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Case Summary for:
Submission No 226: Glossy Swiftlet Collocalia esculenta; Broome, WA, 12 March 1996. Submitted by: C. J. Hassell et.al. Verdict: Accepted This observation concerns the sighting of a swiftlet from the port of Broome, WA. 12 March 1996 following cyclone ‘Kirsty’ which passed 130 km from shore 36 hours earlier. Good views were obtained by eight observers for several minutes as the bird flew to within 6-7 metres. The description and sketch provided to the committee details a bird with a fluttering stiff winged flight with entirely dark upperparts and a slightly notched tail. There was no hint of a pale rump. Underparts were described as "dirty white" palest on the belly, fading into the darker colour on the flanks and breast. Size was estimated to be much smaller than Fork-tailed Swift and perhaps similar to that of a Tree Martin Hirundo nigricans although less robust in the body. The overall impression being that this bird was dull grey-black in colour without any gloss or sheen to the plumage. Although, as the observer points out conditions were overcast at the time meaning that it may not have been possible to view any gloss in the plumage. Although the description and field notes provided were very brief the committee voted to concur with the observers and accept that this record as a Glossy Swiftlet. The fluttering buoyant flight is typical for the species and the combination of dark upperparts, pale belly and slightly notched-unforked tail leaves little doubt. Recent taxonomy (e.g. Sibley & Munroe 1990) splits Collocalia esculenta into separate species C. esculenta and C. linchi. Australian taxonomy has yet to follow this, pending further work on the issue (Christidis & Boles 1994). It has generally been assumed that C. e. natalis from Christmas Island forms part of the esculenta group, Somadikarta (1986) and Carter (1994) though, have raised doubts about this. There being a possibility that natalis belongs to the linchi group. Separation between the two in the field is poorly known and is said to rely primarily on the glossy tone of the upperparts, linchi having upperparts with a duller oil-green gloss (Coates et. al 1997). Unfortunately this record is not detailed enough to warrant separation to this level, consequently should this species be split in the future then this record may become insupportable. Although other reports exist this is only the third record to be reviewed and accepted by the committee.
References and Bibliography
Tony Palliser |