Responses of White-bellied Sea-Eagles 'Haliaetus leucogaster' to encroaching human activities at nest sites

Abstract

Nest sites of the White-bellied Sea-Eagle 'Haliaeetus leucogaster' are under increasing pressure from encroaching development and other human activities in coastal south-eastern Australia. Nests in the path of development have sometimes been destroyed or displaced, or become too disturbed for continued successful breeding. This paper reviews eight such cases, six for which mitigation measures (artificial platform, exclusion or environmental protection zones, forced rebuilding at safer sites) were attempted, successfully in three of these (i.e. young fl edged) after management actions: (1) Relocation of the intact nest to a platform among other trees nearby (successful in the short term (6 years), ultimately abandoned); (2) Removal of a pair's nests in a highway upgrade zone, to encourage rebuilding in safer forest sites nearby (initially successful); (3) Exclusion zone (50 m and 130 m radius) buffering a long-term nest from a new housing estate on three sides (successful in the short term, 2 years); (4) E3 zoning ('Environmental Management') of a bushland remnant enclosing a formerly productive eagles' nest adjoining a new housing estate (nest unsuccessful then abandoned after development proceeded); (5) Site management of a long-term nest in a recreation reserve 30 metres from a new housing estate (inconclusive, as the eagles left the site before clearing commenced); (6) Deactivation of an established nest in a pipeline easement, to encourage rebuilding in safer forest sites nearby (use and outcome of a possible alternative nest not determined by the proponent). Overall, buffer zones (50-130 m around active nests) had mixed success, and the more highly and frequently disturbed nests had low breeding productivity or were abandoned. With rapid expansion of urbanisation likely to continue in coastal northern New South Wales, this region may become a population sink for the White-bellied Sea-Eagle. Therefore, given its small population (~800 pairs in NSW) and the potential for an estimated 10 percent decline in abundance in three generations (this study), it is recommended that the Sea-Eagle be considered for listing as vulnerable in NSW.