-natural land within even the most intensive of farming areas.

The paper may well be of interest to conservationists who are struggling to reverse wader declines in other parts of the world. In Southern Iceland, where 7% of the land is being farmed relatively intensively within a fine scale mosaic of both wet and dry semi-natural habitats, it is possible to support hundreds of waders per square km across the wider countryside. Can this situation be replicated across large tracts of land in other countries?

Take home message and paper

blog heterogeneousThis paper provides a useful reminder that the links between land use changes and biodiversity implications can be highly context-dependent. Further agricultural conversion of wetlands and rough grazing areas in the fertile low-lying areas of Iceland is likely to be detrimental for breeding waders, but such effects may be less apparent in less fertile, higher altitude areas. Here, the conversion of some land from rough-grazing to hay meadows may provide feeding opportunities off-territory for Dunlin, Golden Plover and Whimbrel. The scale at which the addition of cultivated areas is beneficial to breeding waders has yet to be determined.

This paper is published as:

Interacting effects of agriculture and landscape on breeding wader populations. Lilja Jóhannesdóttir, Jennifer A. Gill, José A. Alves, Sigmundur H. Brink, Ólafur Arnalds, Verónica Méndez and Tómas Grétar Gunnarsson https://doi.org/10.1016/j.agee.2018.11.024

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GFA in Iceland

Graham (@grahamfappleton) has studied waders for over 40 years and is currently involved in wader research in the UK and in Iceland.  He was Director of Communications at The British Trust for Ornithology until 2013 and is now a freelance writer and broadcaster.

 

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Tool-kit for wader conservation

andyhayDecades of drainage and agricultural intensification have caused huge declines in numbers of breeding waders in the lowland wet-grasslands of Western Europe. Although we were already well aware of these problems by 1995, and farmland prescriptions have been used to try to arrest the declines since then, we have still lost nearly half of Britain’s breeding Lapwing in the last twenty years. Even on nature reserves and in sympathetically-managed wet-grassland, it has proved hard to boost the number of chicks produced. Why is this and what else is there that can be done?

bouThis is a summary of a presentation by Professor Jennifer Gill of the University of East Anglia and Dr Jen Smart of RSPB, delivered at the BOU’s Grassland Workshop (IOC Vancouver, 2018).

There are five key techniques in the tool-kit used by conservationists trying to support breeding waders:

  • Make the site attractive to waders
  • Manage predator numbers, particularly through lethal control
  • Manage habitat structure to make alternative prey available
  • Exclude predators, either permanently or temporarily
  • Invest in head-starting chicks, to boost productivity

Size of the problem

redshankThe decline in wader numbers in England has been happening for a very long time. In just the period 1995-2016, Lapwing numbers have fallen by a further 26% and Redshank numbers by 39%, according to Bird Trends, produced by BTO & JNCC. Within the English lowlands there has been a dramatic contraction into nature reserves, especially in the east of England.

The Breeding Waders in Wet Meadows survey showed that fields that are within nature reserves are much more likely to be occupied than other fields in wet grassland, particularly those that are included in wader-specific agri-environment schemes. The study is published in Ibis by Jen Smart et al.

smart 2014

Attracting breeding waders

Lowland wet grasslands in Broads

Creating shallow ditches. Mike Page/RSPB

Reserve managers and sympathetic landowners have become very good at creating the sort of habitats that attract breeding Lapwings. Autumn and winter grazing can be manipulated to produce short swards, whilst adding in shallow pools and foot-drains (linear features running through fields) increases feeding opportunities for chicks. See Restoration of wet features for breeding waders on lowland grassland 

The RSPB has invested heavily in time and equipment to deliver these lowland west grasslands, on their own land, on other nature reserves and on commercial farmland. By working with Natural England, they have helped to shape agri-environment schemes that can be used to deliver payments to farmers who are well-placed to create habitat that suits breeding waders.

Mark

wader pairsIn the east of England, there are now more than 3000 hectares of this attractive, well-managed wet grassland habitat, designed to be just right for species such as Lapwing. The graph alongside, drawn using RSPB data, shows the number of pairs of Lapwing (green), Redshank (red) and other waders (Oystercatcher, Avocet & Snipe: blue) in Berney Marshes RSPB reserve in eastern England for the period 1986 to 2016. There were early successes, as new areas were purchased and transformed, but growth in wader populations has not been sustained, despite ongoing improvements in land management. What is preventing further recovery?

Demographic processes

survivalIn a paper in the Journal of Ornithology, Maya Roodbergen et al  used demographic data collated across Europe to show that there had been long-term declines in nest survival and increases in nest predation rates in lowland wader species. One of the main focuses of management action at Berney Marshes is to maximise Lapwing productivity but nesting success is still below 0.6 chicks per pair in most years (see graph), which is the minimum estimated productivity for population stability (Macdonald & Bolton). Not enough chicks are being hatched, with the vast majority of egg losses being associated with fox activity.

Controlling foxes

The obvious solution for breeding waders must surely be to shoot foxes? It’s not that simple. In a multi-year, replicated experiment to assess the impact of controlling foxes and crows, RSPB scientists showed that there were no clear improvements in wader nesting success; effectiveness is very much site-specific. Much may well depend on how much fox control there is in the surrounding area.

foxIf fox impacts cannot be reduced sufficiently through lethal control, perhaps it is possible to reduce their effects on waders by understanding the ways in which foxes forage and to adapt the habitat appropriately? Work by Becky Laidlaw and others has shown that Lapwing nest predation rates are lower close to tall vegetation and in areas with complex wet features. However, Becky has also shown that management to create these features, even in areas of high wader density and effective predator mobbing, is only likely to achieve small reductions in nest predation. There is a WaderTales blog about this: Can habitat management rescue Lapwing populations?

Excluding foxes

malpasOne solution to the fox problem that does work is to exclude foxes (and badgers) from an area, by using electric fences. See paper by Lucy Malpas (now Lucy Mason). Fences may be deployed at different scales; just around individual nests, temporarily (around individual fields) or permanently (around larger areas).

  1. Nest-scale may be most appropriate for species such as Curlew, which have large territories and do not nest colonially. Finding nests is time consuming but relatively small lengths of fence could potentially be erected during the incubation period.
  2. Whole-site protection will suit semi-colonial species such as Lapwing. Although expensive to install, permanent fences can require relatively little maintenance and can potentially be powered by mains electricity. One disadvantage may be that the presence of large numbers of chicks can attract avian predators, such as birds of prey, which are themselves conservation priorities and hence difficult to manage.
  3. fence 2Field-scale fences usually rely on batteries, which need to be checked and changed, and fences need maintenance, as the grass grows and can short out the bottom strands. However, deployment at the field-level allows for dynamic use within a farming landscape and in accordance with agri-environment schemes. New research by RSPB and the University of East Anglia aims to see if fences need only to be deployed for relatively short periods. If pairs nest synchronously then groups of birds may be able to maintain the ‘fence-effect’ by mobbing predators, when a temporary fence is removed.

Head-starting

morgan 2018Although it might be possible to improve the habitat that is available for breeding waders and to reduce predation pressure, it is sometimes too late to boost numbers – simply because populations have shrunk to too low a level. At this point, head-starting (rearing chicks from eggs) may be appropriate. This blog celebrates the success of the first year of a joint initiative by RSPB and WWT (Project Godwit) to increase the local population of Black-tailed Godwits in the East Anglian fens: Head-starting Success.

In conclusion

In trying to boost breeding wader populations, land-managers and conservationists have developed techniques to increase site attractiveness and reduce predator impacts, through management, control and exclusion. The tools that are used will depend upon species, budget and conservation priorities.

This work was presented by Jennifer Gill & Jen Smart at a BOU symposium on the Conservation of Grassland Birds, in Vancouver, August 2018.

Blog adultWaderTales blogs about Lapwings and Redshanks

The work of RSPB and University of East Anglia scientists features strongly in these blogs, which focus on support for breeding wader populations in lowland wet grassland and on coastal saltings.


GFA in Iceland

WaderTales blogs are written by Graham Appleton (@grahamfappleton), who  has studied waders for over 40 years and is currently involved in wader research in the UK and in Iceland.  He was Director of Communications at The British Trust for Ornithology until 2013 and is now a freelance writer and broadcaster.

 

 

Scottish Wader Woes

The report on Scotland’s terrestrial bird species, covering the period 1994-2016, does not make easy reading for wader lovers. All but one species is contributing negatively to the upland bird indicator, with declines of over 40% for breeding Lapwing, Curlew, Dotterel, Oystercatcher and Golden Plover. In this short blog, there are links to information that helps to explain what might be going wrong for Scotland’s waders.

The full report is available on the SNH website (https://www.nature.scot/information-library-data-and-research/official-statistics/official-statistics-terrestrial-breeding-birds)

One species has been increasing – Snipe up 22%

snipe abundance changeThe one spot of good news is that breeding Snipe numbers in Scotland have risen over the period 1994 to 2016. This is particularly encouraging, given declines in much of the rest of Britain and Ireland, as you can see in the map alongside and read in this WaderTales blog Snipe and Jack Snipe in the UK and Ireland.

In the map, produced for Bird Atlas 2007-11 (BTO, BirdWatch Ireland & SOC), pink colours show abundance increases and grey areas show decreases.

Lapwing declines largest – down 63%

GHH pictureWhen a widespread species such as Lapwing is in decline this is bad news. Subtle difference in the way that lowland valleys are farmed may be part of the problem, as illustrated in this WaderTales blog, based on work by Mike Bell, written up with the help of John Calladine, of BTO Scotland: 25 years of wader declines.

Curlew down 62%

Blog Jill PThe Curlew is causing huge concerns in Ireland and Wales, where conservationists are contemplating its disappearance as a breeding species. Scotland holds much larger numbers but a decline of nearly two-thirds suggests that there are major problems here as well.

Two WaderTales blogs tell the Curlew story. Is the Curlew really near-threatened explains why we should be so worried about what is happening and Curlews can’t wait for a treatment plan summarises a BTO-led paper from Sam Franks and colleagues which attempts to explain the patterns we are seeing in the species’ decline.

Dotterel down 60%

IMG_2123

Alistair Baxter

Most of the information about Scotland’s breeding birds comes from annual data collected by volunteers contributing to the Breeding Bird Survey (BBS), organised by the BTO, in partnership with JNCC and RSPB. Dotterel is different; here the counts are dependent on dedicated surveys of Scotland’s high-mountain plateaus. Concern for the species is very much linked to climate change but this blog, based on a paper by the RSPB’s Daniel Hayhow and colleagues, shows that there may well be other reasons for the species decline: UK Dotterel numbers have fallen by 57%. The figure for the decline may be slightly out-of-date but the blog isn’t.

TGG OycOystercatcher down 44%

In England, the latest BBS report shows an increase of 50% in Oystercatcher numbers but, in Scotland, where there are far more breeding pairs, the species is in decline. Oystercatchers: from shingle beaches to roof-tops looks at the history of the species’ spread from the shoreline, into the hills and onto roofs and considers the role of predation in recent declines.

Golden Plover down 43%

As noted in the press release about the new report ‘The golden plover population has declined by 43% since 1994 and stands at its lowest point since the BBS survey began. Declines may be linked to climate change, in part due to impacts on the abundance of craneflies during the breeding season. There are two interesting papers about this by James Pearce-Higgins and colleagues.

golden ploverPearce-Higgins, J.W., Yalden, D.W. & Whittingham, M.J. 2005. Warmer springs advance the breeding phenology of golden plovers Pluvialis apricaria and their prey (Tipulidae). Oecologia 143: 470–476.

Pearce-Higgins, J.W., Dennis, P., Whittingham, M.J. & Yalden, D.W. 2010 Impacts of climate on prey abundance account for fluctuations in a population of a northern wader at the southern edge of its range. Global Change Biology 16: 12–23.

Common Sandpiper down 39%

The Breeding Bird Survey does not properly capture trends for species found mostly along rivers. Data for Common Sandpiper are derived from the BTO Waterways Bird Survey and the Waterways Breeding Bird Survey.

Why no Redshank?

Unfortunately, breeding Redshank are now patchily distributed across Scotland, with too few being picked up by BBS surveyors to make a contribution to Scottish population indices. Across the UK, the latest published BBS decline is 38%. UK graphs for Oystercatcher, Redshank and Curlew are shown below.

UK BBS


GFA in Iceland

WaderTales blogs are written by Graham Appleton, to celebrate waders and wader research.  Many of the articles are based on previously published papers, with the aim of making wader science available to a broader audience.

@grahamfappleton

 

Farming for waders in Iceland

Across the world, agriculture is one of the primary threats to biodiversity, as we tear up natural environments to create more space to feed an ever-growing and increasingly meat-hungry human population. Agricultural land can, however, also provide key resources for many species whose behaviours align with the rhythms of the farming year.

blog cows

In Iceland, farming areas support large and important populations of several wader species, including 75% of Europe’s Whimbrel and over half of Europe’s Dunlin. As the country welcomes more tourists and expands the range of crops grown for food and fuel, what might be the implications for iconic species such as Whimbrel, Dunlin and Black-tailed Godwit?

This paper by Lilja Jóhannesdóttir, of the University of Iceland, and colleagues there and at the universities of Aveiro (Portugal) and East Anglia (UK), investigates the use of farmland by waders living in a semi-natural landscape.

Paper details: Use of agricultural land by breeding waders in low intensity farming landscapes Lilja Jóhannesdóttir, José A. Alves, Jennifer A. Gill, & Tómas Grétar Gunnarsson Animal Conservation. doi:10.1111/acv.12390

A dynamic landscape

blog snipe postIn Iceland, volcanic activity poses serious short-term threats to agriculture, especially in areas close to the mid-Atlantic ridge, which runs through the island from south-west to north-east. Threats from volcanoes include ash-fall, lava, flooding of glacial rivers and earthquakes but, on the plus side, nutritional inputs from volcanoes have beneficial effects on soil fertility in these central areas. Over time, and with the assistance of wind and water, many of these nutrients collect in the lowlands of the country – the areas that now form the main agricultural areas, especially in the warmer south.

The distribution of breeding waders varies across lowland Iceland. A survey carried out between 2001 and 2003 showed that wader densities were greater in areas of the country that had been subject to higher rates of volcanic ash deposition with, for instance, three times as many waders in the south as in the west. See How volcanic eruptions help waders. As was shown in the paper at the heart of that blog, the nutrient signal associated with ash-fall breaks down in farmland. Here, perhaps as a consequence of the application of natural and artificial fertilisers over decades or even centuries, there is no association between ash-fall and wader density. Across the whole country, irrespective of the proximity of volcanoes, nutrient-rich agricultural land attracts waders – but which wader species and across which farmland habitats?

Waders and agriculture

In a previous paper, Lilja Jóhannesdóttir showed that over 90% of Icelandic farmers think it is important or very important to have rich birdlife on their estates, but that farmers also expect to increase the area of farmed land in the coming years. There’s more about this in the WaderTales blog: Do Iceland’s farmers care about wader conservation? It is important to understand the ways that waders currently use farmland, in the hope that nesting waders can continue to be accommodated within the future farming landscape of Iceland.

blog oyc bare

Perhaps Oystercatchers think that the fields have been ploughed especially for them?

Agriculture in Iceland is still relatively low in intensity and extent, and internationally important populations of several breeding bird species are abundant in farmed regions. Only about 2% of land is cultivated (about 7% of lowland areas), of which about 85% is hayfields (grass fields managed to produce crops of grass for storage as winter feed) and 15% consists of arable fields (mostly barley). This is similar to areas such as Norway, northern Canada and northern and western areas of the British Isles but contrasts sharply with the US and many countries in the EU which, on average, have 20% or more of their land under cultivation.

In these high-latitude landscapes, agricultural land can potentially provide resources that help to support wader species. To address these issues, Lilja conducted surveys of bird abundance on 64 farms in northern, western and southern areas of Iceland that vary in underlying soil productivity, and quantified:

  • Levels of breeding bird use of farmed land managed at three differing intensities, ranging from cultivated fields to semi-natural land
  • Changes in patterns of bird use of farmed land throughout the breeding season.

Farm survey

In Iceland, there are still large patches of natural or semi-natural habitats; they surround the hay-fields and arable fields that are at the heart of many farms. This arrangement creates gradients of agricultural intensity from the farm into the surrounding natural land, tapering from intensive management to moderate and light management.

BLOG gradient

The three intensity levels within Icelandic farmland can be roughly described as follows:

  • Intensive: Hayfields (85%) and arable fields (15%) fields. Most hayfields are mown twice per year and ploughed and reseeded every few years.
  • Moderate: Old hayfields that are rarely or never mown but are used for grazing, or fertilized grasslands used for livestock grazing.
  • Light: Semi-natural or natural areas under low intensity grazing, usually by sheep or horses, or with no agricultural influence, ranging from sparsely vegetated habitats to habitats with abundant vegetation (where grasses and bushes dominate the vegetation) and with a broad wetness gradient.

Fields corresponding to these three categories were surveyed on the 64 farms, firstly during the egg-laying and incubation period and then later, to coincided with chick rearing.

blog 3 habitats

Gradient of management from intensive (left) to wet semi-natural (right)

Where were the waders?

blog RK on postLarge numbers of waders were encountered in all transects in all parts of Iceland, with Black-tailed Godwit and Redshank contributing most records. There were also important numbers of Oystercatcher, Golden Plover, Dunlin, Snipe and Whimbrel. Overall, wader densities on farms did not vary significantly between regions or between early and late visits but there were some subtle differences:

  • Wader density varied significantly along the management gradient, with lower densities tending to occur in more intensively managed areas, particularly in the early (nest-laying and incubation) season.
  • Intensively managed fields in the west (where underlying soil productivity is lower) had higher densities of waders than in the north and south of the country.
  • There were seasonal declines in wader density on all three management types in the south, but seasonal increases on intensive and moderate management in the west and in fields under moderate management in the north.
  • There were some differences between species in these patterns (more details in paper).

blog redshank westOne of the interesting differences in the west was the redistribution of Redshank as the season progressed. There were three times as many pairs of Redshank in cultivated land during the chick-rearing period than during incubation, suggesting that adults may be moving broods into cultivated land. Resources for chicks may well be relatively more abundant or accessible in these areas, given the relatively low levels of nutrients in areas that are a long way from the active volcano belt. There’s also a suggestion that drainage ditches around cultivated fields in the west may provide important resources for Snipe.

What about the future?

blog distributions

Wader densities during the early (red) and later (blue) part of the breeding season (Modified from the paper in Journal of Animal Conservation)

Although the density of birds in Iceland’s agricultural landscapes tends to be higher in lightly managed than intensively managed agricultural land, densities in the areas under the most intense agricultural management are still high, suggesting that agricultural habitats provide important resources within these landscapes (see figure alongside). These density estimates (between 100 and 200 waders/km2) are typically much higher than those recorded in other countries in which these species breed.

Farmers in Iceland expect to expand their cultivated land in the coming years in response to increasing demand for agricultural production (Do Iceland’s farmers care about wader conservation?), and evidence from other countries throughout the world has shown how rapidly biodiversity can be lost in response to agricultural expansion and intensification. Protecting these landscapes from further development is crucial to the species that they support.

The authors suggest ways in which farming practises might change wader distributions in Iceland. Here are a few of the interesting points that they make:

  • When wader-rich semi-natural land is replaced by arable farming and intensively-managed hayfields, this is likely to reduce overall wader densities.
  • Losing wet features, which provide insect food for waders, may well have impacts for chick growth. Here’s a WaderTales blog that discusses the importance of wet features to Lapwings in the UK.
  • In other countries, early grass mowing is a direct threat to nests and chicks. Clutch and brood losses are already being observed in Iceland and, with warmer springs encouraging earlier grass growth, this could become more of a problem.
  • The conversion of less-intensively managed areas into farmland is likely to have most effect on Dunlin, Black-tailed Godwit and Whimbrel, which tend to occur in their highest densities in the least intensively managed lowland areas.

blog walk WhimbrelIt is estimated that between 4 and 5 million waders leave Iceland each autumn, for Europe, Africa and the South Pacific (Red-necked Phalarope). Iceland’s farmland supports many of these birds and this study highlights the need to protect them from the agricultural developments that have led to widespread wader losses throughout most of the world.

You can read the paper here

Use of agricultural land by breeding waders in low-intensity farming landscapes Lilja Jóhannesdóttir, José A. Alves, Jennifer A. Gill, & Tómas Grétar Gunnarsson. Animal Conservation. doi:10.1111/acv.12390

blog oycs & chick

 


 GFA in Iceland

WaderTales blogs are written by Graham Appleton, to celebrate waders and wader research.  Many of the articles are based on previously published papers, with the aim of making wader science available to a broader audience.

@grahamfappleton

 

 

25 years of wader declines

This article summarises a Bird Study paper arising from a 25-year Scottish study of breeding Lapwing, Oystercatcher, Redshank & Curlew. The story is set against a backdrop of a changing farming landscape.

RC LapThe interesting and sobering feature of this paper about breeding waders by Mike Bell and John Calladine is that its focus is a ‘normal’ area of farmland in Scotland. If you’ve taken the A9 north of Stirling, through Strathallan, then you’ll have driven past the fields. Perhaps you might even have noticed displaying Lapwing, Oystercatcher, Curlew and Redshank? Over a 25-year period, the number of breeding waders in this valley and another one that runs northwest and that can be seen from the B827 has dropped from 600 pairs to just 76 – that’s a loss of 87%, or over 20 pairs per year.

So, what has changed in this part of Scotland that might be linked to these declines? The authors conclude that the reduction in numbers can be linked to changes in field management. Put simply, there are too few bare fields in the spring for Oystercatcher (down 95%) and Lapwing (down 88%). These two species hide their nests in ‘plain site’; they watch out for predators, take off early and hope that the eggs are coloured cryptically enough to avoid detection. Having left their nests, they attempt to deter and/or distract prowling crows etc.  Redshanks (down 87%) and Curlew (down 67%) have also declined, even though they hide their nests in long grass, about which more later.

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Lapwing declines in the Strathallan area are not that much different to those that have been charted across much of Britain & Ireland

In for the long haul

In a survey in the late 1980s, this area of Strathallan held an important assemblage of farmland breeding waders, with particularly high densities of nesting Lapwing. Land use in the valley is predominantly agricultural, with a mixture of arable fields and grazing by sheep and beef cattle. It is a relatively open landscape with few hedgerows, some scattered shelter belts and small conifer plantations.

KS RedshankThis study started in 1990, when breeding densities of nesting Oystercatcher, Lapwing, Redshank and Curlew in the core area were still high, at 11.7, 35.6, 4.7 and 3.3 pairs/km2 respectively. Unlike a PhD project, which might include three years of data, Mike Bell has kept this survey going for 25 years. Mike is the volunteer Regional Representative for the British Trust for Ornithology’s Perthshire region.

Breeding waders within a core area of 65 fields and a small amount of wet fen were surveyed annually from 1990 to 2015. The field sizes were small, by modern standards, with only five fields larger than 20 ha. An additional 1 km2 of lowland mixed farmland was surveyed in most years, 4 km2 of moorland rough grazing was surveyed in four years and another 5.3 km2 of enclosed and unenclosed rough grazing and moorland was surveyed at the beginning and end of the survey period only.

Land management and usage were recorded for each field on the first visit in April or early May. Spring sward height in each field was recorded as one of three categories: no vegetation, short (<10 cm) or long (>10 cm). These sward categories comprised the following field types:

  • bare – ploughed or tilled land with no emergent vegetation
  • short – managed grass for grazing or mowing for hay or silage, rough grass, rush pasture, spring arable, setaside/fallow.
  • long – managed grass, rough grass, rush/pasture, setaside/fallow, heath/moorland, marsh/wetland, unmanaged rank grassland and woodland/scrub.

Where to find waders in Strathallan

In the early 1990s, Strathallan supported around 36 Lapwing pairs/km2 across the core study area, which is comparable with some of the highest densities reported anywhere in the UK. During the 25-year study, as the numbers of Lapwing, Oystercatcher, Redshank and Curlew declined, an increased proportion of the remaining breeding waders became restricted to areas with fields classed as ‘bare’ in spring, while the greatest losses were in fields with ‘short’ and ‘tall’ spring sward heights (see figure).

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Changes in breeding densities of waders in Strathallan, on fields with different sward heights

Breeding densities of Curlew were low throughout the study area and, although overall numbers declined, there was low power to detect statistically significant changes. There were different patterns of change for Lapwing, Oystercatcher and Redshank within fields of different spring sward heights:

  • The least marked changes were in fields with no vegetation in spring.
  • Fields with short swards showed the largest declines.
  • The tallest spring sward heights supported the lowest densities of the three wader species, with Redshank present generally at low densities in all vegetation categories.
UK BBS

UK-wide Breeding Bird Survey trends for Oystercatcher, Redshank and Curlew. BBS is organised by BTO in partnership with JNCC and RSPB.

A changing farmland landscape

Sward heights reflected changing farming methods. Looking at the fields in terms of cropping regimes.

  • The highest densities of Oystercatcher were in spring-sown arable crops.
  • Rush pasture was the most favoured field type for Lapwing and Redshank at the start of the study but the amount of this habitat declined during the study, as farmers created semi-permanent pastures for over-wintering sheep. When this happened, birds became more restricted in their nesting distribution.
  • By 2015, very few fields were still under a crop rotation of grass and spring arable, that would have delivered a mosaic of sward structures. By this time, half of the Lapwing pairs were nesting in just four fields.

Breeding success

The breeding success of Lapwings was estimated in five sample fields that could easily be observed from roads or tracks without disturbing the adults. Lapwing productivity was less than 0.60 young fledged/pair (the bench-mark for a typical stable population) in all but three years and it was less than 0.25 young fledged/pair in 14 of the 22 years. With very low recruitment rates, it is not surprising that the Lapwing is in decline.

There are several WaderTales blogs about Lapwings breeding in lowland wet grassland, including A helping hand for Lapwings. A full list of WaderTales blogs can be found here.

What is changing?

TGG Oyc

The changing fortunes of Oystercatcher are discussed in this WaderTales blog

Within a mixed arable-pasture farmland environment, bare field and short swards in spring appear to be important to breeding waders. Losses of these preferred habitats type don’t appear to fully account for the decline in numbers, however.

Alongside changes to farmland habitats, other potential factors that could have contributed to the decline of the wader population in Strathallan include an increased incidence of poor spring weather, increased disturbance (including from dog-walkers in some fields in some years) and an increase in predators. Mike Bell thinks that one of the reasons for a possible link between productivity declines and wet weather is that birds are nesting in sub-optimal (long) grass and hence more affected by wetter conditions. He writes about this and potential reasons for increased disturbance in an upcoming article in Scottish Birds. A link to the Scottish Birds article will be included when available.

Densities of avian predators increased in Strathallan during the study period, with higher breeding densities of Carrion Crow and Buzzard and an increasing frequency of bigger flocks of non-breeding crows. There was no detectable change in breeding success during the study but it is possible that nest success was already depressed by predation when the study commenced.

A relentless decline

GHH pictureAlthough previously identified as a good area for breeding waders, in a Scottish context, there is nothing unique about this Strathallan study area. It is good to see these issues explored in Bird Study, the BTO journal. I am sure that the editor, Ian Hartley, will have been pleased to publish a paper based on a nice mix of dedicated fieldwork and scientific analysis – that’s what the BTO is all about.  If you want to understand the (not yet fully explained) sad demise of breeding waders in Scotland, check out the figures in the paper. These show a relentless, 25-year decline in nesting densities across a range of habitats and some less-than-subtle changes in the way that fields are now managed.

Here’s a link to the paper:

The decline of a population of farmland breeding waders: a twenty-five-year case study by Michael V. Bell & John Calladine in Bird Study, 64:2, 264-273 DOI: 10.1080/00063657.2017.1319903


 GFA in Iceland

WaderTales blogs are written by Graham Appleton, to celebrate waders and wader research.  Many of the articles are based on previously published papers, with the aim of making wader science available to a broader audience.

@grahamfappleton

 

 

Interpreting changing wader counts

Blog mixed flockWhen you count the number of Redshank on your local estuary and discover that there are fewer now than there were last year –  or five, or twenty years ago – what are the implications? Is this part of a national or international trend or has something changed within the estuary itself?

The first question to ask is, ‘what is happening elsewhere?’ and then to wonder about the ways in which numbers of birds in different sites might relate to each other. What actually happens to local counts when national counts go down – or go up, for that matter?

The UK Wetland Bird Survey (WeBS) data provide comprehensive and long-term monitoring of estuarine wader populations around our coastline. Thanks to volunteers who collect monthly counts each year, these data present an excellent opportunity to explore how bird distributions can change over time. A new paper by Verónica Méndez and colleagues from the University of East Anglia and British Trust for Ornithology uses counts of 19 species (18 waders plus Shelduck, an honorary wader) over a 26-year period to ask what happens to distribution and local abundance across our estuaries when overall population sizes go up or down.

Consequences of population change for local abundance and site occupancy of wintering waterbirds Verónica Méndez, Jennifer A. Gill, José A. Alves, Niall H. K. Burton & Richard G. Davies Diversity and Distributions. 2017;1–12. DOI: 10.1111/ddi.12653

The counters

Blog Counter 2A WeBS count can be a tough assignment for a volunteer birdwatcher. Being allocated to a stretch of an estuarine coastline and asked to visit it, whatever the weather, on a given weekend of every month, in every winter, is not the same as an invitation to go birdwatching in September to look for a Curlew Sandpiper.

The counts used in this paper are from the months of November through to February, when waders are largely settled for the winter and the weather can be less than clement. Many of the data-points for individual sites have been collected by the same person in all of the years analysed in the paper and every contribution is important.

WeBS70logo6a_smallWeBS is the successor of other, similar count schemes which are celebrating 70 years of continuous monitoring this year. It is organised by BTO, in partnership with RSPB and JNCC and in association with WWT. There are over 3000 registered WeBS volunteers, collecting data about the waterbirds that can be found on estuaries, in wetlands, on inland lakes, along river valleys and in local parks and villages.

Understanding change

Many populations of migratory birds are changing in number quite rapidly at present, but are these changes more likely to result in changes in occupancy (eg colonisation of or extinction from some sites) or changes in abundance within sites? Put simply, if extra waders arrive in the autumn, how do they distribute themselves across available sites? If fewer arrive, where will the gaps be found?

DN and BTG graphs

The contrasting fortunes of Dunlin and Black-tailed Godwit over the period covered in the new paper

Over the period studied in the paper (between 1980-85 and 2002-07), populations of five species declined, with the greatest losses occurring in Purple Sandpiper and Shelduck (both declined by about 25%), while there were increases for four, the biggest of which were Avocet (+1690%), Golden Plover (+554%) and Black-tailed Godwit (+418%). No birdwatcher will be shocked by the figures for Avocet or Black-tailed Godwit, wintering numbers of which have shot up, but Golden Plover is more of a surprise and may be linked to a move from inland fields to estuaries.

When the size of a wintering population of waders declined, Verónica Méndez and her colleagues found that the main consequence was a reduction in numbers across all sites. Birds were likely to stay on a site even if local numbers were dwindling. This suggests high levels of site-fidelity by individual waders, which is something we know from ringing and tracking studies. If you’re still alive then just do the same again – there could be a better site with a higher number of conspecifics somewhere else but it would be risky to try to find that out.

 

Blog Avocets

Thirty years ago, few people can have expected that they would ever see such a large flock of Avocets on the Humber

If the size of a wintering population increased, generally numbers went up within all occupied sites. The exceptions tended to occur in species for which original numbers were very small, such as for Greenshank, or species for which the change in numbers has been rapid – as seen in Avocet and Black-tailed Godwit.

If adults don’t change their wintering sites then increases are presumably being driven by juveniles. Their settlement decisions may be influenced by the distribution of adults of the same species, resulting in increased local abundance, rather than colonisation of new sites. For the two rapidly-expanding species, Black-tailed Godwit and Avocet, there was colonisation of 25 and 15 new sites, respectively, between 1980-85 and 2002-07, with some indication of more similar increases in sites that were closer together, which may reflect local movements among groups of nearby sites.

Designating sites

Blog Blackwit

Juvenile waders may well settle in areas where there are already populations of wintering adults

One of the key conservation measures for waders across Europe is the Special Protection Area (SPA) network, a collection of sites that are designated because they hold internationally or nationally important numbers of species, measured as a percentage of the population. Designated sites need to maintain numbers of all the species that hit this threshold percentage. However, if a national or European population gets larger (for example because of high breeding success) but the number on a particular site does not grow (or grows more slowly), then the species might drop below the threshold for protection, even if the site is unchanged. Theoretically this could affect a site’s protected status for that species, although is unlikely to be a problem, as most sites are designated for many species.

This new paper shows that gains and losses tend to be fairly constant across all sites, making it unlikely that a site designation would be affected by national or European-scale changes. In only one species (Ringed Plover), have numbers declined so much in some sites that the total number of sites exceeding the threshold for that species has decreased.

Keep counting!

Blog Counter 1Habitat availability and site fidelity, along with species longevity, may explain the strong tendency for local population abundance to change much more than site occupancy, in our wintering waders. Given the statutory importance of maintaining waterbird populations in designated protected areas, it is important to continue local and national surveys that can identify changes in local abundance and relate these to large-scale processes.

Returning to the earlier question – When you count the number of Redshank on your local estuary and discover that there are fewer now than there were last year –  or five, or twenty years ago – what are the implications?

This new paper shows that it is unlikely that a local drop in a species’ numbers is caused by a redistribution of birds. Factors that might lie behind a local decline need to be investigated locally, if the trend is not replicated elsewhere. The authors could only reach this conclusion because they had 26 years of WeBS data from a range of sites at their disposal. Future generations of WeBS counters will hopefully continue to monitor the conditions of our estuaries, working together throughout the country to interpret local counts within a national framework.

Paper

Consequences of population change for local abundance and site occupancy of wintering waterbirds Verónica Méndez, Jennifer A. Gill, José A. Alves, Niall H. K. Burton & Richard G. Davies Diversity and Distributions. 2017;1–12. DOI: 10.1111/ddi.12653

Blog RINGOS


 GFA in Iceland

WaderTales blogs are written by Graham Appleton, to celebrate waders and wader research.  Many of the articles are based on previously published papers, with the aim of making wader science available to a broader audience.

@grahamfappleton

 

 

Wales: a special place for waders

From winter beaches to summer moorland and woodland, Wales provides essential habitats for waders. 

welsh-header

There are over forty WaderTales blogs so far. Here’s a selection that may well appeal to birdwatchers in Wales.

Winter beaches & estuaries

AA

Most Oystercatchers are being ringed with two letter engraved rings, along with two colour-rings: Photo Tómas Gunnarsson

Wales holds important populations of waders in the wintertime – everything from Bar-tailed Godwits from Siberia to Turnstones from Canada. Some of the Oystercatchers seen in sites such as the Burry Inlet or the Menai Strait are from Iceland, where they can be found alongside Redshanks and Golden Plover that have also arrived from the north. They emphasise the close links between Wales and Iceland when it come to birdlife.  Migratory decisions for Icelandic Oystercatchers explains how a new project is examining the costs and benefits of being a migrant. Welsh reports of Icelandic colour-ringed birds are helping to provide answers.

Here’s where Oystercatchers that breed or were raised in Iceland have been reported across Britain & Ireland:

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snipe-1Interestingly, while there are similar links between Ireland and Iceland, the migratory provenance of Welsh Snipe may be very different to that of Irish ones. A quarter of foreign-ringed Snipe reported in Ireland have been found to be wearing Icelandic rings but, so far, no Reykjavik-ringed Snipe have been spotted in Wales. Snipe & Jack Snipe in the UK and Ireland compares the migratory strategies of the two species and laments the decline of Common Snipe, as a breeding species.

Protecting key wintering sites is a high priority when it comes to wader conservation. A recent BTO and WWT project aims to provide better information as to how species as diverse as Dunlin and Shelduck make use of the Severn Estuary. This is important work, with major relevance to discussions as to how power might be generated within the estuary. Tracking waders on the Severn urges birdwatchers to look for colour-marked birds. Initial results, shared at the recent International Wader Study Group conference, indicate that the home range of a Redshank is ten times as big as originally thought. It will be interesting to see what else this study reveals.

horse-and-flockHundreds of Welsh birdwatchers take part in the Wetland Bird Survey and the intensive work involved in periodic Low Tide Counts. These identify and monitor key sites and establish the most important feeding sites within estuaries. Whilst mud  and sand-flats are, of course, important to waders, so are roost sites. A place to roost discusses the importance of safe, high-tide roosts, especially in terms of energetics. I had not realised that it has been estimated that the cost of flying to and from roosts might account for up to 14% of a bird’s daily energy expenditure. That’s something to think about next time you see a dog chasing off a flock of roosting waders.

Passing through

whimbrel-mig-fig1There is exciting work going on in Wales to understand why so many Whimbrel spend time in the country in the spring. Whimbrels on the move summarises a recent paper about the movements of Icelandic, ringed Whimbrel. Since its publication, a new paper has shown that Whimbrel are able to fly between Iceland and west Africa in one jump but that they sometimes need to stop off on the way north. See Very rapid long-distance sea crossing by a migratory bird by José Alves and colleagues.

There’s a blog on the subject of wader migration if you want a quick summary for 40 or more species: Which wader, when and why?

Breeding Waders

Wales provides homes to many breeding waders, from Ringed Plover on the coast, via Little Ringed Plover and Commons Sandpiper along rivers and into the moorland for Curlew and Dunlin, passing a forest with Woodcock en route. And that’s only giving a mention to half of the country’s breeding wader species.

CattleStarting on salt-marsh, Big-foot and the Redshank nest investigates appropriate cattle stocking levels for successful Redshank breeding. Although the work was undertaken in northwest England, there is no reason to believe that Welsh cattle area any less careful as to where they put their feet. There are several other blogs about Lapwings and Redshank on the WaderTales site.

We are all aware of the issues facing upland waders. The next blog was written to promote a survey in England, looking at the distribution of waders along the moorland/farmland interface, but the stories will have resonance with Welsh birdwatchers. All downhill for upland waders outlines changes to breeding numbers and distributions of waders breeding in England’s uplands.

Curlew e (2)

Curlews fly vast distances to spend the winter on the estuaries of Britain & Ireland (© Graham Catley)

Is the Curlew really near-threatened? considers the plight of breeding Curlew. It’s easy to understand why RSPB, BTO, GWCT and BirdWatch Ireland are focusing on this species How long will it be until breeding Curlew are lost from Wales, completely?

This blog summarises the threats to breeding Curlew across Great Britain: Curlews can’t wait for a treatment plan.

Research by RSPB in Wales has focused on specific issues relating to grazing: Sheep numbers and Welsh Curlews.

Predation is acknowledged as a major issue for Curlew but is this going to be a problem for Oystercatchers too? Oystercatchers: from shingle beach to roof-tops reveals a significant decline of the species in Scotland, mediated to some extent by range expansion in three dimensions. There’s a specific mention of the Burry Inlet control programme of the 1970s.

The strangest Welsh wader has to be the Woodcock – probing about in winter fields and nesting in forestry plantations. Conserving British-breeding Woodcock focuses on worrying results from the latest GWCT/BTO survey and work to reduce losses during the shooting season.

Further reading

Hopefully, this summary  gives a flavour of some of the issues being faced by Welsh waders and the research to which they are contributing. There are already over 40 blogs in the WaderTales series, with one or two new blogs being produced each month. If you want to know more about wader migration or moult, how volcanoes affect breeding waders in Iceland, why Black-tailed Godwits wear colour-rings or if there are costs to carrying a geolocator have a look here.


GFA in IcelandGraham (@grahamfappleton) has studied waders for over 40 years and is currently involved in wader research in the UK and in Iceland.  He was Director of Communications at The British Trust for Ornithology until 2013 and is now a freelance writer and broadcaster.

Can habitat management rescue Lapwing populations?

Can a mosaic of habitats boost hatching success in grassland-breeding Lapwings?

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Lapwings are becoming more and more restricted in their distribution within the United Kingdom, with an increasing proportion dependent on a small number of lowland wet grassland sites, particularly nature reserves. Working in this habitat, a team from the RSPB and the University of East Anglia has been trying to work out if it is possible to substantially improve Lapwing productivity without using intensive, costly predator management, in the form of permanent electric fences.

Background

graphThe RSPB has been monitoring breeding waders on their Berney Marshes reserve in Norfolk for over 20 years. Even with fox control, a wader-friendly grazing regime and sensitive regulation of water levels, Lapwing nesting success on this site is still below 0.6-0.8 chicks per pairs in most years, which is the estimated range required for population stability (Macdonald & Bolton 2008a). Predation is the main issue that is still limiting productivity.

Previous work has shown that:

  • Providing areas of tall, dense grass (often along field verges) can encourage populations of small mammals, which are the main prey of most wader nest predators (Laidlaw et al 2012).
  • The lay-out of wet features can influence Lapwing nesting densities (Eglington et al 2008).
  • Nest survival is higher when Lapwing densities are higher (Macdonald & Bolton 2008b).

The team believe that these three factors – small mammal distribution, surface water and Lapwing nesting density – are very likely to influence the behaviour and distribution of red foxes, the key predator in this study area.

There is more background information in the WaderTales blog entitled A Helping Hand for Lapwings and in a perspectives article in Wader Study by Jen Smart.

ditchIn a recent RSPB/UEA project, Dr Becky Laidlaw has investigated these relationships further and has then used the trends that have been established to model different potential management scenarios. What could happen if nesting densities, wetness and the proximity of verges with small mammals could all be varied in the best ways possible? Is there a theoretical scenario in which productivity is high enough to fuel population growth?

The paper is published as: Scenarios of habitat management options to reduce predator impacts on nesting waders. Rebecca A. Laidlaw, Jennifer Smart, Mark A. Smart and Jennifer A. Gill 2016 Journal of Applied Ecology doi: 10.1111/1365-2664.12838

The right habitat mix?

Using relationships established from previous studies and collating seven years of information on over 1400 individual nesting attempts, Dr Becky Laidlaw and her colleagues from UEA and RSPB saw that, not only was nesting success being influenced by wetness and the proximity of tall grass, there were some subtleties relating to the way that habitats are distributed. Might it be possible to  redesign the site so as to create a patchwork that could achieve the required productivity levels? Becky had two variables to play with – verges and wet features.

Verges influence predation rates, with Lapwing nests further from tall vegetation areas having a higher likelihood of being predated. This makes sense if foxes are concentrating on catching small mammals in areas with high mammal densities, and are more likely to ignore eggs that are laid in short grass close to mammal-rich verges.

proper-wet

There are plenty of wet features at Berney. The River Yare is in the foreground.

Water also influences wader nest predation rates. This is not surprising; if you are a fox, it is probably going to be harder to search for nests in a wet field with lots of pools and ditches than in a dry field. Interestingly, the study found that nests in the centre of dry fields were more at risk than those at the centre of wet fields. In a wet field, it’s riskier to nest along the edge, whilst in a dry field the risk increases the further the nest is from the edge.

wet-v-dry-graph

Part of a figure in Scenarios of habitat management options to reduce predator impacts, published in Journal of Applied Ecology by Laidlaw et al (Journal of Applied Ecology, 2016)

chicks

The team want to see more Lapwing chicks. These are newly-hatched.

The study confirmed that isolated Lapwing nests are more at risk of predation, potentially because single pairs don’t benefit from the mobbing defensive behaviour provided by having plenty of nesting neighbours. They found a similar pattern with Redshank nest predation risk; these scarcer breeding waders appear to be protected by the presence of more Lapwing.

Scenario modelling

Becky then worked with Mark Smart, the RSPB manager with responsibility for Berney Marshes, to model some potential future management scenarios for the site. They worked out where it would be feasible to add or remove verges and increase or decrease surface wetness within fields. Becky then used existing relationships to predict what changes in nest predation rates might be expected. Were there management options that could significantly increase survival rates of nests?

ralphBecky compared the different modelled management scenarios with the long term average nest predation rate for the site. She found a significant (roughly 20%) reduction in nest predation could potentially be achieved with the addition of tall vegetation, but only for nests close to field edges in areas of high Lapwing nest density. Importantly, this sort of decrease in nest predation levels could potentially increase the number of chicks hatching by around 100 each year, but such management relies upon areas of sufficiently high Lapwing breeding density being available.

The influence of nesting density

The aim of this applied research was to find a way to manage breeding habitat for Lapwing that could be rolled out to areas of conservation-sensitive farming outside nature reserves. Given the subtleties of creating the right patchwork of wet features and long grass at Berney, it’s going to be tricky to get similar benefits on other sites. If habitat management alone is not enough, even when used alongside fox control, then what else can be done?

Becky has a possible answer. “The breeding density measure we are using is the number of active nests within 100 metres of a nest. It may therefore be important not only for nests to be clustered in fields with appropriate conditions, but also that they are at the same stage at the same time. Synchronous nesting is something that we think might be very important.”

fenceFrom data collected on RSPB reserves with and without electric fences (which exclude foxes), it is clear that fencing greatly increases the synchrony of nesting attempts (because most of the early nesting attempts are successful). Given that the density of active nests has a major effect on nest survival rates, increasing the number of nests active at the same time may well provide a greater level of protection, through the mobbing behaviour of Lapwing, and therefore lead to greater hatching success.

As part of a new piece of research (funded by NERC, a UK government research council), Becky and the UEA/RSPB team are going to test whether the provision of temporary electric fences for just the early part of the breeding season can provide sufficient protection to increase hatching success, as a consequence of nests being more synchronous. If early-reared chicks are more likely to fledge than late-reared chicks, there also may be additional knock-on benefits post-hatching and through to the recruitment stage. This work is taking place in RSPB’s Yare Valley reserves and at Carlton Marshes (Suffolk Wildlife Trust).

Becky is hopeful. “We understand how wader predation rates are influenced by the proximity to verges, the accessibility issues caused by water and the mobbing, defensive behaviour of waders. We are now interested in determining the best way to use this information in management. With the new work with fences we’re going to be specifically exploring the importance of synchrony to both nest success and productivity”.

Scenarios of habitat management options to reduce predator impacts on nesting waders. Rebecca A. Laidlaw, Jennifer Smart, Mark A. Smart and Jennifer A. Gill 2016 Journal of Applied Ecology doi: 10.1111/1365-2664.12838

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GFA in IcelandGraham (@grahamfappleton) has studied waders for over 40 years and is currently involved in wader research in the UK and in Iceland.  He was Director of Communications at The British Trust for Ornithology until 2013 and is now a freelance writer and broadcaster.

 

Big Foot and the Redshank Nest

What’s the crunch point? Grazed saltmarsh is an important habitat for Redshank but the addition of an extra four large feet can have serious negative effects. 

Cattle top adam cross

Each grazing unit comes with four very large feet (Adam Cross)

In a 2016 paper in Agriculture, Ecosystems & Environment, Elwyn Sharps and colleagues from Bangor University, CEH and the RSPB have shown that there is a tricky balance between providing the open, grazed habitats in which Redshanks can breed and minimising the likelihood of nests being trampled by cattle. If only cattle could do their important habitat management work outside the nesting season? However, the grass keeps growing and these four-footed, saltmarsh mowing machines usually arrive on site in spring and stay throughout the summer.

Sharps, E., Garbutt, A., Hiddink, J. G., Smart, J., & Skov, M. W. (2016). Light grazing of saltmarshes increases the availability of nest sites for Common Redshank Tringa totanus, but reduces their quality. Agriculture, Ecosystems & Environment, 221, 71-78. 

Background

small_00206RKBH19702011_010_0

Distribution map from Bird Atlas 2007-11, which is a joint project between BTO, BirdWatch ireland and the Scottish Ornithologists’ Club

In the United Kingdom, Redshanks are amber listed species of conservation concern, increasingly restricted in their distribution. The map alongside shows that breeding Redshanks have been lost from many areas (downwards pointing black arrows). More distribution maps from Bird Atlas 2007-11 can be found on the BTO Mapstore.

Although they breed in various grassland habitats, coastal saltmarshes are internationally important. The breeding population on British saltmarshes has reduced by over 50% since 1985. Declines have been linked to grazing management, as breeding densities are higher with light and moderate grazing than on heavily grazed or ungrazed saltmarshes (Norris et al., 1998; Malpas et al., 2013).

Intensive grazing leads to a very short, uniform sward, lighter grazing produces a more uneven patchy sward with diverse heights whilst no grazing can leave saltmarshes with dense communities of coarse grasses. For Redshank, which need clumps of grass in which to hide their nests and more open areas in which chicks can feed, light grazing is a key management tool.  Elwyn Sharps and his colleagues, working on the saltmarshes of the Ribble Estuary in northwest England, were interested to see just how light a grazing regime worked for the local Redshanks.

CattleWorking on the Wash, nearly twenty years previously, Ken Norris and colleagues had found that breeding densities were higher in structurally diverse grazed vegetation, and recommend low stocking densities of about 1 cattle ha-1, in order to create a patchy vegetation sward, suitable for nesting Redshank. This falls within the UK Environment Agency definition of light saltmarsh cattle grazing of between 0.7 and 1 young cattle per hectare between April and October, which translates to an annual cattle density of 0.3 to 0.5 cattle per hectare per year.  Work on the Ribble suggests that light grazing can reduce nest survival both directly through nest trampling and indirectly through accelerating predation risks. Breeding densities may appear high in some areas but productivity can still be very low.

An earlier paper by Elwyn Sharps et al. showed that the risk of Redshank nest predation increased from 28% with no grazing to 95% with grazing of 0.5 cattle per hectare per year, which is still within the definition of light grazing. Some of the nest failures were due to trampling, with 1 out of 5 nests being affected in areas with the lowest stocking rates and 4 out of 8 in the most heavily stocked (though still defined as lightly-grazed) area.

What do Redshank need?

Trampled egg christine tansey

Crunch point: when a large foot meets a fragile clutch (Christine Tansey)

In lowland wet grasslands, Jennifer Smart demonstrated that Redshank select tall nest vegetation, with some additional cover in a wider 10m area around the nest. Elwyn Sharps investigated nest site selection by Redshank breeding in six lightly grazed saltmarshes around the Ribble in with cattle densities were between of 0 to 0.55 grazing units ha-1 y-1.  In May and June 2012, a total of 45 Redshank nests were found across the six saltmarshes (between 5 and 10 nests per marsh) and vegetation heights and species composition were measured at and in the vicinity of nests, as well as at control points.

Redshank nest christine tansey

Christine Tansey

On The Ribble, vegetation height was taller at, next to and in the wider area around nests, when compared to control points, for all spatial scales studied, in line with those found on lowland wet grasslands. The vegetation composition was different in the immediate vicinity and in the wider area around nests than at control points, indicating that Redshank select nest sites surrounded by particular species of vegetation. Most of the dissimilarity between nests and control points was due to red fescue (Festuca rubra), which was more abundant near nests than at control points. There is a suggestion from the Ribble data that Redshank select nests within communities of F. rubra, which is a species associated with cattle-grazing in higher elevation saltmarsh.

Implications for land management

_DSC2219Redshank

Not quite long enough? Redshank nests are often completely hidden withing clumps of grass (Kevin Simmonds)

The results of this study suggest that livestock grazing plays an important role in creating the F. rubra nesting habitat preferred by Redshank nesting on the Ribble Estuary. However, even low intensity conservation grazing can create a shorter than ideal sward height, potentially leaving Redshank nests more vulnerable to predators. Translating the UK Environment Agency light grazing guidelines of 0.7-1 young cattle per hectare between April and October to measurements used in this study would mean an annual cattle density of around 0.4-0.5 cattle per hectare per year, which this study suggests is too intensive for breeding Redshank.

Elwyn Sharps suggests that future solutions should focus on designing grazing regimes which increases sward heights for Redshank nesting. This could include delaying the start of grazing until most Redshank stop nesting in mid-July, but then grazing more intensively afterwards. This would allow vegetation to remain tall during the nesting season, but would still maintain a cover of F. rubra.

IMG_3993

To read more about RSPB studies of breeding Redshanks visit this WaderTales blog (Kirsty Turner)

Another potential management solution may be a rotational grazing system, whereby saltmarshes are grazed and left ungrazed in alternate years, potentially improving habitat quality by allowing the vegetation to grow taller in the ungrazed year. However, on a small scale, Redshank may then select the part of a saltmarsh that was previously ungrazed , and therefore the area that will soon be grazed. It is clear that there are a number of possible solutions to this problem that require further investigations if the ideal saltmarsh management option for Redshank is to be ascertained. In working out how to manage saltmarshes for breeding waders, land managers will need to take account of the needs of other breeding species, overwintering wildfowl, and wider saltmarsh biodiversity, each of which may apply different constraints.

Sharps, E., Garbutt, A., Hiddink, J. G., Smart, J., & Skov, M. W. (2016). Light grazing of saltmarshes increases the availability of nest sites for Common Redshank Tringa totanus, but reduces their quality. Agriculture, Ecosystems & Environment, 221, 71-78.

And another problem…

In a more recent 2017 paper in Ecology & Evolution, Elwyn Sharps and colleagues show that cattle spend their time in the same areas of a saltmarsh as the ones in which Redshanks like to nest. Their conclusion is that “grazing management should aim to keep livestock away from redshank nesting habitat between mid-April and mid-July, when nests are active, through delaying the onset of grazing or introducing a rotational grazing system”.

Nest trampling and ground nesting birds: Quantifying temporal and spatial overlap between cattle activity and breeding redshank.


 GFA in Iceland

WaderTales blogs are written by Graham Appleton, to celebrate waders and wader research.  Many of the articles are based on previously published papers, with the aim of making wader science available to a broader audience.

@grahamfappleton

 

 

All downhill for upland waders?

 

Are targeted payments for England’s upland farmers benefiting Curlew, Lapwing, Oystercatcher, Redshank and Snipe?

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The farmed land that fringes our moors provides important habitats for breeding waders (Dawn Balmer)

In the period 1995 to 2013, England lost 32% of its breeding Curlew, 31% of its Redshank, 27% of its Lapwing and 14% of its Snipe*, according to the latest Breeding Bird Survey results. The uplands are the main stronghold for Curlew and hold (or used to hold?) significant numbers of the other three declining species. Is the story one of total gloom or are there areas where sensitive farm management and agri-environment payments are successfully supporting waders and other species associated with upland farms? A new survey, funded by Defra and coordinated by BTO aims to find some answers.

* Please note that the figures for population changes have not been updated. They all relate to the period 1995 to 2013. Latest figures can be found by following the link to the BBS results (see above).

The snappily-titled Breeding Waders of English Upland Farmland survey starts in April and volunteers are still needed in many areas. Please visit the BTO website if you may be able to help.

More about the key species:

curle 004 (nest) (Derek Belsey) (A)

Derek Belsey

Curlew (recent 32% decline in England). The species is globally defined as near-threatened and has been added to the red list of conservation concern in the UK. Losses have been particularly severe in Ireland, Northern Ireland and Wales but the distribution is shrinking in England. There’s a WaderTales blog about Curlew here. Is the Curlew really ‘near-threatened’?

Lapwing (recent 27% decline in England). Most of the work to try to understand recent declines in Lapwing numbers has been undertaken on lowland wet grassland, where cooperative mobbing of predators is an important part of the daily routine for parents. In the uplands, where breeding densities are lower, it would not be surprising if predation pressures could be impeding species recovery. There are two WaderTales blogs about these issues. A helping hand for Lapwings and How well do Lapwings and Redshanks grow?

redsh 058 e (Jill Pakenham) (A)

Jill Pakenham

Redshank (recent 31% decline in England). The situation for Redshank is very similar to that for Lapwing, the presence of which may help in predator defence. There is a WaderTales blog about the special issues in the Uists (NW Scotland), where introduced hedgehogs are causing huge problems in this key wader hot-spot. Prickly problems for breeding waders

Snipe (recent 14% decline in England). The survey methods used in the new BWEUF survey are not designed to detect Snipe, which are mostly active at dusk, but the visits should provide useful count and distribution data for an under-researched species.

oyste 066 e (Nigel Clark) (A)

Nigel Clark

Oystercatcher (recent increase of 56% in England). Much of the increase may well be occurring in river valleys and newly created wetlands and gravel pits, rather than in the uplands. We know from the recent Moorland Forum report Understanding Predation that there have been changes in Oystercatcher abundance in much of upland Scotland between 1990 and 2010, potentially linked to predation pressure. It would not be surprising if similar processes operate in the English uplands.

How the BWEUF survey will work

Breeding wader populations in the UK have been a major conservation priority for some years. Declines continue despite the implementation of conservation measures that are designed to deliver appropriate habitats, some of which are supported through agri-environment schemes (AES). While enhanced monitoring of many upland and lowland habitats would be valuable, a particular gap is evident for in-bye farmland. This habitat can be defined as juncus/rush pastures, semi-improved pastures and meadows below the moorland line, although it technically includes all enclosed farmland. Using Defra funding, Natural England has commissioned BTO to run a volunteer-based survey, with RSPB field-staff filling gaps in less accessible areas.

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Photo: Dawn Balmer

This project will assess the importance of in-bye land for waders, by estimating the total numbers present in these habitats, relative to national estimates measured from Bird Atlas 2007-11 data. More importantly, it will set a baseline against which to measure future change in breeding numbers.  This will be used to assess the success of Environmental Stewardship management, as well as to measure differences in numbers between AES and non-scheme habitats for waders that nest and/or forage on in-bye farmland. The survey will use 2×2km grid squares (tetrads), as in Bird Atlas 2007-11. Volunteers are asked to make two morning visits to each tetrad, one between early April and mid-May and a second before mid-July, with a minimum of a two-week gap between visits. On each visit, volunteers will be asked to survey as many as possible of the fields in this in-bye buffer of 1km below the moorland line. They will walk to within 100m of every part of each field to which they have access, recording all birds seen and heard, noting any display or territorial behaviour and mapping the locations of target wader species.

yelwa 015 e (Jill Pakenham) (A) (2)

There’s an opportunity to record other species of conservation concer, such as this red-listed Yellow Wagtail (Jill Pakenham)

The key features of grassland management and structure, along with other land use, which dictate suitability for waders, will be recorded.  Predation has been identified as one potential driver of population decline – or an impediment to species recovery – so observers will be asked to record avian and non-avian predators.

Birdwatchers do not normally spend much time in this in-bye habitat so here’s an opportunity to capture as much information as possible, especially for any other waders and gamebirds (Black Grouse, Grey Partridge, Pheasant, and Red-legged Partridge). Valuable information can be data can be collected for Cuckoo, Linnet, Meadow Pipit, Reed Bunting, Ring Ouzel, Skylark, Stonechat, Twite, Wheatear, Whinchat and Yellow Wagtail, many of which are red-listed species of conservation concern (and bonus birds on a day’s birdwatching). To view further information on survey methodology follow this link.

In Summary

The wader declines quoted in this article use Breeding Bird Survey data from 1995 but there is evidence of longer-term falls for Curlew (55% since 1975), Lapwing (65%), Redshank (65%) and Snipe (90%). These are worrying numbers and it is to be hoped that the BTO can find enough volunteers for BWEUF, despite the fact that many of the survey squares are a long way from the flat-lands in which most English birdwatchers live. Curlews, Lapwings, Oystercatchers, Redshanks and Snipe are counting on us to count them.


 GFA in Iceland

WaderTales blogs are written by Graham Appleton, to celebrate waders and wader research.  Many of the articles are based on previously published papers, with the aim of making wader science available to a broader audience.

@grahamfappleton