|
Case Summary for:
Submission No 254: Baird’s Sandpiper Calidris bairdii; McGraths Hill Sewerage Treatment Works, near Windsor NSW, 5 October 1998. Verdict: Not Accepted This was a difficult case, involving a small Calidris sandpiper seen by a single observer on a holding pond at McGraths Hill Sewerage Treatment Works, west of Sydney, NSW on 5 October 1998. The bird was observed for approximately 30 minutes at ranges down to 50 metres, and direct comparisons were available with two nearby Black-fronted Dotterels Elseyornis melanops. Using binoculars and a spotting scope, the observer obtained good views of the bird in clear conditions and was able to take field notes on the spot, copies of which were supplied to the Committee as part of the submission. Although other bird-watchers were informed of the bird's presence, it was not seen again despite a search over the following days. The description provided is fairly detailed, although it was considered in part to be somewhat disorganised and unclear on some important points. The bird was described as a small drab grey-brown ‘peep‘ with dark feather centres on the back (presumably the scapulars - see below), these being the only prominent markings on the upperparts. The head was described as having dark-brown streaking from the base of the bill and over the forehead and crown to the nape; and the sides of the face were streaked grey-brown. A weak (pale?) supercilium was present, as was a dark-brown loral stripe. The mantle, back, rump, uppertail coverts and tail were of a similar grey-brown colour to the rest of the upperparts, although slightly darker. The lesser, median and greater [secondary upperwing] coverts were described as grey-brown with dark-brown feather centres, which were noted as ‘shield-shaped.’ Although described as being on the [secondary] upperwing-coverts, an accompanying sketch suggests that these shield-shaped dark feather-centres were actually on the scapulars. The chin and throat were described as dull white, as were the rest of the underparts except for a ‘complete [grey-brown] breast band [with some faint fine streaking]’ which was noted as being ‘quite broad, particularly at the sides of the breast and spreading out on the sides but slightly narrower towards the centre and contrasting strongly with the belly.’ The observer felt that the breast band did not extend down the breast as much as on a Pectoral Sandpiper Calidris melanotos, and that it was considerably paler than on that species. In flight views a short (pale?) wing bar was noted (but its width was not described), and there was no sign of any white at the sides of the dark-centred rump. Particular attention was paid to the bill, which was described as ‘completely black and slender, with the slightest suggestion of a droop, the upper mandible having a slight curve and the lower looking straight.’ The tip of the bill was described as ‘noticeably fine.’ The length of the bill was estimated to be ‘longer than the distance from the rear of the eye to the base of the bill, but shorter than the width of the head.’ The bird was described as ‘smallish’, similar in height to accompanying Black-fronted Dotterels, and with legs about the same length as on that species. The wing-tips were estimated to project approximately 10 mm beyond the tip of the tail. The bird fed with a methodical picking action rather than the busy action of a stint, and was also seen to probe the mud with its bill on one occasion. Most Committee members agreed that the description is suggestive of Baird’s Sandpiper C. bairdii, primarily because the combination of size, colouration, dorsal and breast patterning, leg colour, bill length and shape, wing projection and rump pattern broadly eliminates other contenders. However, dissenting opinion noted a number of inconsistencies between the field notes and the written description, as well as a failure to sufficiently emphasise some important plumage and structural characters that are consistent for this species. As is often the situation with such records, it was felt that a lack of corroboration by other observers did not assist the claim. This case once again highlights the difficulties faced by the Committee when dealing with single observer sightings of species that are particularly rare vagrants to our area and which additionally are difficult to identify and age.
References and Bibliography:
Tony Palliser |