Modelling climate change impacts on the distribution of breeding birds in Britain and Ireland

Predictions of the availability of suitable climate space for the breeding distributions of eight birds of conservation importance were modelled for the current climate and four climate change scenarios using the SPECIESv2 neural network model. Changes were quantified in relation to six bioclimatic variables and the model was trained on a combination of observed data derived from the European and Britain/Ireland atlases of breeding bird distribution. The present distributions were satisfactorily simulated both at the European and Britain/Ireland scales with Kappa coefficients of agreement greater than 0.7. The predicted responses to climate change demonstrate that the distribution of many breeding birds in Britain and Ireland may be affected by climate change, but that the effects are likely to differ between species. Short-term and less severe changes in climate had a positive effect on the potential climate space of five species (Streptopelia turtur, Motacilla flava, Luscinia megarhynchos, Acrocephalus scirpaceus and Sitta europaea) and a negative affect on one species (Tetrao urogallus), whereas the overall suitability of Parus montanus and Gavia stellata remained relatively stable. More severe long-term changes in climate were predicted to lead to a contraction in the potential area of suitability of Luscinia megarhynchos and Sitta europaea in south east England, and a large reduction in the area of Parus montanus in southern England. Based on the total change in potential climate space in Britain and Ireland, the species most sensitive to climate change were Tetrao urogallus (negatively affected) and Acrocephalus scirpaceus (positively affected). Although the models provide a useful indication of potential changes in bird distributions, the extent to which bird populations will track changes in climate space will depend on many different factors including their ability to disperse, their habitat and food requirements (and how these are influenced by climate change) and their population status and dynamics.