Massimino, D., Johnston, A. and Pearce-Higgins, J.W. 2015. The geographical range of British birds expands during 15 years of warming. Bird Study 62: 523-534.
Setting the stage for describing their publication, Massimino et al. (2015) write that in response to global warming, changes in species' distributions have generally been predicted to cause "range contractions," which they note can lead to "alterations in community composition and increased extinction risk." But is this really the case?
Focusing on the first of these phenomena (warming-induced range contractions), the three UK researchers determined that over the 15-year period of their study (1994-2009) Great Britain experienced a mean temperature increase of 0.59 ± 0.27°C, which they say was equivalent to a 108 ± 2 km northward shift in isotherms. Then, working with data that had been acquired by the UK's Breeding Bird Survey program, Massimino et al. additionally determined that across all bird species studied, "poleward shifts in the leading range margin were greater than in the range-center," while "the trailing range margin was largely static, providing evidence for significant range expansion," which in their case amounted to an average north-south expansion of 15 km over 15 years.
Further in regard to this finding, Massimino et al. write that it is "in concordance with observed shifts in the distribution of terrestrial ectotherms, where thermal tolerance limits the leading range margin, but is less-directly related to the trailing margin," citing the earlier study of the subject conducted by Sunday et al. (2012). And such findings, therefore, are not supportive of an increased extinction risk.
Sunday, J.M., Bates, A.E. and Dulvy, N.K. 2012. Thermal tolerance and the global redistribution of animals. Nature Climate Change 2: 686-690.Posted 3 March 2016