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Case Summary for:
Submission No 246: Newell’s Shearwater Puffinus (auricularis) newelli; Phillip Island, Norfolk Group, 2 December 1997. Submitted by: Mike Carter. Verdict: Accepted This case concerns a black-and-white shearwater found ashore at night on Phillip Island in the Norfolk Group, sitting alongside a Kermadec Petrel Pterodroma neglecta. Not knowing the identity, the bird was photographed prior to release but no other data was collected. The prints were forwarded to Mike Imber in New Zealand for identification. Subsequently, a copy of the photographs together with an estimate of the birds wing and bill measurements were sent to Mike Carter who then forwarded them on to BARC for review. Important characters revealed in the photographs include; overall black-and-white plumage, a sharply demarcated head pattern, an obvious post ‘auricular’ patch, completely white axillaries and clear black leading edges to the underwing. By comparison with the hands holding the bird, measurements estimated by Mike Imber from the photographs are 240mm for the wing-length and 38mm for the bill length. The photographs which were taken at night using artificial light may be under-exposed causing concern regarding reliability of tonal rendition (black verses brown). They clearly show the underwing, head pattern and to some degree the underside and bare parts of the bird. Unfortunately the under-tail and the under-tail coverts cannot be seen and are not described. These features are important in distinguishing several similarly plumaged species that occur in the Pacific and the absence of this data resulted in a particularly difficult case involving a second round of voting. It was agreed by committee members that Fluttering Shearwater P. gavia, Hutton’s Shearwater P. huttoni and Little Shearwater P. assimilis can be eliminated by (1) the large size, (2) the presence of a post auricular patch, (3) bill length & proportion and (4) pattern of the underwing. Some of the slightly larger shearwaters were more difficult to eliminate; notably Manx Shearwater P. puffinus, Townsend’s Shearwater P. (auricularis) auricularis, Audubon’s Shearwater P. lherminieri and Black-vented Shearwater P. opisthomelas. Consequently we approached Don Roberson a well known ornithologist in the United States with considerable experience with Newell’s and related species. He concluded that this bird was indeed a Newell’s Shearwater thus endorsing the opinion of most committee members. Roberson commented that "this bird looked essentially identical to several photographs from Hawaii of grounded (Newell’s Shearwater) birds photographed at night. It shows the classic ‘wedge’ indentation behind the auriculars, a strongly demarcated black-and-white facial pattern and typical foot colour. Townsend’s is very similar. However, the facial pattern is distinct. The facial patterns of Townsend’s, Manx and Black-vented Shearwaters shows a wide range of variation. but none match the absolute standard Newell’s Shearwater images that are depicted in the photographs provided. Townsend’s Shearwater is also browner overall". Of passing concern to some was the little known Pacific populations of Audubon’s Shearwater P.l.dichrous and P.l.gunax. We know from observations of Audubon’s seen off Sydney February 1984 (Carter, Eades and Palliser pers.obs.) and again in February 1987 (Carter 1988) that this species can show a slight post-auricular notch or at least a hint of one. It is also known that P.l.dichrous can lack this marking (photo in Jenkins 1973). The difference seems to be that these Audubon’s taxa show at best a slight indentation rather than a short but distinct wedge as in Newell’s Shearwater. The larger bill proportions of the bird photographed also indicate Newell’s rather than Audubon’s Shearwater. In summary, committee members voted (7/1 in favour) for acceptance basing their views on a combination of size, bill shape and proportions, the very black-and-white appearance, the sharply demarcated head pattern, shape and extent of the post auricular patch, the underwing pattern and the bicoloured pink-and-black legs and feet. Newell’s Shearwater is a rare, perhaps endangered, species which breeds in the Hawaiian Islands and winters in the tropical Pacific. There is one beach-cast specimen from the North Island of New Zealand (M. Imber pers. comm.). Townsend’s Shearwater breeds on Revillagigedo Islands off Western Mexico and disperses seawards up to 500 miles in all directions, so is very unlikely to occur this far west. Manx Shearwater has occurred as a vagrant in both Australia and New Zealand. This represents the first confirmed record of Newell’s Shearwater for Australia.
References and Bibliography
Tony Palliser |