A study of nesting sparrowhawks Accipiter nisus using video analysis

Abstract

Capsule: Chick age influenced female prey size and the provisioning rate of each parent while rainfall increased female brooding in a single sparrowhawk territory in Edinburgh. Aims: To study the details of prey delivery, female brooding and the factors affecting chick mortality in a single sparrowhawk territory in Edinburgh. Methods: Video footage collected from a sparrowhawk nest in the Royal Botanic Garden Edinburgh in 2011 and 2012 was used to record the occurrence and size of prey deliveries by each parent and the time spent brooding by the female, with respect to the age of the chicks and daily rainfall measurements. The results were compared to observations made at three nests in Ae Forest (southwest Scotland) by Newton [1978. Feeding and development of sparrowhawk Accipiter nisus nestlings. J. Zool. 184: 465–487]. Results: Once the chicks were four days old, the total number of prey deliveries per day did not change with age. However, there was a corresponding decrease and increase in provisioning rates by male and female parents, respectively, although the male contribution remained highest throughout. In the late stage of the nestling period, the higher food requirement of the chicks was matched by an increase in female prey size. The total rainfall per day had no effect on the rate of prey deliveries by either sex but did cause a rise in the time spent brooding by the females each day. A higher frequency of smaller prey deliveries and more extensive female brooding and prey partitioning occurred at both nests compared to those studied by Newton [1978. Feeding and development of sparrowhawk Accipiter nisus nestlings. J. Zool. 184: 465–487]. Conclusion: The study nests were probably in a particularly high quality sparrowhawk territory and wetter weather may have been the primary reason for the reduced reproductive success in 2012.