Data from: Brain size in birds is related to traffic accidents

Estimates suggest that perhaps a quarter of a billion birds are killed by traffic annually across the world. This is surprising because birds have been shown to learn speed limits. Birds have also been shown to adapt to the direction of traffic and lane use, and this apparently results in reduced risks of fatal traffic accidents. Such behavioural differences suggest that individual birds that are not killed in traffic should have larger brains for their body size. We analysed the link between being killed by traffic and relative brain mass in 3521 birds belonging to 251 species brought to a taxidermist. Birds that were killed in traffic indeed had relatively smaller brains, while there was no similar difference for liver mass, heart mass or lung mass. These findings suggest that birds learn the behaviour of car drivers, and that they use their brains to adjust behaviour in an attempt to avoid mortality caused by rapidly and predictably moving objects.

据估算，全球范围内每年约有2.5亿只鸟类死于交通事故。这一现象颇为出人意料，因为已有研究证实鸟类能够习得限速规则。另有研究表明，鸟类可适应车流方向与车道通行规则，此举显然能降低其遭遇致命交通事故的风险。这类行为差异提示，未在交通事故中丧生的鸟类个体，其相对体型的脑容量应更大。我们针对251个物种的3521只被送至标本剥制师处的鸟类展开分析，探究其死于交通事故与相对脑质量之间的关联。结果显示，死于交通事故的鸟类相对脑质量更小，而其肝脏、心脏或肺脏的质量并未出现类似差异。上述研究结果表明，鸟类能够习得驾驶员的行为模式，并通过大脑调节自身行为，以规避由快速且可预判的移动物体所导致的死亡风险。