Daddy long leg shortage to affect upland birds

26/03/2009 08:29:58 Higher temperatures raise the heat on upland birds
March 2009. Warm summers are dramatically reducing populations of daddy long legs, which, in turn, is having a severe impact on the bird populations which rely on them for food, RSPB Scotland scientists have shown.

Golden Plover - Summer Plumage on moorland. Breeding is much less successful when there is a lack of craneflies. Photo credit Chris Gomersall (rspb-images.com).

Golden plover under threat
This key finding spells out for the first time how climate change may affect upland species like golden plover, a colourful thrush-sized wading bird. There are fears that this bird may be pushed towards local extinction by the end of the century. But the paper also points a way forward to how we can attempt to strengthen habitats to help wildlife adapt to our changing climate and prevent such consequences.

95% reduction in spring craneflies
Previous research has shown how changes in the timing of golden plover breeding due to increasing spring temperatures might affect their ability to match the spring emergence of their cranefly (daddy long legs) prey. The new research shows that much more severe are the effects of increasing late summer temperatures which kill cranefly larvae in peatland soils as the surface dries out, resulting in a drop of up to 95 per cent in numbers of adult craneflies emerging the following spring. With these craneflies providing a crucial food source for a wide range of upland birds like golden plover, this means starvation and death for many chicks.

1.9ºC warmer than 35 years ago
As a result of average temperature increasing by 1.9ºC in late summer in the Peak District study area over the last 35 years, this has become the most important climatic factor affecting the local golden plover population. If these trends continue, as predicted by current climate models, we would expect many plover populations, particularly in the south of their range where temperatures will be highest, to be increasingly likely to decline, or even face extinction.

Lead Author Dr James Pearce Higgins of RSPB Scotland said: "Many studies predict dire effects of climate change upon wildlife but this study provides a rare example of where such predictions are based on a detailed understanding of a species' requirements, linking the effects of climate on food resources to changes in breeding success and population size.

Solutions
"This is the most worrying development that I have found in my scientific career to date. However, by understanding these processes, we now have the chance to respond. If we can maintain good quality habitats for craneflies then we can help the birds too. For example, by blocking drainage ditches on our RSPB Forsinard reserve in the North of Scotland we hope to raise water levels and reduce the likelihood of the cranefly larvae drying out in hot summers. The fight against climate change will increasingly mean strengthening habitats to protect vulnerable species, as well as trying to reduce emissions."

The new paper, Impacts of climate on prey abundance account for fluctuations in a population of a northern wader at the southern edge of its range, is published in the scientific journal Global Change Biology and is available here.