OOS 29-5
Using citizen science to examine avian responses to environmental change in the UK
As urban land cover expands, private gardens and backyards are expected to play an increasingly important role in conserving avian biodiversity. But establishing links between garden resource availability and bird distribution patterns requires on-going large-scale survey effort, only possible with the input of citizen scientists. Garden BirdWatch (GBW) is one of many monitoring programs conducted by the British Trust for Ornithology (BTO). Established in 1995, it is the largest year-round survey of garden birds in the world, with more than 14,000 citizen scientists throughout Britain and Ireland submitting systematic observations of birds seen in gardens each week. These data have proven especially valuable for examining drivers of avian spatio-temporal patterns, including migratory changes in Eurasian Blackcaps (Sylvia atricapilla).
Blackcaps from central Europe have been wintering in Britain with increasing frequency over the past 50 years, rather than migrating south to the Mediterranean. There is now an established wintering population in Britain, and fitness benefits attributed to this novel migration strategy have been reported on the breeding grounds. Using over 2 million weekly records of Blackcap presence/absence during winter months we test the possible mechanisms driving the microevolution of Blackcap migration behavior; namely local habitat, winter climate and supplementary feeding activities.
Results/Conclusions
Results submitted from 12,113 gardens between 1999 and 2011 show that Blackcap wintering patterns vary significantly among 12 regions of the UK. Blackcaps are observed in 58.4% of gardens in the South West during winter compared to only 10.0% in the East of England on average, and we show that this latitudinal difference can be explained by variation in winter climatic conditions. Furthermore, Blackcap observation rate in gardens during winter is significantly positively correlated with the amount of surrounding suburban land cover and the provision of wild bird foods. Our results provide the first empirical support for previously proposed hypotheses that increased feeding opportunities, in the form of artificial food, and more favorable climatic conditions have facilitated the establishment of a wintering population of Blackcaps in Britain. It is evident from these findings that citizen science can provide an effective tool for investigating avian responses to environmental change.