|
Case Summary for:
Submission No 233: American Golden Plover Pluvialis dominica, Pitt-Town Lagoon, Sydney, NSW. 22 November 1997. Verdict: Not Accepted This case concerns the observation of two Pluvialis plover feeding and preening on the edge of a freshwater lagoon on 22 November 1997 at Pittown, Sydney, NSW. Detailed notes were taken in the field and these were analysed and enhanced to form the basis of the submission. In summary, particular attention was made of important features including the extent of the primary projection, length & colour of the tertials, overall colouration, facial markings and structure. Although observed by several ornithologists only one managed to see the birds well enough to obtain field notes. Some of the more convincing aspects of the field notes include: (1) The complete lack of buff, except for one bird showing a hint of buff in front of the eye; (2) Size almost identical to typical P. fulva; (3) Primary projection estimated to be at least 30mm beyond the tip of the longest tertial; (4) Primary projection beyond the tail tip estimated to be just shorter than the bill length 20mm; (5) Tip of longest tertial falling well short of the tail; (6) The distance between primary tips estimated to be 8mm, although the distance between primaries 9 & 10 was approximately 3-4mm; (7) One bird that was studied well had four primary tips visible beyond the longest tertial; (8) Very attenuated rear end; (9) Feet did not project beyond the tail in flight. As with other cases relating to this species the committee once again pointed out how very difficult it can be to separate American Golden Plover P. dominica from Pacific Golden Plover P. fulva in the field and this problem has been well illustrated overseas. Further complications exist in this part of the world as it has been suggested by measurement that Victorian P. fulva are longer winged than what is stated for Siberian breeding birds and subsequently the measurements fall mid-way between Siberian P. fulva and the P. dominica (Barter 1988). The existence of a group of birds which are intermediate in wing length casts doubt on anyone’s ability to reliably separate the two species (although more research is needed in this area). Having said this, much of the material provided is suggestive, particularly the descriptive portions detailing the attenuated rear of the bird. However, several members consider that the primary projection beyond the longest tertial should be considerably longer than 30mm in most P. dominica. Committee members noted that there was (understandably) some ambiguity in the field notes, due to the fact that more than one bird was present. This combined with a lack of confirmation in the form of a photograph, detailed sketches, corroboration from additional observers or comparison with birds known to be P. fulva has prompted most members to vote against acceptance. As anticipated this has proven to be a particularly difficult case, once again illustrating the very high level of detail required for this most difficult species. It was generally agreed that the birds may have been in juvenile plumage and that this account may well refer to sightings of P. dominica. To date there is only one confirmed record of this species for Australia, that being a worn and faded juvenile seen and photographed at Byron Bay, NSW on 8 November 1994 (BARC case no. 189). Detailed field notes and photographs were invaluable in confirming the identification of that individual.
References and Bibliography
Tony Palliser |