ABSTRACT

The diet composition and feeding preference of Myiothlypis leucoblephara (White-browed Warbler, Parulidae) were investigated in an area of the Atlantic Forest, Brazil, based on fecal samples and availability of field arthropods. Hymenoptera Formicidae and Coleoptera were the predominant taxa in the diet, corresponding to more than 70% of all items. Myiothlypis leucoblephara exhibited a preference for prey types, mainly Formicidae and Coleoptera (λ = 0.123, p = 0.01), which are the proportionally more consumed taxa when compared to other types of prey. The species also showed preference for prey sizes, with arthropods of the size classes between 2 mm-6 mm being proportionally more consumed (λ = 0.214, p = 0.001). Although it forages predominantly on the ground, M. leucoblephara also preys on arthropods regularly on the foliage, which allows expanding the range of substrates exploited as well as obtaining different types of prey, probably favoring the differential consumption. On the other hand, the preference for intermediate size prey suggests foraging optimization, consuming feeding items with high energy-intake rate in relation to costs of predation. Whether the preference results from active selection by the birds or simply by the difficulty of finding less abundant items needs to be investigated.

摘要

饮食和组合物的摄食偏好Myiothlypis leucoblephara（白眉莺，Parulidae）在大西洋森林，巴西的区域进行了研究，基于粪便样品和场节肢动物可用性。膜翅目蚁科和鞘翅目是饮食中的主要分类群，占所有项目的 70% 以上。Myiothlypis leucoblephara表现出对猎物类型的偏好，主要是蚁科和鞘翅目（λ = 0.123，p = 0.01），与其他类型的猎物相比，它们是按比例消耗更多的分类群。该物种还表现出对猎物大小的偏好，2 毫米-6 毫米大小的节肢动物按比例被消耗更多（λ = 0.214，p = 0.001）。虽然它主要在地面上觅食，M. leucoblephara还定期捕食叶子上的节肢动物，这允许扩大利用底物的范围以及获得不同类型的猎物，可能有利于差异化消费。另一方面，对中等大小猎物的偏好表明觅食优化，消耗与捕食成本相关的能量摄入率高的饲料。偏好是由鸟类主动选择引起的，还是仅仅由于难以找到数量较少的物品，需要进行调查。