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Case Summary for:
Submission No 260: Brown Shrike Lanius cristatus; Christmas Island, 20 - 22nd November 1998. Submitted by Allan Richards & Reg Clark. Verdict: Accepted This submission involves a bird that was immediately identified as a shrike as it perched on overhead electricity wires near the Christmas Island phosphate mining depot. The bird was observed for approximately 15 minutes on the 20th November under ideal conditions and was relocated again on the 22nd November 1998. The description is brief but does clearly depict a shrike. The bird being described by both observers as having a brown cap, back & rump and slightly darker brown tail and wings. Most apparent was a distinct black eye-stripe combined with a faint pale eye-brow. One observer noted an unbarred back and the presence of some scalloping on the sides and yet the second observer commented that the back had a distinct scaly pattern which was quite distinctive. From below the bird was off-white shading to a fawn colour towards the sides. Size was estimated to be similar to that of a Common Starling Sturnus vulgaris. Essentially, members agreed that collectively the record does ring true for an immature (first basic) Brown Shrike as claimed and certainly the descriptions and illustrations in Lefranc & Worfolk (1997), Lekagul & Round (1991), Brown Shrike in Cramp (1993) and Beaman & Madge (1998) support this. The only ID contenders are Brown Shrike Lanius cristatus subspp. and Tiger Shrike L. tigrinus, both good chances for vagrancy to Christmas I. or even to nw. Australia by virtue of their status as long-distance migrants that over-winter in S.E. Asia as far south as the Greater and Lesser Sundas. The combination of brown upperparts with dark scalloping on the nape and ‘back’; off-white under-body with a fawn wash and dark scalloping on the flanks; a black face-mask coupled with a dull creamy supercilium; and a pale, dark-tipped bill appears to be diagnostic of a first immature Brown Shrike of one of the brown-capped subspecies cristatus, confusus or superciliosus; the far eastern subspecies lucionensis can be ruled out by its ashy-grey cap and brownish-grey mantle, back and scapulars. Tiger Shrike is easily ruled out by its combination of grey cap with black face-mask, and white under-body with (in female only) bold black flank-barring and no buff wash on flanks (cf. buff flank-wash overlaid by more scallop-shaped barring on imm. Brown Shrike). Identification to subspecies is possible on the basis of the precise colour tone of the brown upperparts. Alas, all we have to go on is the comment that the upperparts were ‘brown’ or ‘khaki brown’. The latter colour sounds closest to cristatus or confusus, which have very similar russet-brown upperparts, but not for supercilious which has a distinctly richer red-brown or rufous-brown dorsum than the other two forms. According to Lefranc & Worfolk, cristatus does not over-winter as far south as Sumatra and Java or in the Lesser Sundas whereas the other two forms do. In all probability then it was either a confusus or a supercilious. The committee finally resolving to accept this record as Australia’s first Brown Shrike in first immature plumage, subspecies undetermined.
References and Bibliography
Tony Palliser |