The white-bellied sea-eagle (Haliaeetus leucogaster) and eastern osprey (Pandion haliaetus) are highly territorial raptor species associated with coastal regions and inland waterways. These top order (apex) predators are recognised as environmental indicators and their presence is synonymous with unspoilt natural systems. In South Australia both species have small fragmented populations which are declining, this has led to both species being listed as endangered under the South Australian National Parks and Wildlife Act 1972. State-wide, White-bellied sea-eagles number 70 to 80 pairs and ospreys 55 to 65 pairs, with the majority found occupying more remote offshore island habitats, such as those found on KI.
The Coast and Marine program has been involved in monitoring these coastal raptors on KI since 2005. A population census of known territories is undertaken every five years with the last occurring in 2015. A total of 18 occupied white-bellied sea-eagle and seven osprey territories were identified on the island, which represents approximately 30 per cent and 20 per cent of South Australia's total population, respectively.
Why are coastal raptors under threat?
Like many other coastal birds there is significant overlap in habitats preferred by white-bellied sea-eagles and ospreys and human activity. The principal known threats to these coastal raptor species is disturbance during critical breeding periods and inappropriate coastal development too close to breeding territories. The breeding success of coastal raptors is also impacted through predation on chicks and the contamination of coastal food-chains. These threats can interact with the breeding success of coastal raptors in a way that produces a chain reaction where one impact triggers a response that increases exposure to another.
How can you help coastal raptors?
We can all help to minimise our impact on coastal raptor populations on KI. Coastal raptors are particularly sensitive to disturbance during critical breeding periods so it is important to avoid locations which support these top order predators as much as possible. The critical breeding periods for white-bellied sea-eagles are between May and November and August to February for ospreys. If you observe coastal raptors becoming agitated by your presence, move away immediately. If you would like more information or would like to report an activity which you believe is threatening coastal raptors please contact Natural Resources Kangaroo Island on 8553 4444, or email firstname.lastname@example.org.