The project's latest paper to appear, in Biology Letters, reports that cliff swallows that die during severe weather and that live in larger colonies have smaller brains than birds that succumb due to other causes. This study was made possible by our specimen collection that consists of about 2500 birds that we found dead over the last 38 years, these birds having died during bad weather, hit by cars, or for other reasons. Gigi Wagnon did this analysis as part of her Masters thesis. The results seem to suggest that cliff swallows faced with more unpredictable and challenging environments, such as when food is scarce during bad weather or in small colonies where one cannot rely on other colony members to find food or avoid predators, have an advantage if they have the greater cognitive skills inherent in having larger brains. More frequent spells of bad weather, as predicted under climate change, may select for bigger brains, on average, going forward.
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