Notes on two unusual Circus harriers in Perth, Western Australia, and implications for identification of Swamp and Eastern Marsh Harriers in Australasia

Abstract

A long-staying Circus harrier with features atypical for the locally common Swamp Harrier C. approximans was present between 2014 and 2023 at Herdsman Lake, Western Australia. These plumage features are not recorded in any reference literature for the Swamp Harrier, thus leading to speculation as to the identification of this bird. Several under- and upperwing features more consistent with Eastern Marsh Harrier C. spilonotus are noted; however, other plumage features are more typical of Swamp Harrier, a species with highly variable plumage. This paper documents the atypical features of this and a similar individual from the Eric Singleton Bird Sanctuary, Western Australia, and briefly discusses related identification issues.