Dark-Sided Flycatcher Muscicapa Sibirica in the Cocos (Keeling) Islands

1 AUSTRALIAN FIELD ORNITHOLOGY 2011, 28, 1–12 Dark-sided Flycatcher Muscicapa sibirica in the Cocos (Keeling) Islands NEVILLE B. PAMMENT and MARJORIE E. PEGLER P.O. Box 336, Daylesford, Victoria 3460 (Email: [email protected]) Summary A Dark-sided Flycatcher Muscicapa sibirica was observed and photographed on Home Island, Cocos (Keeling) Islands, on 6–7 November 2008. Its identification was based on its compact shape, its very dark, diffusely streaked breast and flanks, its wing-length and primary projection, its short bill with concave sides, prominent white half-collar, asymmetrical eye- ring and other features. The field marks which distinguish this species from similar-looking Muscicapa flycatchers are discussed. This is the first record of this species for the Cocos (Keeling) Islands and the second (and first photographic) record for Australian territory (Birds Australia Rarities Committee Case no. 593). Introduction Home Island (12°07′S, 96°54′E, area 0.95 km2) is part of the Australian External Territory of Cocos (Keeling) Islands and the home of the Cocos Malay population. Apart from housing and domestic gardens, the island is largely covered with introduced Coconut Palms Cocos nucifera, the native vegetation having been almost entirely removed in the nineteenth century (Bunce 1988). A striking feature of all of the islands of the Cocos (Keeling) Group is the near-complete absence of passerines, the only current breeding species being the introduced Christmas Island White-eye Zosterops natalis, which occurs only on Horsburgh Island and the remote North Keeling Island. Other than the Barn Swallow Hirundo rustica, which is a regular non-breeding visitor (Higgins et al. 2006), passerines sighted on the remaining islands are uncommon to very rare vagrants. On 6 November 2008 NBP found a small flycatcher with a prominent white half-collar and heavily streaked underparts sallying for insects from a row of Sea Almond Terminalia catappa trees, on the south-western (lagoon) side of Home Island. The location is just outside the walled garden of Oceania House, the former residence of the Clunies-Ross family. NBP and MEP observed the bird again over several brief intervals on the morning of 7 November and obtained photographs with a compact camera. Based on limited experience in Europe with the Spotted Flycatcher Muscicapa striata, the only member of this genus that we had previously seen, we suspected it to be one of the grey-brown muscicapid flycatchers wintering in south-eastern Asia. After consulting Robson (2005), we identified it as a Dark- sided Flycatcher M. sibirica (also known as Sooty or Siberian Flycatcher). The sighting has been accepted unanimously by the Birds Australia Rarities Committee (BARC) (Case no. 593, T. Palliser in litt. 26 March 2010). Efforts to relocate the bird by NBP on 15–16 November and by others on 3–4 December 2008 (R. Baxter pers. comm.) were unsuccessful. This is the first record of the species for the Cocos (Keeling) Islands and the second (and first photographic) record for Australian territory. The only other accepted record in Australian territory is of a bird seen by John Darnell at the sewerage ponds at Shay Gap (~20°31′S, 120°08′E), north-western Western Australia, on 15 October 1983 and thought to be of the subspecies sibirica AUSTRALIAN 2 PAMMENT & PEGLER FIELD ORNITHOLOGY [Johnstone & Storr 2004; Higgins et al. 2006; BARC Case no. 588 (Palliser in litt. 21 March 2010)]. This report describes the Home Island sighting, including the features used to distinguish the bird from similar muscicapid flycatchers. Behaviour and description Behaviour On both days, the bird frequented a row of partially defoliate Sea Almond trees, sallying out infrequently to catch flying insects and returning to either the same perch or a nearby one in the same or an adjacent tree. It typically perched in the lower or middle canopy ~3–4 m above the ground, usually in a sheltered position, but occasionally on a lower, exposed branch. Short bursts of activity for several minutes were followed by longer periods in which it remained perched and was difficult to relocate. It was not heard to call. Size, structure and bare parts The bird was about the size of a Petroica robin, with an upright stance and a compact, slightly plump appearance. The bill was thin and short, its length from the tip to the base of the forehead being about half of the distance between the anterior edge of the eye and the point where the upper mandible met the forehead (Plate 2). Viewed laterally, the bill was shallow along most of its length, thickening slightly towards the base. The sides of both mandibles were uniformly grey. Viewed from below, the width of the base of the bill was only slightly shorter than the bill’s length, appearing as a broad isosceles (almost equilateral) triangle. The tip of the bill was narrow and pointed, and its sides slightly concave (Plate 3). The bill’s ventral surface was dark except for a dark-edged pale triangle at the base. The irides were dark, and the toes and feet grey. The projection of the longest primary beyond the tip of the longest tertial was slightly longer than the projection of the longest tertial beyond the longest greater covert (relative primary projection was measured as ~105% from a photograph). The folded wings reached about halfway down the tail and close to level with the tips of the undertail-coverts (Plate 3). The tail had a slight but distinct fork (Plate 3). Plumage The breast, upper belly and flanks had a dirty-grey background colour that contrasted with the clean pale throat, half-collar, belly-stripe and ventral area. They were intensely marked with diffuse dark blotchy streaks that were poorly differentiated from the grey background (Plates 2–3). The blotches were generally short and wide (Plate 3), sometimes appearing to coalesce into longer streaks. The most distinct streaks were those nearest the throat, where they converged and ended sharply, giving the appearance of a black necklace (Plate 2). The flanks, especially the upper flanks, were dark and almost completely covered with diffuse coalescing blackish blotches. The centre of the belly was clean and pale, contrasting strongly with the flanks, and appearing as an inverted V. The ventral area was also clean and pale. The undertail-coverts appeared mainly pale in most views (Plate 3), but some photographs (not shown here) showed grey smudging towards the sides, with one VOL. 28 (1) marcH 2011 Dark-sided Flycatcher, Cocos (Keeling) Islands 3 or two discrete dark spots visible in one image. The undertail was dark (Plate 3) with small pale tips to the outer rectrices. Other than the brownish forecrown, the upperparts were dark grey. There was a prominent whitish wing-bar, formed by the tips of the greater coverts, and an inconspicuous thinner one formed from the tips of the median coverts. The primaries were uniformly grey-black. The secondaries were dark with white edges, which sometimes merged into a prominent longitudinal whitish bar. The tertials were dark grey-black with conspicuous whitish edges. The sides of the head were generally brownish grey. There was a prominent asymmetrical white eye-ring that extended much further posterior to the eye than anteriorly, appearing as a white, almost triangular patch (Plate 2). The lores were generally dark brownish grey, with a dirty, paler loral stripe that extended as a narrow line from above the upper mandible to the anterior edge of the eye-ring. This was underscored by a dark-brown line that continued downwards along the lower anterior edge of the eye-ring (Plate 2). There was a pale-grey submoustachial stripe that curved upwards towards the ear-coverts and a prominent dark malar stripe (Plate 3). The partial white collar extended around more than half the neck, beginning from the sides of the nape and continuing across the throat (Plate 2). When viewed laterally, it appeared as a bright white stripe, edged by the dark sides of the face and neck, giving the bird a hooded appearance. When viewed ventrally, it was sharply cut off from the dark upper-breast streaks, which almost coalesced below to form a near-continuous, sharply contrasting dark edge (Plate 3). The collar merged with the white throat and contrasted with the dark malar stripes. Identification The bird is readily identifiable as one of the brown Muscicapa flycatchers. Among this group, the species of broadly similar size, structure and plumage (and hence most likely to be confused with the Dark-sided Flycatcher) are the Grey- streaked Flycatcher M. griseisticta and Asian Brown Flycatcher M. dauurica (Clarke et al. 2009). Subspecies williamsoni and segregata of the latter (Brown-streaked Flycatcher and Sumba Brown Flycatcher) are sometimes accorded full species status but, for convenience, are treated here as subspecies of the Asian Brown Flycatcher. The Brown-streaked Flycatcher breeds from south-eastern Burma to the northern Malay Peninsula and winters south to Singapore, Sumatra and western Borneo (del Hoyo et al. 2006). Because it was thought unlikely to occur in Europe, it was not considered in the reviews by Alström & Hirschfeld (1991) and Bradshaw et al. (1991), but it is of interest here because of plumage variations between it and the more westerly subspecies of the Asian Brown Flycatcher. The Sumba Brown Flycatcher is resident on Sumba Island in the Lesser Sundas (del Hoyo et al. 2006), and is therefore very unlikely to occur in the Cocos (Keeling) Islands. Other species that might be confused with the Dark-sided Flycatcher include the Spotted Flycatcher and the Brown-breasted Flycatcher M. muttui. The former can be discounted as it shows distinctive black streaking on the forehead, crown and nape (Brazil 2009), which was absent in the Home Island bird, and a brownish (not white) eye-ring (Alström & Hirschfeld 1991).

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