Since foot preference of cockatoos and parrots to hold and manipulate food and other objects has been associated with better ability to perform certain tasks, we predicted that either strength or direction of foot preference would correlate with brain size. Our study of 25 psittacine species of Australia found that species with larger absolute brain mass have stronger foot preferences and that percent left-footedness is correlated positively with brain mass. In a sub-sample of 11 species, we found an association between foot preference and size of the nidopallial region of the telencephalon, an area equivalent to the mammalian cortex and including regions with executive function and other higher-level functions. Our analysis showed that percent left-foot use correlates positively and significantly with size of the nidopallium relative to the whole brain, but not with the relative size of the optic tecta. Psittacine species with stronger left-foot preferences have larger brains, with the nidopallium making up a greater proportion of those brains. Our results are the first to show an association between brain size and asymmetrical limb use by parrots and cockatoos. Our results support the hypothesis that limb preference enhances brain capacity and higher (nidopallial) functioning.

中文翻译：

---

与澳大利亚鹦鹉的脚部偏好相关的大脑大小

由于凤头鹦鹉和鹦鹉保持和操纵食物及其他物体的脚部偏好与执行某些任务的更好能力相关联，因此我们预测，脚部偏好的强度或方向将与大脑大小相关。我们对澳大利亚的25种psittacine物种的研究发现，具有绝对绝对大脑质量的物种具有更强的脚部偏爱，并且左脚率与大脑质量呈正相关。在一个11种物种的子样本中，我们发现脚的偏爱与端脑的肾盂区域的大小之间存在关联，该区域相当于哺乳动物的皮质，并且包括具有执行功能和其他更高级别功能的区域。我们的分析表明，相对于整个大脑，左脚使用百分率与尼多帕皮的大小呈正相关，而与视轴的相对大小则不相关。具有更强左脚偏爱的Pttattacine物种的大脑更大，而尼多帕金森氏菌在这些大脑中所占的比例更大。我们的研究结果首次显示了大脑大小与鹦鹉和美冠鹦鹉使用不对称肢体之间的关联。我们的研究结果支持这样的假说，即肢体偏爱可以增强大脑能力并增强（肾盂）功能。我们的结果首次显示出大脑大小与鹦鹉和美冠鹦鹉使用不对称肢体之间的关联。我们的结果支持这样的假说，即肢体偏爱可以增强大脑容量和更高的（肾盂）功能。我们的结果首次显示出大脑大小与鹦鹉和美冠鹦鹉使用不对称肢体之间的关联。我们的研究结果支持这样的假说，即肢体偏爱可以增强大脑能力并增强（肾盂）功能。