Higher temperatures raise the heat on upland birds
Warm summers are dramatically reducing populations of Craneflies, which is in turn is having a severe impact on the bird populations which rely on them for food, RSPB Scotland scientists have shown. This key finding spells out for the first time how climate change may affect upland species like Golden Plover. 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.
Previous research has shown how changes in the timing of Golden Plover breeding because of increasing spring temperatures might affect their ability to match the spring emergence of their Cranefly (Daddy Longlegs) 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% 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.
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. 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 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."
female Cranefly (Photo: AnnMarie Jones)
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: http://www3.interscience.wiley.com/journal/121684866/abstract.
Golden Plover productivity is strongly correlated with Cranefly abundance. As a result, fluctuations in a Golden Plover population in the Peak District from 1971-2005 were strongly linked to variation in August temperature two years earlier. Thus, a hot August results in few Craneflies emerging the following spring, and a low survival of Golden Plover chicks in that spring. This means that the plover population is more likely to decline by the next again year. Using a model that successfully tracked the observed population fluctuations, we predict increasing rates of population decline and risk of extinction by 2100 with increasing summer temperature.
The work was conducted in conjunction with staff at Aberystwyth University, Newcastle University and the University of Manchester.