Editor´s Choice: Avian body size change in response to environmental change

Submitted by Johan on 18 November 2014.

That avian populations respond to climate change by changes in phenology and distribution is well known but should we predict any consistent trends in body size?

In a very interesting paper published in Journal of Avian Biology Gardner et al. set out to answer this question by examining annual variation in body size of 24 Australian passerine species, encompassing almost 50 years, using museum specimens. They found that 67 % of the species showed a consistent linear variation in body size during the years 1960-2007. Thus, broad-scale directional changes in for example the climate during this period have potentially a large effect on body size. Body size in response to a warmer climate has been predicted to decrease due to Bergmann’s rule or changes in primary productivity. The majority of the species with a consistent body size trend also showed a decrease but most interestingly some (5 out of the 24 species) actually responded by a directional increase in body size. Thus, the body size response to climate change is complex and may for certain species be more affected by a changed incidence of extreme temperatures or by precipitation than just by the average increase of mean temperature.

Jan-Åke Nilsson, Editor in Chief

As with all our Editor´s Choice papers this one can be accessed for free for a limited time:

http://onlinelibrary.wiley.com/doi/10.1111/jav.00431/full

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