Do Birds with Larger Brains Collide with Vehicles Less Often?
At least 95% of species that ever existed have become extinct under natural conditions. Hence, the pathway to extinction is well traveled. Of concern today is whether humans have accelerated the extinction rate. Of the anthropogenic sources of mortality, vehicular collision provides another source of unnatural (or additive) avian mortality. Whether birds possess behavioral innovations to collision avoidance was addressed by Møller and Erritzøe (2017). They suggested that birds hit by moving vehicles had relatively smaller brains than those that died from other causes, which were not specified but likely include depredation by feral cats and collisions with structures. We explored their published data and confirmed the basic result. However, we found that the effect is subtle, and no species showed an absolute difference in relative brain size between individuals hit or non-hit, and in some species, individuals hit by vehicles had larger brains. We consider their interesting conclusion open to further testing with a more precise measure of brain size.
The difference in relative brain size between birds Hit or Not Hit by vehicles is subtle.
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