Submission No 220: Arctic Warbler Phylloscopus borealis, Anna Plains Station, WA, 16 January 1996.

Verdict: Not Accepted

This submission involves a sighting by two very experienced observers from an area of flowering low dry scrub at Anna Plains Station, approximately 300km south of Broome, WA. The sighting was very brief and observations were made from a car, with the bird approaching to within 5 meters of the observers. A description and sketch was taken at the time of the sighting and the notes were then typed to form part of the submission.

The description outlines a bird considerably smaller and slimmer than nearby Rufous Songlarks with a noticeable horizontal stance. The basic colour was described as dull olive green tending greener on the head and pale grey underneath. The rump was much paler in colour contrasting with the olive back and darker tail. Tail dark grey with pale edges, possibly due to wear. Of particular importance was the very bold cream eye stripe that extended well behind the eye. Also of note was the presence of a single pale wing bar. The legs were described as flesh coloured and the bill black and fine.

The notes provided are very brief, which is understandable given the circumstances of the observation, however the committee has no hesitation in accepting that this bird was a Phylloscopus warbler. Narrowing the identification to specific status presents more of a problem. Phylloscopus warblers are notoriously difficult to identify in field particularly as they are so very active. Several Phylloscopus warblers besides P. borealis are potential candidates for Australia such as Greenish Warbler P. trochiloides and Eastern Crowned Leaf Warbler. P. coronatus Although views varied between members, the committee felt that with such a rare sighting for Australia it is necessary to eliminate all possible contenders and in particular those that have reached parts of SE Asia and Indonesia. To achieve this would involve access to a description or photographs that detail the shape and extent of crown markings, ear coverts, supercilium in front of the eye, wing bar, colour and pattern of under-body and the call. It was felt that the description provided was lacking in some of these areas therefore not allowing positive identification to specific level.

In summary the committee noted that the observers were very competent and experienced and that it is highly likely that this record does reflect a sighting of an Arctic Warbler. However the description provided does not allow the committee to rule out the possibility of other Phylloscopus warblers beyond reasonable doubt.

References and Bibliography

• Bradshaw, C. & R. Riddington. 1997. How certain are the separation features of Arctic and Greenish Warblers? British Birds 90: 180–184.
• Coates, B.J. & Bishop, K.D. 1997. A Guide to the Birds of Wallacea. Dove Publications.
• Cramp, S. (ed.) 1992. Handbook of the Birds of Europ, the Middle East, and North Africa. Vol. 6. Oxford University Press, Oxford.
• King, B. et al. 1975. A Field Guide to the Birds of South East Asia. Collins, London.
• Lewington, et al. 1991 A Field Guide to the Rare Birds of Britain and Europe. Collins, London.
• Watmough, N. 1996. Arctic or Greenish? Birdwatch August 1996: 24–30.

Tony Palliser
Chairman Birds Australia Rarities Committee (BARC)