Improving monitoring methods and determining the breeding success of Grey Crowned Cranes (Balearica regulorum) within a key agricultural area in South Africa

Abstract

Endangered Grey Crowned Cranes (Balearica regulorum) primarily inhabit unprotected areas subject to substantial land-use transformation. With a limited understanding of this species’ reproductive success, this study aimed to i) improve monitoring methods of nesting and social groupings and ii) identify this species’ reproductive output in response to environmental conditions. To produce monitoring guidelines, I compared behavioural responses of pairs, families and flocks to traditional on-foot and drone monitoring. Flocks took flight at greater distances when approached on-foot than by drones, while nesting birds were more sensitive to vertical drone approach angles. Breeding metrics from 95 nest sites revealed a low overall breeding success, with most nest sites failing to transition from eggs to hatchlings. Higher success rates were found at nests closer to natural grasslands and human development. Altogether, this crane species would benefit from consistent monitoring, collaborative efforts, and a skilful balance between preserving biodiversity within rapidly developing landscapes.