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UK Wader Declines

New Study Reveals Links With Land Use

A new study, exploring the causes of population change in upland waders, has found that no single cause is connected with recent dramatic decreases in populations. Instead, research by the RSPB, suggests that different factors associated with varying land use may be influencing changes in certain species.

In the first Britain-wide assessment of its kind, the study looked at five wading bird species: lapwing, curlew, golden plover, dunlin and snipe. The study explored changes in their populations across various upland habitats.

It found that where declines had occurred, they were linked with factors such as habitat cover, forest-edge exposure, grouse moor management intensity and crow abundance.Wading birds are often found on areas of damp, wet moorland and rough grassland, feeding on worms and insects in the soil. Waders were once a common sight on farmland and uplands, regularly cited in literature and complimented for their evocative calls and charismatic behaviour. However, in recent decades, these birds have suffered dramatic population declines in many areas. The Repeat Upland Bird Survey carried out by the RSPB suggested declines of over 50 per cent of lapwing, dunlin and curlew over the last 25 years in many parts of the British uplands.

These losses have prompted further investigation by conservationists to try to identify the reason behind them. Using data from these past upland bird surveys, RSPB scientists, with support from Scottish Natural Heritage, were able to analyse changes in the abundance of waders from almost 1500 sq kilometres across the UK’s uplands (from Exmoor to the north of Scotland), examining whether population changes could be linked to variations in land use, such as the amounts of nearby forestry, or the intensity of grouse moor management.

Results, published in the international scientific journal Bird Study, found that numbers of golden plover and snipe, declined more in upland landscapes where there was more forestry in surrounding areas.The exact causes for this relationship are not known, but waders breed on the ground and as such are vulnerable to predation. The surrounding forest may well be beneficial to nesting crows or foxes, which are the main predators of eggs and chicks of upland waders. Other recent studies have shown that changes to upland wader abundance can be influenced by numbers of predators, and this study suggests that afforestation, in some areas, might be an important factor behind this relationship.

Declines in lapwing numbers were greatest in areas dominated by heather. For this species, links to predation were also identified. Regionally, lapwing populations fared better on areas with more intensive grouse moor management (a management practice involving predator control and heather burning) and worse where there was high crow numbers. The same was not true, however, for golden plover, which surprisingly suffered greatest declines in areas where grouse moor management was more intensive.Dr Murray Grant, a principal conservation scientist with RSPB, said:“The decline of uplands waders has been a cause for concern for a number of years, particularly as the reasons for these changes were not clear cut. These are birds that many people will recognise and were commonplace three or four decades ago. This new research provides useful indicators on which factors might be important in driving declines in these splendid birds. The next task will be to use this information to dig a little deeper and determine the mechanisms for the declines and what we can do to help these species on areas where decreases are greatest.”

Professor Des Thompson for SNH commented: "This research shows the complex nature of changes in our wader populations in the uplands, including vividly revealing the decline in curlew and lapwing numbers. Many people working in the uplands lament the loss of these birds, so we do need to intensify our understanding of what is happening - and then try do something about it."

4th July 2014