Finding food in a human-dominated environment: Exploring the foraging behaviour of urban Torresian Crows Corvus orru

Abstract

Urbanisation provides both challenges and opportunities for wildlife living within these novel environments. Corvids (crows and ravens), although naturally wary and neophobic, have become among the most abundant urban bird groups throughout the world. Although such success has been attributed to their exploitation of human-derived food wastes, the foraging behaviour of urban corvids is poorly understood. We investigated foraging among Torresian Crows Corvus orru in suburban Brisbane, Queensland, by observing their behaviour at 15 parks and commercial sites in 2014-2015. The items consumed by foraging crows were identified specifically and with regard to origin during 5-minute focal observations. In addition, the reactions of birds to the presence of humans were noted. We found that the diet of the species was dominated by natural foods, especially insects, although around a third of items were of human origin. Crows selected a very wide range of food types and were more likely to consume natural foods during the morning but anthropogenic foods during the middle of the day. Crows were prone to flying away from a foraging site if people were close by. This study demonstrated that urban Torresian Crows rely primarily on natural foods, probably switching to scavenging only when nutritional needs have been met.