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An Apparent Dunlin x White-rumpedSandpiper Hybrid

Kevin A. McLaughlin and Alan Wormington

Near Point Pelee National Park,Ontario, at about 1600h on 18 May1994, McLaughlin approached agroup of birders who were intentlystudying a small group of Dunlin(Calidris alpina) at Hillman Marsh,Essex County. The birds were feedingalong the shore of a water body justseveral feet from the main trail ofHillman Marsh Conservation Area.

The object of scrutiny was anunusual looking sandpiper that, atfirst glance, was thought to be aDunlin in prealternate molt.However, several features wereincorrect for that species. The bill,while resembling a Dunlin's in over­all structure, was much too short fora typical individual of that species.The upperpart feathers were clearlyalternate type, but were quite unlikethose of a Dunlin as they lacked theextensive orange-red scapulars;instead, these feathers were slate­centred with rusty sides and grayishtips. The underparts were heavilystreaked on the breast, but the char­acteristic large black belly patch ofan alternate-plumaged Dunlin wascompletely missing. Puzzled, andbeing queried by several observersas to the bird's identity, McLaughlinthen saw the bird raise its wings toreveal what appeared to be a whiterump. He then stated that the bird

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was a White-rumped Sandpiper (C.juscicollis), feeling that he had beendeceived by the bird's very closeproximity of only 5 to 7 metres.However, this assessment as to thebird's identity still seemed some­what wrong. The bill was clearlymore Dunlin-like in structure, andin colour was entirely shiny blackright to its base. The base of the billlacked any trace of yellow-browncolour that would be characteristicof a White-rumped Sandpiper.Furthermore, the upperpartsseemed wrong for a White-rumped,with too much rust edging to all ofthe scapulars and tertials. The struc­ture of the bird was also odd for aWhite-rumped, as it had rathershort wings, a plump body, and legsthat seemed too long for thatspecies.

While exclaiming "What the hellis this thing?" the truth was becomingclear to McLaughlin. Aware of thebird's intermediate characters, hestated in a somewhat increduloustone of voice: "This is a hybrid Dunlinx White-rumped Sandpiper!"

The apparent hybrid sandpiperwas observed regularly at theHillman Marsh location from 18 to20 May inclusive, although occa­sionally it could not be found dur­ing this period. When present, the

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Figure 1: Apparent Dunlin x White-rumped Sandpiper at Hillman Marsh, EssexCounty, 18 May 1994. Photo by Alan Wormington.

bird was always with a flock offeeding Dunlins numbering about10-15 birds. When feeding, the birdtenaciously defended a 5 metrestrip of shoreline from all intrudingDunlins. The proximity of the birdto a main trail, and its exceptionaltameness, allowed it to be easilyviewed and photographed by manyobservers, including Wormington.

DESCRIPTIONBill: The bill was black. It wasslightly downcurved at its tip,recalling that of a Dunlin, but wasperhaps only two-thirds the lengthof that species' bill. The culmen wasfairly straight, while the lowermandible was a bit downcurved at

the tip. The bill was thick at thebase, but tapered to a rather finetip. It was about the length of thebird's head, or perhaps two to twoand a half times the loral distance,compared to that of a Dunlin's billof three to three and a half timesthe loral distance.

Head: The head had a steep fore­head and a rounded crown. Thecrown was a mix of blackish andwhitish streaks with a brown cast,particularly in the lateral crownarea. There were fine black streakson a whitish ground colour to thetop of the bill. There was a broad,poorly defined white eyebrow withfine black streaks throughout. The

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eyebrow broadened in the rear andended at the nape. The lares werewhite-based, with a heavy concen­tration of fine black streaks and abit of chestnut-brown near the billbase. The eyes were small andappeared black. Quite striking wereoval-shaped chestnut-brown patch­es behind and below the eyes in theauriculars. The nape was a mix ofblack and brown streaks.

Upperparts: The mantle consistedof small black feather centres withbroad grayish edges. There weretwo vague broad buff-white mantlelines. The forward-most upperscapulars were chestnut with smallblack centres. All of the remainingscapulars and tertials had solidblack or dark brown centres withrusty sides to the feathers andabraded, broad, grayish-white tips.The exposed wing coverts appearedworn and were a dull brownish­gray. The visible primaries appearedfaded brown. The primary tipsseemed to fall a few millimetresshort of the tip of the tail. A thinwhite wingstripe was evident whenthe bird extended its wings, perhapsa bit narrower than that of aDunlin.

Tail: The rectrices appeared slaty incolour, with a thin white fringe onthe outer edges and tip. The upper­tail coverts were nearly all white(resembling a White-rumpedSandpiper) except for a few thinblack streaks on the sides and a thin

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(poorly defined) blackish barextending up the centre.

Underparts: The underparts werewhite-based. The chin and throathad fine black streaking. The breastwas heavily streaked/spotted blackwith a number of black chevronsextending down the side of thebelly to about the level of the legs.Some fine black streaks extendeddown the flanks to the undertailcoverts. There was no evidence of ablack belly patch, the entire bellybeing white.

Legs and Feet: These were a shinyblack, with the leg length perhaps abit shorter than a Dunlin's.

Size: In direct comparison to adja­cent Dunlins, the bird's overallbody size was slightly smaller.

Vocalizations: Calls were heard ona number of occasions byWormington. These consisted of aslightly raspy "chip" and an almostsqueal-like "creeep". These callsthus resembled one of the assumedparent types, or a combinationthereof.

Age Determination: The fadedbrown colour on the visible foldedprimaries suggests that the bird wasin first alternate plumage, withrecently acquired alternate scapu­lars, mantle feathers and tertialscontrasting with worn nine monthold primaries.

DISCUSSIONAt the time of observation, theauthors were well aware of theextreme rarity of hybrid shorebirds.However, had it not been for theextreme tameness of this so-called"Hillman Sandpiper" and its pres­ence along a heavily-used trail, it isquite probable that this bird wouldhave gone undetected. Based onthis assumption, one could arguethat hybrid shorebirds in generalmight be going unnoticed on a reg­ular basis. Only recently has it cometo light that the possibility ofencountering a hybrid shorebird ismore likely than once believed.

There are, of course, severalaccounts describing the "Cox'sSandpiper" in Australia (for exam­ple, see Parker 1982), which has beenshown by Christidis et a1. (1996) onthe basis of molecular analysis to bea hybrid between Curlew Sandpiper(C. ferruginea) and PectoralSandpiper (c. melanotos). There is aphotographic record involving a sup­posed juvenile Cox's Sandpiper fromMassachusetts (Kasprzyk et a1. 1987,Vickery et a1. 1987), which has sincebeen disputed (Monroe 1991,American Ornithologists' Union1998). "Cooper's Sandpiper," knownfrom the unique type specimentaken in 1833 on Long Island, NewYork, is believed to be a CurlewSandpiper x Sharp-tailed Sandpiper(C. acuminata) hybrid (Cox 1989,1990; Monroe 1991). Additional newor suspected hybrids to appearrecently on the scene include a pre-

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sumed Baird's (c. bairdii) x Buff­breasted (Tryngites subruficollis)Sandpiper in Massachusetts (Laux1994), an apparent Dunlin x Purple(C. maritima) Sandpiper in GreatBritain (Millington 1994), and a birdin Newfoundland thought to be aPectoral x White-rumped Sandpiper(Bain and Shanahan 1999).

Armed now with the knowl­edge that hybrid shorebirds areproduced occasionally, it seemslikely that experienced shorebirdobservers will soon detect addition­al examples of suspected hybridsinvolving new combinations ofadult types.

AcknowledgementsOur thanks go to Ron Pittaway andRon Tozer, who provided refer­ences and made comments on adraft of the manuscript.

Literature CitedAmerican Ornithologists' Union. 1998.

Check-list of North American Birds. 7thedition. American Ornithologists' Union,Washington, D.C.

Bain, M. and D. Shanahan. 1999. CrossCanada round-Up: August and September1999. Birders Journal 8: 210-228.

Christidis, L., K. Davies, M. Westerman, P.D.Christian, and R. Schodde. 1996. Molecularassessment of the taxonomic status ofCox's Sandpiper. Condor 98: 459-463.

Cox, J.B. 1989. Notes on the affinities ofCooper's and Cox's Sandpiper. SouthAustralian Ornithologist 30: 169-18l.

Cox, J.B. 1990. The enigmatic Cooper's andCox's Sandpipers. Dutch Birding 12: 53-64.

Kasprzyk, M.J., R.A. Foster, and B.A.Harrington. 1987. First NorthernHemisphere record and first juvenileplumage description of the Cox's

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Sandpiper (Calidris paramelanotos).American Birds 41: 1359-1364.

Laux, E.V. 1994. Mystery sandpiper. Birding26: 66-68.

Millington, R. 1994. A mystery Calidris atCley. Birding World 7: 61-63.

Monroe, B.L. Jr. 1991. A reconsideration ofthe Massachusetts "Cox's Sandpiper".American Birds 44: 232-233.

Parker, S.A. 1982. A new sandpiper of thegenus Calidris. South Australian Naturalist56: 63.

Vickery, P.D., D.W. Finch, and P.K. Donahue.1987. Juvenile Cox's Sandpiper (Calidrisparamelanotos) in Massachusetts, a firstNew World occurrence and a hithertoundescribed plumage. American Birds 41:1366-1369.

Figure 2: Presumed Dunlin x White-rumped Sandpiper at Hillman Marsh, EssexCounty, 19 May 1994. Photo by Alan Wormington.

Kevin A. McLaughlin, 30 Bingham Road, Hamilton, Ontario L8H 1N4

Alan Wormington, R.R. 1, Leamington, Ontario N8H 3V4

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