8 An Apparent Dunlin x White-rumped Sandpiper Hybrid Kevin A. McLaughlin and Alan Wormington Near Point Pelee National Park, was a White-rumped Sandpiper (C. Ontario, at about 1600h on 18 May juscicollis), feeling that he had been 1994, McLaughlin approached a deceived by the bird's very close group of birders who were intently proximity of only 5 to 7 metres. studying a small group of Dunlin However, this assessment as to the (Calidris alpina) at Hillman Marsh, bird's identity still seemed some­ Essex County. The birds were feeding what wrong. The bill was clearly along the shore of a water body just more Dunlin-like in structure, and several feet from the main trail of in colour was entirely shiny black Hillman Marsh Conservation Area. right to its base. The base of the bill The object of scrutiny was an lacked any trace of yellow-brown unusual looking sandpiper that, at colour that would be characteristic first glance, was thought to be a of a White-rumped Sandpiper. Dunlin in prealternate molt. Furthermore, the upperparts However, several features were seemed wrong for a White-rumped, incorrect for that species. The bill, with too much rust edging to all of while resembling a Dunlin's in over­ the scapulars and tertials. The struc­ all structure, was much too short for ture of the bird was also odd for a a typical individual of that species. White-rumped, as it had rather The upperpart feathers were clearly short wings, a plump body, and legs alternate type, but were quite unlike that seemed too long for that those of a Dunlin as they lacked the species. extensive orange-red scapulars; While exclaiming "What the hell instead, these feathers were slate­ is this thing?" the truth was becoming centred with rusty sides and grayish clear to McLaughlin. Aware of the tips. The underparts were heavily bird's intermediate characters, he streaked on the breast, but the char­ stated in a somewhat incredulous acteristic large black belly patch of tone ofvoice: "This is a hybrid Dunlin an alternate-plumaged Dunlin was x White-rumped Sandpiper!" completely missing. Puzzled, and The apparent hybrid sandpiper being queried by several observers was observed regularly at the as to the bird's identity, McLaughlin Hillman Marsh location from 18 to then saw the bird raise its wings to 20 May inclusive, although occa­ reveal what appeared to be a white sionally it could not be found dur­ rump. He then stated that the bird ing this period. When present, the ONTARIO BIRDS APRIL 2000 9 Figure 1: Apparent Dunlin x White-rumped Sandpiper at Hillman Marsh, Essex County, 18 May 1994. Photo by Alan Wormington. bird was always with a flock of the tip. The bill was thick at the feeding Dunlins numbering about base, but tapered to a rather fine 10-15 birds. When feeding, the bird tip. It was about the length of the tenaciously defended a 5 metre bird's head, or perhaps two to two strip of shoreline from all intruding and a half times the loral distance, Dunlins. The proximity of the bird compared to that of a Dunlin's bill to a main trail, and its exceptional of three to three and a half times tameness, allowed it to be easily the loral distance. viewed and photographed by many observers, including Wormington. Head: The head had a steep fore­ head and a rounded crown. The DESCRIPTION crown was a mix of blackish and Bill: The bill was black. It was whitish streaks with a brown cast, slightly downcurved at its tip, particularly in the lateral crown recalling that of a Dunlin, but was area. There were fine black streaks perhaps only two-thirds the length on a whitish ground colour to the of that species' bill. The culmen was top of the bill. There was a broad, fairly straight, while the lower poorly defined white eyebrow with mandible was a bit downcurved at fine black streaks throughout. The VOLUME 18 UMBER 1 10 eyebrow broadened in the rear and (poorly defined) blackish bar ended at the nape. The lares were extending up the centre. white-based, with a heavy concen­ tration of fine black streaks and a Underparts: The underparts were bit of chestnut-brown near the bill white-based. The chin and throat base. The eyes were small and had fine black streaking. The breast appeared black. Quite striking were was heavily streaked/spotted black oval-shaped chestnut-brown patch­ with a number of black chevrons es behind and below the eyes in the extending down the side of the auriculars. The nape was a mix of belly to about the level of the legs. black and brown streaks. Some fine black streaks extended down the flanks to the undertail Upperparts: The mantle consisted coverts. There was no evidence of a of small black feather centres with black belly patch, the entire belly broad grayish edges. There were being white. two vague broad buff-white mantle lines. The forward-most upper Legs and Feet: These were a shiny scapulars were chestnut with small black, with the leg length perhaps a black centres. All of the remaining bit shorter than a Dunlin's. scapulars and tertials had solid black or dark brown centres with Size: In direct comparison to adja­ rusty sides to the feathers and cent Dunlins, the bird's overall abraded, broad, grayish-white tips. body size was slightly smaller. The exposed wing coverts appeared worn and were a dull brownish­ Vocalizations: Calls were heard on gray. The visible primaries appeared a number of occasions by faded brown. The primary tips Wormington. These consisted of a seemed to fall a few millimetres slightly raspy "chip" and an almost short of the tip of the tail. A thin squeal-like "creeep". These calls white wingstripe was evident when thus resembled one of the assumed the bird extended its wings, perhaps parent types, or a combination a bit narrower than that of a thereof. Dunlin. Age Determination: The faded Tail: The rectrices appeared slaty in brown colour on the visible folded colour, with a thin white fringe on primaries suggests that the bird was the outer edges and tip. The upper­ in first alternate plumage, with tail coverts were nearly all white recently acquired alternate scapu­ (resembling a White-rumped lars, mantle feathers and tertials Sandpiper) except for a few thin contrasting with worn nine month black streaks on the sides and a thin old primaries. ONTARIO BIRDS APRIL 2000 11 DISCUSSION sumed Baird's (c. bairdii) x Buff­ At the time of observation, the breasted (Tryngites subruficollis) authors were well aware of the Sandpiper in Massachusetts (Laux extreme rarity of hybrid shorebirds. 1994), an apparent Dunlin x Purple However, had it not been for the (C. maritima) Sandpiper in Great extreme tameness of this so-called Britain (Millington 1994), and a bird "Hillman Sandpiper" and its pres­ in Newfoundland thought to be a ence along a heavily-used trail, it is Pectoral x White-rumped Sandpiper quite probable that this bird would (Bain and Shanahan 1999). have gone undetected. Based on Armed now with the knowl­ this assumption, one could argue edge that hybrid shorebirds are that hybrid shorebirds in general produced occasionally, it seems might be going unnoticed on a reg­ likely that experienced shorebird ular basis. Only recently has it come observers will soon detect addition­ to light that the possibility of al examples of suspected hybrids encountering a hybrid shorebird is involving new combinations of more likely than once believed. adult types. There are, of course, several accounts describing the "Cox's Acknowledgements Sandpiper" in Australia (for exam­ Our thanks go to Ron Pittaway and ple, see Parker 1982), which has been Ron Tozer, who provided refer­ shown by Christidis et a1. (1996) on ences and made comments on a the basis of molecular analysis to be draft of the manuscript. a hybrid between Curlew Sandpiper (C. ferruginea) and Pectoral Literature Cited Sandpiper (c. melanotos). There is a American Ornithologists' Union. 1998. photographic record involving a sup­ Check-list of North American Birds. 7th edition. American Ornithologists' Union, posed juvenile Cox's Sandpiper from Washington, D.C. Massachusetts (Kasprzyk et a1. 1987, Bain, M. and D. Shanahan. 1999. Cross Vickery et a1. 1987), which has since Canada round-Up: August and September been disputed (Monroe 1991, 1999. Birders Journal 8: 210-228. Christidis, L., K. Davies, M. Westerman, P.D. American Ornithologists' Union Christian, and R. Schodde. 1996. Molecular 1998). "Cooper's Sandpiper," known assessment of the taxonomic status of from the unique type specimen Cox's Sandpiper. Condor 98: 459-463. taken in 1833 on Long Island, New Cox, J.B. 1989. Notes on the affinities of Cooper's and Cox's Sandpiper. South York, is believed to be a Curlew Australian Ornithologist 30: 169-18l. Sandpiper x Sharp-tailed Sandpiper Cox, J.B. 1990. The enigmatic Cooper's and (C. acuminata) hybrid (Cox 1989, Cox's Sandpipers. Dutch Birding 12: 53-64. 1990; Monroe 1991). Additional new Kasprzyk, M.J., R.A. Foster, and B.A. Harrington. 1987. First Northern or suspected hybrids to appear Hemisphere record and first juvenile recently on the scene include a pre- plumage description of the Cox's VOLUME 18 NUMBER 1 12 Sandpiper (Calidris paramelanotos). Parker, S.A. 1982. A new sandpiper of the American Birds 41: 1359-1364. genus Calidris. South Australian Naturalist Laux, E.V. 1994. Mystery sandpiper. Birding 56: 63. 26: 66-68. Vickery, P.D., D.W. Finch, and P.K. Donahue. Millington, R.