Thread by @mattwridley

Thread. 1. As Natural England bans crow control at the behest of @ChrisGPackham, remember why curlews thrive mainly in the North Pennines. Controlled experiments showed that their success at fledging young went from 15% without predator control to 51% with predator control.

2. Curlews are declining all over Eurasia. Two species of curlew have already gone extinct: Eskimo curlew and probably the slender-billed. This vulnerability is because they are large, slow-breeding waders that rarely lay eggs before they are 3 years old.

3. The British Isles is the breeding heartland of the “common” curlew with nearly 30% of the world population nesting here. But they are now v scarce in Ireland and Southern England and rare even in some upland areas of the Lake District and much of Wales.

4. However, in one part of England they are so numerous that at this time of year their calls continuously overlap in the early morning – you cannot escape from their glorious, bubbling song even if you want to. This is the North Pennines.

5. There are as many pairs on a single small dale as in the whole of southern England. Why is this? The habitat is not necessarily better for them. The reason was discovered by the Otterburn experiment in the early 2000s conducted by the @GWCT

gwct.org.uk/research/scien…

6. In that experiment, 4 plots of 1200 ha each were monitored over 8 years. Two remained under the same management. One had gamekeepers controlling crows, foxes and stoats for 4 years, one had no gamekeeping. After four years these two plots were swapped.

7. The results could not have been more clear. Gamekeepers transformed the breeding success of curlews, lapwing, golden plover, red grouse and meadow pipit from an average of 23% of pairs fledging young to 64%.

gwct.org.uk/research/scien…

8. Three years later, areas with no predator removal saw curlew populations fell by 17% a year. Areas with predator removal saw curlew populations rise by 14% a year.
gwct.org.uk/wildlife/resea…

9. This is because curlews cannot thrive where egg predators are numerous and this now means most of lowland Britain and anywhere with many crows. Crows have become much more numerous as a result of scavenging from human activities through the winter.

10. Crow control is vital to the survival of the red-listed curlew as a breeding species not just in UK but in world. It is not an optional extra but a vital tool of conservation. Opposing it means risking the extinction of the curlew. Is that really what @ChrisGPackham wants?

9a. There is a similar pattern in Scotland with curlews thriving in the Angus glens and other areas with gamekeepers.

Curlew song for those unlucky enough not to hear it regularly: