Similar parental care in Milvago chimango: the importance of the environment and chick age

Parental care in raptors is particularly important since it can have strong implications for their ecology and reproductive success. Chimango caracara (Milvago chimango) is the most abundant and common raptor in Argentina, as it nests in a wide variety of environments, including urbanized areas. However, there are no studies describing parental care behavior of this raptor. We performed focal observations (109 h) in 24 nests of chimango in two environments (suburban and rural) of La Pampa province, during the 2016/2017 breeding season. Incubation time did not differ significantly between males and females, and it did not depend on lay size. Similarly, feeding rate (number of prey contributions per hour) was not affected by sex or by the number of chicks in nest. However, feeding rate increased significantly with the age of the chicks (presumably, in order to meet higher energetic requirements), and it was lower in the suburban environment than in the rural one. None of these variables (incubation time and feeding rate) explained the variation in the reproductive parameters of chimangos (reproductive success and productivity), a fact that evokes the importance of other external factors for the success of nests. These findings suggest a similar (and symmetrical) parental investment of both sexes in the reproductive stage. Concerning the degree of anthropic disturbance in the environment, it could be affecting the parental care behavior of those raptors that nest in urbanized areas.