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，全球每年约有2.5亿只鸟类死于交通事故。这一数据令人意外，因为已有研究表明鸟类能够习得道路限速规则。另有研究显示，鸟类还能适应车流方向与车道使用模式，这显然可降低其遭遇致命交通事故的风险。这类行为差异暗示，未死于交通事故的鸟类个体，其相对体型的脑质量应当更大。我们针对251个物种的3521只鸟类展开分析，这些鸟类均为送至标本剥制师处的样本，旨在探究其死于交通事故与否与相对脑质量之间的关联。研究证实，死于交通事故的鸟类确实拥有相对更小的脑质量，而肝脏、心脏或肺脏的质量则未出现类似差异。上述研究结果表明，鸟类能够习得机动车驾驶员的行为模式，并借助大脑调整自身行为，以规避由快速且可预判移动的物体所导致的死亡风险。