Sheep numbers and Welsh Curlew

This paper from Ian Johnstone and RSPB colleagues, in the BTO journal Bird Study, provides some interesting evidence as to how the distribution of breeding Curlew in Mynydd Hiraethog (North Wales) relates to habitat. Amongst other things, they conclude that the amount of sheep grazing is critical to the future recovery of the species in this area.

Correlates of Distribution and nesting success in a Welsh upland Eurasian Curlew population by Ian Johnstone, Dave Elliot, Chris Mellenchip & Will Peach. Bird Study https://doi.org/10.1080/00063657.2017.1411466

The bigger picture

Internationally, the Eurasian Curlew is designated as near-threatened because of the rapid declines in numbers across the species’ range. Irish conservationists are worried that the species may soon disappear as a breeding species and Welsh birds may not be many years behind, if the current population trajectory continues. For more background see this WaderTales blog: Is the Curlew really near-threatened?

While conservation measures such as ‘habitat improvement’ and ‘predator control’ are already being used in specific recovery projects it is still important for scientists to use current evidence to tease apart the factors that may be affecting the distribution and breeding success of Curlews. An earlier WaderTales blog, summarising a paper by Sam Franks and colleagues from BTO and RSPB, concludes that habitat changes and predator impacts have combined to cause declines and lists some of the specific factors involved. Across Great Britain, they found that semi-natural grasslands support the highest densities of Curlew and population declines were highest in areas with more crows and foxes. See this WaderTales blog: Curlews can’t wait for a treatment plan.

The Curlews of Mynydd Hiraethog

Looking down from the moorland of Hiraethog into intensively manged farmland in the valley

Mynnydd Hiraethog is a discrete 150 km² upland block of high grass and heather moorland with adjacent lower, enclosed and largely agriculturally improved farmland. The area is managed for livestock farming and forestry and nearly half of the moorland was designated as a Site of Special Scientific Interest (SSSI) in 1989 because of the importance of its upland habitats for birds. The mountains of North Wales have long been grazed by sheep, with peak densities occurring in the Hiraethog region in about 1999. Agreements with farmers have reduced stocking levels, in order to enable overgrazed habitats to recover.

This study focuses upon the relationship between habitat variables and Curlew numbers in a landscape containing agriculturally improved farmland and moorland that was partly protected and subject to grazing reductions for nature conservation. Thirty, random 1 km squares, stratified by historical population trend, were surveyed for Curlew density and nesting-success. Habitat-related and predation-related variables such as ground cover, plant communities and crow numbers were collected to test for associations between Curlew distributions and environmental variables.

Curlew numbers in the study area declined by 29% between 1994 and 2008, which is much lower than the decline of 46% across the whole of Wales in the same period (Breeding Bird Survey). By studying a mix of squares in which Curlew numbers had increased, remained stable and declined, the researchers were able to maximise the power of the tests. As expected from previous studies, densities in the moorland edge were higher than in improved farmland (there’s plenty of detail in the paper). There were fewer Curlews in areas with higher vegetation density, with 78% of pairs in survey squares with below-average ground cover. In dense cover, prey may be harder to detect and access.

By focusing on key plant species that are associated with particular habitat types, the team were able to identify links with Curlew abundance and nesting success. As predicted, they found that breeding abundance was positively related to the presence of mat-grass Nardus stricta, which grows as tussocks and is associated with rough grazing. Nesting success was higher in areas with more cover of deer-grass Trichophorum germanicum, a sedge that is found in bogs and on wet moorland. Blanket mires are known to support populations of surface invertebrates, which are particularly important to chicks.

Woodland may provide look-out perches and nesting habitat for avian predators and den-sites for foxes and other studies have shown that waders are less numerous close to woodland, either because of a direct predation effects or because waders avoid areas of perceived danger (as discussed in this WaderTales Blog – Mastering Lapwing Conservation). There was only weak evidence of reduced Curlew abundance in areas with more woodland in the Hiraethog area. Fox and crow control takes place across the whole area (for livestock protection) so there was insufficient variation to look at any effects that predator numbers may have on distribution or breeding success.

What next for Curlews?

On Hiraethog, much of the rough grazing, characterised by Nardus stricta, and mire, characterised by Tricophorum germanicum, is contained within the SSSI, and the RSPB authors affirm that these habitats should continue to receive protection from developments such as agricultural intensification and tree planting.

Curlews preferentially occupy locations within the moorland/farmland edge. Historically there has been concern over impacts on upland breeding waders of high sheep grazing pressure but more recently worries have been expressed over under-grazing of some upland habitats in Wales. In Hiraethog, the fact that fewer breeding Curlews were found in areas of dense vegetation is consistent with under-grazing having potentially contributed to a decline in habitat suitability.

Welsh moorland, with blanket bog in the foreground and a mosaic of grassland in the background

There was a 46% drop in sheep numbers in Hiraethog between 1995 and 2009, according to figures from Natural Resources Wales, in order that priority habitats would recover from historical overgrazing. This reduction in grazing pressure has probably resulted in increased vegetation density and reduced sward suitability for Curlew. Vegetation density was higher inside the SSSI than in comparable habitats outside, particularly for habitats preferred by Curlew such as heath and rough grazing.

The authors recommend that management of the SSSI for Curlew should include increases in livestock grazing of appropriate type and intensity.  These should be targeted at rough grazing and mire, in areas that have a history of Curlew occupation and that have high current vegetation density. It is hoped that modest and localised increases in grazing pressure can reduce vegetation density without negatively impacting on protected habitats. If successful, and implemented in an experimental manner, then similar treatments may well be trialled elsewhere.

The full paper can be accessed here

Correlates of Distribution and nesting success in a Welsh upland Eurasian Curlew population by Ian Johnstone, Dave Elliot, Chris Mellenchip & Will Peach. Bird Study https://doi.org/10.1080/00063657.2017.1411466

---

 

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.

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

In 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.

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.

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.

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

Where were the waders?

Large 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).

One 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?

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.

It 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

 

---

 

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

 

 

International Shorebird Rescue

Huge numbers of birdwatchers and conservationists across the globe are involved in shorebird/wader conservation.  It all starts with noticing that numbers are changing, then you need to work out why species are in decline, before suggesting ways to treat the problem and monitoring what happens afterwards. The whole process can be regarded as ‘International Shorebird Rescue’ and anyone who takes part in systematic counts of waders is part of the team. 

This blog is based upon the plenary presentation that launched the global BOU Twitter conference on 28 and 29 November 2017. You can see the rest of the presentations here, storified on the BOU website. In this talk, entitled International Shorebird Rescue, I tried to highlight the role of shorebird scientists and volunteers in the conservation process.

A Twitter talk is a series of tweets delivered within an allocated time-slot, each of which is usually accompanied by ‘slides’ providing more detail. In this blog, I have allowed myself a few more than 140 (or even 280) characters, to try to make the links a little smoother. The first slide, showing all of the speakers, was produced by Steve Dudley, the BOU’s Chief Operations Officer.

I introduced myself and WaderTales to the BOU audience, explaining that I have been studying waders for 40+ years and that my current focus is science communications, particularly via WaderTales blogs, a full list of which is available at https://wadertales.wordpress.com/about/

“International Shorebird Rescue” celebrates the role of wader researchers and birdwatchers in conservation. I describe shorebird rescue as a four-stage process – notice there is a problem, diagnose what it is, start a treatment plan and monitor what happens.

Shorebird conservation is fuelled by the passion of researchers and policy-makers. I could have chosen many other excellent people to exemplify the way that ‘waderologists’ engage in conservation.

Shorebird conservation is not easy because many populations rely on a complex suite of sites during the course of a year. Migratory species such as this Marbled Godwit in North America face different conservation challenges in different seasons. There’s  more about the threats faced by the numeniini in this WaderTales blog. Why are we losing our large waders?

Migratory movements of waders were not always well understood. Here’s an example from the 1970s, when shellfishery interests in Wales conflicted with conservation interests in Norway. 

How science can inform policy

Thankfully, wader conservation is now more joined-up. In the next few slides I show how counts & scientific papers turn into conservation policy, using the Black-tailed Godwit as an example.

Black-tailed Godwits have been experiencing contrasting fortunes, with declining numbers of the limosa subspecies and increases in islandica. These two WaderTales blogs provide background:

Dutch Black-tailed Godwit numbers down by nearly 75%

Black-tailed Godwits expand their range in Russia and Iceland

By contrasting the different fortunes of the two subspecies, Black-tailed Godwit Species Action Plans were developed at an International Wader Study Group workshop and then published as a Wader Study paper, and by EU and AEWA. There are links to all three here: Wader Study paper, EU Management Plan and AEWA Action Plan. 

One of the common problems for declining wader populations at present is poor breeding success. For many species, productivity is too low for sustainable populations to persist, as discussed in this paper about demography.

Fencing – an effective treatment plan?

One of the emerging conclusions of recent research in the UK is that we need open discussion about reducing predator impacts on nesting shorebirds. One of the suggested approaches is to deploy electric fences, as in this paper by Lucy Mason (née Lucy Malpas). Lucy presented some of her more recent work later in session one of the BOU Twitter conference.

In which circumstances are fences effective and value-for-money?

How are fences deployed in  lowland wet grassland?

Fences are being used to try to reduce predation pressures on Curlew

The key role of estuaries

Estuaries are of vital importance to a whole range of wader species outside the breeding season. Here they face a multitude of threats, largely because ‘empty’ mudflats can be seen as being ripe for development. In the next few slides I have picked a selection of case studies in which an issue has been identified, data have been collected and conservation action has been proposed/implemented.

Waders have been losing mudflats for centuries, as exemplified on the Wash estuary, that sits between Lincolnshire and Norfolk in the east of England. The Wash was at its smallest in the 1970s. Recognition of the importance of the site has acted as a deterrent to planners, who might have claimed even more land for farming or created a large fresh-water reservoir.

A more recent physical threat is tidal power, as in the Severn Estuary, between England and Wales. Impact assessments have funded vital research in the area, as discussed in this blog.

The booming economy of Asia has put huge pressure on the Yellow Sea. Habitat removal is affecting annual survival rates and severely reducing populations of wader species that are most dependent upon the area. Fortunately, it is not too late to make a difference, as you can read here: Wader declines in the Yellow Sea

Conflict with fisheries is usually indirect but the reliance of shorebirds on the eggs of horseshoe crabs is turning the spotlight on fishing regulations in Delaware Bay. Effects of Horseshoe Crab Harvest in Delaware Bay on Red Knots; Are Harvest Restrictions Working?

Climate change threatens waders in the breeding grounds and on estuaries. Rising sea-levels and hard sea-walls are squeezing intertidal feeding areas.

Spoon-billed Sandpipers – true teamwork

As the presentation drew to a close, I wanted to finish with a positive story. Critically endangered Spoon-billed Sandpipers have a desperate need for International Shorebird Rescue and a huge amount of multinational effort is going into their conservation.

Head-starting Spoon-billed Sandpipers has been really successful, producing huge gains in productivity. This may be an important conservation tool for other threatened species, as exemplified in this WaderTales blog about Black-tailed Godwits in the washes of Eastern England.

Away from the Arctic, Spoon-billed Sandpipers face many challenges. The same bird may be impacted by habitat loss in the Yellow Sea during the autumn and by hunting pressure in Myanmar later in the winter.

Shorebird scientists are working with colleagues and policy-makers in China, S Korea and N Korea to save space for Spoon-billed Sandpipers in the Yellow Sea. (A more recent article by Nicola Crockford develops this story in Wader Study:

More game-changing good news on coastal wetland conservation – a policy perspective from the Yellow Sea to global conservation.

Quick mention of climate change

Much of current shorebird research is set in a context of climate change. Here’s a link to a blog about the change in timing of migration of Icelandic Black-tailed Godwits.

Notice > Diagnose > Treat

In the wader world , the time between ‘paper’ and ‘policy’ can be pleasingly short – because scientists and policy makers keep communication channels open, as has been demonstrated in the case of Yellow Sea.

 

‘International Shorebird Rescue’ works because passionate birdwatchers, scientists & policymakers work together. They operate within a system of international agreements that have been designed to protect migratory systems and the estuaries and wetlands upon which they rely.

This blog is based upon the plenary presentation that launched the global BOU Twitter conference on 28 and 29 November 2017. You can see the rest of the presentations by checking out #BOU17TC on Twitter or by visiting the BOU website.

This was a global Twitter conference, organised by the BOU (British Ornithologists’ Union – publishers of IBIS). It involved 70 scientists and science communicators from around the world, tweeting in their own time-zones for 26 hours. The BOU plays a pivotal role in ornithological communication and this was a great example of global cooperation – it does seem appropriate that ornithologists have taken to Twitter so readily!

---

 

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