MARCH,1989

NOTES ON THE AFFINITIES OF COOPER'S AND COX'SSANDPIPERS

JOHN B. COX

169

SUMMARY

COX, J. B. 1989. Notes on the affinities of Cooper's andCox's Sandpipers. S. Aust. Om. 30: 169-181.

The affinities of Calidris cooperi, known from onespecimen collected in eastern North America in 1833, areobscure. Some writers of the last century suggested that C.canutus or C.fuscicollis were the closest relatives of cooperi.C. paramelanotos was described in 1982 from two SouthAustralian specimens,but it has been suggested that they mayin fact be hybrids between C. ferruginea and C. melanotos.A reassessment of the characters of cooperi andparamelanotos shows them to be morphologically similar,though differing in the coloration and markings of theirunderparts. Their characteristics suggest that they are relatedto a group of calidritine sandpipers that have polygynous orpromiscuous mating systems: fuscicollis, ferruginea,acuminata and melanotos. I conclude that cooperi andparamelanotos probably are hybrids of parent species fromwithin that group of calidritines.

INTRODUCTIONThe unique specimen of Cooper's Sandpiper

Calidris cooped was collected at Raynor South,Long Island, New York, United States ofAmerica, on 24 May 1833 by W. Cooper (Baird1858). It is in the United States National Museumof Natural History (USNM), Washington, D.C.

The relationships of cooped have remainedobscure. Baird (1858: 716-717) thought its affini­ties were perhaps closest to the Red Knot Ccanutus. Ridgway(1887: 157), however, disagreed,regarding its relationships to lie rather with theWhite-rumped Sandpiper C fuscicollis, whileSeebohm (1888: 423) placed it without commentin the synonymy of canutus. Elliot (1895: 79),seemingly the first to suspect cooperi not to bea distinct species, thought it very doubtfulwhether the type represented anything more thanan unusually largejuscico/lis or possibly a hybridbetween that species and the Pectoral SandpiperC melan0 tos. Ridgway (1919: 289-290) wrote,''The relationship of this bird, the type of whichremains unique, is distinctly with P. fuscicollis,from which it could hardly be distinguished butfor its decidedly greater size, all its measurementsexceeding the maximum of them of P.fuscicollis.It needs no comparison with Canutus canutus,

the coloration, in toto, and the proportions beingvery different." EA. Pitelka (pers. comm., 28October 1988) considers that if cooped is a hybridthe- monogamous mating system and displaybehaviour of canutus rule out the possibility ofit being a parent.

In 1977,S. A. Parker, Curator of Birds, SouthAustralian Museum (SAM), and ,Inoted that twostrange sandpipers recently collected in SouthAustralia had some features 'reminiscent of.Sharpe's (1896) brief description of cooped.Parker subsequently sent the specimens to theUSNM for comment and comparison with thespecimen of cooped. In correspondence of 1977and 1978he was informed that they were not the'same as cooped (Cox 1989).

Parker's (1982) description of Cox's SandpiperC. paramelanotos was based on these same twospecimens: SAM reg. no. B28843 (paratype),Mosquito Point, Lake Alexandrina, 16February1975, collected by H. J. Eckert and me; andB30775 (holotype), which I collected at PriceSaltfields, Upper Yorke Peninspla on 5 March1977. These specimens and other non-specimenrecords from Australia were later described indetail (Cox 1987). All these were of adult birdsin non-breeding plumage or pre-nuptial moult.

Because the only previous reports ofparamelanotos were from Australia, it wassurprising that the first Northern Hemisphererecord attributed to this form should have beenfrom the Atlantic coast of North America',where the specimen of cooperi was collected. Thislater record of paramelanotos, a juvenile trapped,photographed and observed at Duxbury Beach,Massachusetts, 15-21 September 1987, wasdescribed and discussed by Forster (1987),Kasprzyk et at. (1988) and Vickery et at. (1988).Kasprzyk et at. (1988) also noted, "Many of the,plumage characters of Cooper's Sandpiper:(Ridgway 1919) resemble those of Cox's Sand­piper"; but they and Buckley (1988) consideredcooped and paramelanotos not to be the same.Mudd (1988) described another sighting of anunusual sandpiper, at Little Creek Wildlife Area,

170 SOUTH AUSTRALIAN ORNITHOLOGIST, 30

Delaware, 13 September 1987. He considered itstrongly possible that it too was an example ofparamelanotos.

Despite these sightings, paramelanotos is anenigma. Its breeding grounds are unknownalthough Marchant et al. (1986) suggested thatthey were ''probably in the USSR." Also, itsspecific status has been questioned. C.paramelanotos most closelyresemblesthe CurlewSandpiper C. ferruginea and C. melanotos, andmay in fact be their hybrid progeny (Cox 1987)2.

Thus cooped and paramelanotos are very rarebirds of unknown natal origin. Moreover, theyshare some morphological features. In thefollowing, their characteristics are re-examinedand reassessed.

MATERIALS AND. METHODSThe two specimens of C. paramelanotos, and

specimens of C. canutus, C. fuscicollis, Baird'sSandpiper C. bairdii, C. melanotos, Sharp-tailedSandpiper C. acuminata, Dunlin C. alpina andC.ferruginea wereexamined and compared in theSouth Australian Museum. Fifteen colour slides(35mm transparencies) of the holotype of C.cooped were studied through the courtesy of R.L. Zusi, (USNM).

Because of the dearth of specimens, this studyof cooperi and paramelanotos has also usedsight-records. Though unverifiable, except byphotography, which also has its limitations, theseare to date the only additional source of dataavailable. Six sight records of paramelanotosweredescribed (Cox 1987), and since then I have seenthree other paramelanotos at I.C.I. Saltfields,Adelaide, South Australia: an adult in wornnuptial plumage on 29 August 1987; an adult innon-breeding plumage seen many times from 22November 1987 to 13February 1988; and anotheradult in non-breeding plumage on 24 and 30January 1988. C. R. Corben has also generouslysupplied his unpublished field descriptions ofsingle birds seen by him and others at WerribeeSewageFarm, Victoria, on 4 March 1979 and 17February 1981. Photographs of paramelanotospublished in articles by Grant (1987), Kasprzyket al. (1988), Vickery et al. (1988) and Buckley(1988) were also studied.

RESULTSPlumage and sex of specimens

The specimen of cooperiis in remarkably goodcondition, considering that it was collected in

1833, though some upper tail-coverts and feathersof the back and rump appear to be missing.Ridgway (1919) described it as an 'Adult male insummer (sex not determined [sic])", and initiallyI thought it to be an adult in worn nuptialplumage. However, closer study of the colourslides revealed that feathers of non-breeding andnuptial plumages are present, and it seems thebird had partly moulted into nuptial plumagewhen it was collected. Indeed, Baird (1858) noted,"There are severalscapular feathers which appearto be assuming a more perfect dress."

Both specimens of paramelanotos are in pre­nuptial moult. They have feathers of non­breeding and nuptial plumage (Cox 1987). Theholotype is an adult male (Parker 1982). Theparatype, also an adult, was sexed tentatively asa male, but should be properly regarded as ofunknown sex (Cox 1987); its markedly smallerdimensions led Parker (1982) to suspect itopposite in sex from the holotype,

MeasurementsKasprzyk et al. (1988) considered recently taken

measurements of cooped to be nearly identical tothose given by Ridgway (1919). Baird's (1858)measurements of the specimen werein inches, butthey are compatible with those of Ridgway, whogave them in millimetres. Table 1 comparesRidgway's measurements of cooperi withmeasurements of paramelanotos.

Table 1. Measurements of cooped (from Ridgway1919) and paramelanotos(from Parker 1982), andthose taken from live birds (from Lane et al. 1981and Kasprzyk et al. 1988).

Wing Tail Tarsus Culmencooperi 146 57 29 31paramelanotosSpecimens

Mosquito Point, S.A. 134 30.1 32.5Price Saltfields, S.A. 144 57.3 31.5 37.3

Live birdsNew South Wales 137 54 34.5Massachusetts, U.S.A. 35.1---_._----- ---------

C. cooperi has a longer wing and shorterculmen and tarsus than paramelanotos. Even so,its measurements are very close to those ofparamelanotos. The difference of 2 mm in winglength between cooped and the longer-winged ofthe two paramelanotos is probably notsignificant, especially when so few data areavailable (and when there is, normally, variation

MARCH,1989 171

amongst measurements taken by differentworkers and even one worker at different times).The tarsal length of cooperi is also probably notsignificantly different from that of paramel­anotos - a little more than 1 mm shorter thanthat of the smaller of the two paramelanotos, andwithin the range of tarsal measurements offerruginea, melanotos and acuminata listed inPrater et at. (1977). Buckley (1988) stated, "Cox'starsus is absolutely longer than that of thePectoral". This is incorrect because, in fact, theirtarsal measurements overlap (Parker 1982; Cox1987).The bill of cooperi is 1.5 mm shorter thanthe bill of the smaller paramelanotos, and isintermediate in length between the bills offerruginea and melanotos (as withparamelanotos, Cox 1987), or ferruginea andacuminata.

Coloration of unfeathered parts and bill-shape

Kasprzyk et at. (1988) ruled out the possibilitythat cooperi was the same as paramelanotos, forreasons that included, ''The legs and bill [ofcooperii appeared as if they were originallydarkish throughout; most importantly, the billwas not decurved as in Cox's Sandpiper."

When the two specimens of paramelanotoswere collected, they had dark olive legs and asmall yellowish area at the extreme base of thelower mandible of otherwise black bills (Cox1976, 1987; Parker 1982). Both dried skins nowhave blackish legs and wholly black bills.Therefore it is unlikely that the present colorationof unfeathered parts can be used to distinguishcooperi from paramelanotos.

Baird (1858) described the bill of cooperi asstraight, approaching in this character melanotosandfuscicollis. Although many early writers havesimilarly described Calidris sandpipers as havingstraight bills, all typical members of the genushave, at the very least, the bill faintly decurvedterminally. It is now well-known that melanotos,as stated by Marchant et al. (1986), has a "slightly­decurved" or "faintly-decurved" bill, and thatfuscicollis has a "slightly drooping" bill. Whendescribing the first specimen of paramelanotosas an unusual specimen of melanotos, I noted(Cox 1976) that the longer the bill in bothmelanotos and acuminata, the greater itsdecurvature.

The bill of the holotype of cooperi (Figs. lAand 2) has small, semicircular notches near the

tip, possibly caused by fine shot. Its uppermandible is bent upwards for a quarter of itslength from the tip, whereas the lower mandibleis evenly decurved. Also, both mandibles meetcorrectly at the base of the bill, but the tip of theupper extends well past the tip of the lower. Ifthese shapes obtained when the bird was living,it would not have been able to close its billproperly. Moreover, even if the bill had originallybeen straight, the tips of the mandibles would stillhave been out of alignment. When the bird wasliving, the upper mandible was probably slightlydecurved to match the lower mandible (Fig. lB,cj. paramelanotos, Fig. 3). Presumably, post­mortem changes are responsible for the presentdistortion of the bill.

Markings of the head and neck

C. cooperi and paramelanotos have verysimilar markings on the head and neck: theground colour whitish to buff with a rusty wash,and with heavy dark brown or blackish streaks.The pale supercilium of cooperi is horizontallydivided by a line of dark streaks (Fig. 1). Theresulting effect of a split supercilium is not notice­able in the specimens of paramelanotos, but wasremarked on other birds (Cox 1987, and Fig. 3)..

The pattern of streaks on the head of cooperiis very similar to that of a bird trapped andphotographed by Lane et al. (1981) at Stockton,New South Wales, which they considered to bea hybridferruginea x acuminata. C. melanotosalso has similar head markings, but ferrugineaand acuminata are not so heavily streaked on thehead and have a broad pale supercilium extendingbehind the eye (Cox 1987). Two fuscicollis innuptial plumage (SA.l\1 B28089and B28090)havefiner head mar kings.Upperparts

Baird (1858) noted the nuptial plumagescapulars of cooperi to be "...black, abruptlyedged laterally with pale rusty, passing towardsthe tip into ashy". They are of the same patternand colour (Fig. 4) as those of paramelanotos(Fig. 2 in Cox 1987). The scapulars, mantlefeathering and wing-coverts of non-breedingplumage on the specimen of cooperi alsoresemble those of paramelanotos, which are"grey-brown with black shafts and whitishfringes" (Cox 1987).

The tertials of cooperi are blackish withwhitish to buff edgings, and are similar to the

172 SOUTH AUSTRALIAN ORNITHOLOGIST, 30

Rump and upper tail-coverts

When diagnosing parame/anotos againstme/anotos, Parker (1982) wrote, ''the feathers ofthe rump blackish-brown (not black) withbroader pale fringes, the median upper tail­coverts not black but whitish washed pale grey­buff and marked with heavy blackish-brown barsand chevrons". I wrote (Cox 1987), ''This feather

though in some the inner primary shafts weredarker, contrasting with the whitish tenth primaryshaft as in me/anotos and parame/anotos.

Ridgway (1919) said that cooperi has "shaftsof primaries white post-medially, passing intograyish brown basally and terminally". The tenthprimary shaft of cooperi is the only one visiblein the colour slides. It is brownish towards thebase of the upper surface, and therefore it seemsthat in cooperi the coloration of the primaryshafts is similar to that of acuminata rather thanthat of me/anotos.

Figure 1. (A) Head and bill of the specimen of cooperi. Note the upward bend to the upper mandible, and distorted positionof the eye.Photo: courtesy ofR.L. Zusi, USNM. (B) A reconstruction of the head and bill of cooperi, showing the probableappearance of the specimen in life. Compare the pattern of head streakings with photograph of a trapped bird in Laneet aJ. (1981).

tertials with ''buff edges" on the bird describedby Lane et al. (1981). Parker (1982) described thefringes of the mantle, back, scapulars and tertialsof parame/anotos as "a brighter, more gingerybrown" than those of me/anotos in basic (non­breeding) plumage (having been misled into notregarding these as new feathers of a pre-nuptialmoult by their light degree of wear). Aparame/­anotos in non-breeding plumage was noted tohave whitish fringes to its tertials, later changingduring pre-nuptial moult to bright rufous (Cox1987).Coloration ofprimary shafts

C. parame/anotos resembles me/anotos in thepigmentation of the primary shafts. The uppersurfaces of all shafts are brownish except thetenth, which is whitish (Parker 1982; Cox 1987).The primary shafts of acuminata are whitishshading to greyish near the base (Cox 1987).Specimens of ferruginea examined had primaryshaft coloration similar to that of acuminata,

MARCH,l989 173

Figure 2. Dorsal viewsof the bills of C. melanotos (upper) and C. cooperi (lower). Note that the bill of cooperi has a narrowerbase but is slightly longer than that of melanotos. Their bill-tips are equal in width; the bulge on the left-hand side nearthe tip of the bill of cooperi is part of the lower mandible that is not in natural alignment. Photo: courtesy oj R.L. Zusi, USNM

coloration could also suggest intermediacybetween melanotos, which has the same feathersblackish, andjerruginea, on which they are whitethough with an occasional dark bar."

Of cooperi, Baird (1858) remarked: "The uppertail coverts are white, each one with a V-shapedmark of brown; the rump feathers are brown,edged with whitish." Therefore, while cooped hasrump feathers similarly coloured to those ofparamelanotos, the pattern of the upper tail­coverts needs clarification.

The colour slides of cooped show some rumpfeathers and upper tail-coverts displaced andothers missing. Some of the most central uppertail-coverts are whitish with a broad, blackishsubterminal band extending briefly along theshaft to a point towards the tip, and the lateralupper tail-covertshave a thin, blackish line alongthe shaft from which a thicker, diagonal bartapers outwards to a point near the edge of eachfeather (Fig. 5A). These markings are only super­ficially V-shaped, and are not the same as the V-

shaped markings on the upper tail-coverts ofcanutus(Fig. 5q, as was believedby Baird (1858).Instead, they appear to be a mixture of themarkings on the upper tail-coverts of nuptiallyplumagedjerruginea and acuminata: the broad,blackish subterminal bars of the most centralfeathers are similar to those of ferruginea (Fig.5E), whereas the black lines along the shaftsand tapering diagonal bars resemble those ofacuminata (Fig. 5D), or are a combination of themarkings on the lateral upper tail-coverts offerruginea and acuminata.

The upper tail-coverts of nuptiallyplumagedferruginea are whitish, each feather having ablackish subterminal bar and another blackishbar (often broken) towards the base (Fig. 5E), thelatter usually hidden by an overlying feather.Both specimens of paramelanotos have someupper tail-coverts with similar markings (Fig.5B). It cannot be ascertained from the colourslides of cooped whether that specimen has anyupper tail-coverts with two bars.

174 SOUTH AUSTRALIAN ORNITHOLOGIST, 30

C me/anotos has whitish lateral upper tail­coverts, with a blackish V-shaped central markingacross both webs of some feathers (Fig. 5F). Cparame/anotos has lateral upper tail-coverts withsimilar markings (Fig. 5B).

In summary, cooped has some upper tail­coverts similar to those of ferruginea andacuminata, and parame/anotos has some similarto those of ferruginea and me/anotos.

One colour slide of cooped shows the general ­pattern of the rump and upper tail-coverts (Fig.6). There is a large white area on either side ofthe dark, lower central rump feathers. Whenperfect, the pattern would probably haveconsisted of a dark central stripe, barred paler,with large white areas on either side, bordered bythe blackish central markings of the lateral uppertail-coverts.

TailThe tail-shape ofparame/anotos resembles that

of me/anotos: the rectrices have rounded tipsexcept the longer central pair, which are pointed(Parker 1982; Cox 1987). In acuminata all of therectrices are pointed, though again the centralpair are longer.than the rest. lu ferruginea they

are rounded, with the central pair being onlyslightly longer and more pointed than the outerfeathers (illustrated by Bruns 1986). Judging fromthree specimens of fuscicollis examined, I notethat it has rectrices of similar shape and colourto those of ferruginea.

Baird (1858) wrote of cooped, "Tail doublyemarginate, but the central feathers projecting butslightly." The slight projection of the central pairis discernible in one colour slide of the specimen;however, they do not appear to project as far, orto be so pointed, as the central pair ofparamelan­otos, me/anotos and acuminata. Also shown inthe colour slide of cooperi is the rounded tip ofan outer rectrix (Fig. 6). Thus all of its rectricesseem to resemble those of ferruglnea andfuscicollis.

Underparts

Parker (1982) distinguished parame/anotosfrom me/anotos in non-breeding plumage by theformer's pectoral zone being lighter, less clearlydemarcated, and with a rusty wash. Conversely,I noted (Cox 1987) parame/anotos to have a''heavily streaked breast sharply demarcated fromwhite lower breast and rest of underparts" (seeFig. 3).

Figure 3. C. paramelanotos, I.C.1. Saltnelds, South Australia, 3 January 1987. Note the slightly decurved bill, melanotos­like breast streakings and the 'split supercilium '. Photo: D. W. Eades.

MARCH,1989 175

Figure 4. Scapulars of cooperi from colour slides of specimen...Diagonal shading represents brighter rufous coloration, andstippling is shades of grey. Note badly frayed edges to all feathers; two on left of nuptial plumage and that on right ofnon-breeding plumage. Compare with scapulars of paramelanotos (Figure 2 in Cox 1987).

Baird (1858) described thus the underparts ofcooped: ''The lower part of the neck, thejugulum, and the sides of the body, show elonga­ted oval spots of brown, not much crowded, butvery welldefined. These blotches under the wingsare rather V-shaped, but where exposed are onlyin the end of the feather."

The ventral markings of cooped (Fig. 7) greatlyresemble those of acuminata when in pre-nuptialmoult. Indeed, two specimens of acuminata(SAM B285 and B36526) have ventral markingsalmost the same as those of cooped. Theunderparts of two nuptially plumagedjuscicollis(SAM B28089 and B28090) differ markedly from

A 8J\

L C

830775

·E F

R L L

B36524 B7997 B32120

Figure 5. Upper tail-coverts of some Calidris sandpipers (not to scale); L -Ieft lateral, C - central, R - right lateral. Drawingsfrom colour slide of cooperi (A) and specimens in the South Australian Museum (registration numbers given):paramelanotos(B), canutus (C), acuminata (D), ferruginea (E), and melanotos (F).

176 SOlJTH AUSTRALIAN ORNITHOLOGIST, 30

Figure 6. The rump, upper tail-covertsand tail of C cooperi. Note that some upper taii-covertsseem to be missing, in particularsome central ones. Also, note that the most central upper tail-coverts have a blackish subterminal bar, and that the lateralcoverts have a diagonal bar tapering 'outwards from a blackish shaft line. These markings are superficiallyV-shaped. In perfect plumage, the most anterior of the right-hand lateral upper tail-coverts (and some on the left) wouldbe partly beneath an overlying feather and only the lower half of the black diagonal bar would then be visible.Photo: courtesyof R.L. Zusi, USNM.

Figure 7. The ventral markings of C cooperi. Note the diffuse gorget of dark brown streaks and spots on the upperbreast, and triangular spots and bars on the flanks. Photo: courtesy of R. L. Zusi, USNM.

MARCH, 1989 177

those of cooped in having the blackish breast­spots densely clustered on a grey ground devoidof any rusty wash.

The holotype of cooperi has a small whitisharea on the throat, marked by only a few darkspeckles and bordered by the heavy rustilywashed streaking of face and neck. The heavystreaks of the lower neck widen towards the upperbreast, forming a diffuse, rusty-washed gorget.Below this band the markings are sparser, butlarger, consisting of dark brown oval blotches ona whitish-buff ground. On the lower breast themarkings are thinner, more scattered, streaks; onthe whitish-buff plumage of the belly they areabsent altogether. On the sides of the breast occurdark brown streaks and triangular blotches thattowards the flanks merge into sparser but broaderV-shaped bars. Some lower flank feathers aremarked brown alongside the shaft, from whicha brown diagonal bar tapers outwards. The lateralunder tail-coverts are whitish with some brownstreaks and chevrons in the centres.

Thus, the ventral markings of cooped clearlydiffer from those of paramelanotos. However, C.R. Corben (pers. comm., 9 March 1988) haskindly supplied descriptions and drawings offeathers of birds (later identified by him asparamelanotos and possibly involving only oneindividual) seen by him at Werribee SewageFarm,Victoria, on 4 March 1979and 17February 1981.His field notes of the underparts of the first birdread:

''Belly white, flanks with sparse brown streaks (fine) andbars more anteriorly. Breast and throat washed with palebrown and finely spotted, more conspicuous anteriorly.

This gavethe appearance of a verypoorly-defined duskygorget. Darker spots rather irregular, giving the effect thatthey were hidden by pale tips to feathers. ie: rather likefresh RNS [Red-neckedStint C. rujico//is] pectoral band."

His notes on the second bird read:

''Front of neck likesides of neck with fine blackish streaks,but these giving way further down to a more barredappearance which extended well down towards belly.Flanks also appeared slightly barred with grey but somedarker feathers just visible.

Back of breast [i.e. "the lower sides of the breast oranterior flanks where the feathers often overlap the wingon a bird at rest"] with faint buff tinge. Chin whitish.Breast (including back [of breast]) with dark centres tofeathers givingfinely streaked appearance (fine likein sidesof STS [acuminata] breast). Flanks and lower breast withbroadish subterminal blackish bars giving an arrow-headpattern, mostly hidden by white tips. Such marks

overlapped the streakings on lower breast. No definedcontrast on chest. Fine blackish streaks on rear flanks andlateral undertail coverts."

Nuptial plumage

In their ventral markings, the birds describedby Corben appear to have been similar to coopedrather than to paramelanotos. However, thespecimen of cooperi was collected later in the yearthan either specimen of paramelanotos. It ispossible therefore that the dark speckles notedon the sides of the breast of two paramelanotos(Cox 1987)could have later enlarged with feather­growth, and markings similar to those of coopedmight have appeared on their breasts and flanks.Indeed, a paramelanotos photographed inVictoria in March 1986 (Grant 1987) had somespots on the breast.

Nevertheless, it seems that there are two differ­ent nuptial plumages, one like cooperi and thebirds described by Corben, and another, exempli­fied by a bird photographed by A. F. Lees andme at I.C.I. Saltfields, South Australia, on 4 April1987. The latter bird was in pre-nuptial moult andhad head, neck and breast coloration suggestiveof a hypothetical hybridjerruginea x melanotos.Unfortunately, the colour slides are not suitablefor reproduction, but when projected andenlarged on a screen, they show the bird'smarkings well enough. It had streaks on thecrown, facial region, neck and breast, all heavilywashed orange-brown. This colour was particu­larly noticeable on the ear-coverts, neck andbreast, below which it gradually merged into thewhitish belly.

On 29 August 1987I saw a paramelanotos thatappeared to be in worn nuptial plumage at I.C.I.Saltfields. Its scapulars were the same pattern andcolour as those of the two collected specimens,but the grey tips were reduced in extent becauseof plumage wear. Also, its primaries were wornand brownish, and distinct from the newprimaries of juveniles. It was similar to the birdseen on 4 April 1987 and, indeed, it could havebeen the same individual. Its head, neck andbreast were however a rich orange-buff insteadof orange-brown, a difference possiblyattributable to the effects of wear.Juveniles

The juvenile bird seen in Massachusetts,U.S.A., in September 1987 was identified asparamelanotos by Kasprzyk et at. (1988), Vickeryet al. (1988) and Buckley (19~8). I am unable to

178 SOUTH AUSTRALIAN ORNITHOLOGIST, 30

ascertain, however, why it could not have beena juvenile cooped, which is undescribed.

Vickeryet al. (1988) listed six characters of theMassachusetts juvenile that they noted as beingabsent in juvenile specimens of jerruginea andmelanotos examined, concluding, 'These we offeras new evidence that Cox's Sandpiper is not aPectoral and Curlew hybrid, and is probably aspecies."

The six characters are, however, intermediatebetween those of juvenilejerruginea and juvenilemelanotos or are found on juveniles of bothspecies. The pointed centres in some scapularsand wing-coverts are found on some juvenilemelanotos (Plate 6 in Prater et al. 1977). Theanchor-shaped centres of the lower scapulars,pale greycentres to wing-coverts and subterminaldarkening of inner secondary coverts are inter­mediate between the grey feathers with a blackishsubterminal band and dark line along the shaft(producing the anchor shape noted by Vickeryet al. 1988) of juvenile jerruginea and the dark­centred feathers of juvenile melanotos (seePlates4 & 6 of Prater et al. 1977). The description ofmore prominent rufous bars on the lower back,though subjective, possibly indicates a combina­tion of the thin whitish fringes to those feathersof juvenilejerruginea and the thin rufous fringesof juvenile melanotos. Finally, the split super­cilium extending well behind the eye is foundequally prominently in some juvenilejerruginea(p-hotograph in Anon. 1987), and sometimesfaintly in juvenile melanotos (Marchant et al.1986).

outwardly appear to be hybrids ofjerruginea andmelanotos (such as those described in Cox 1987)may in fact be hybrids of jerruginea andacuminata. e. acuminata in non-breedingplumage has a greyish breast finely streaked withbrown, and may show a darkish breast band(Marchant et al. 1986), and some non-breedingplumagedjerruginea have a streaked breast bandthat is sharply demarcated from the remainingwhite ventral regions (e.g, SAM B25989). Thusa hybrid could have ventral markings thatresemble those of melanotos.

e. cooped and paramelanotos chiefly differ intheir ventral markings. Otherwise, they havemany features in common that suggest it unlikelythat each is a distinct species. The holotype ofcooped has long wings like the holotype ofparamelanotos and males of melanotos, whereasjerruginea and acuminata have shorter wings(Table 1, and Cox 1987, Fig. 1), but cooped hasventral markings that resemble those ofacuminata (see above). Thus cooperi could bejudged to have characteristics intermediatebetween those of paramelanotos and acuminata.However, it is unlikely that cooped is a hybridparamelanotos x acuminata because bothspecimens of paramelanotos have characteristicsintermediate between those of jerruginea andmelanotos. In particular, whereas the specimensof paramelanotos seem to have some distinctlymarked scapulars, some of their other nuptialplumage scapulars show traces of the scapularpatterning of nuptially plumagedjerruginea (Fig.2 in Cox 1987). The split supercilium ofparamel­anotos is also discernible in photographs of adultmelanotos (Kaufman 1988) and of adult non-

DISCUSSION breeding plumagedjerruginea (Underhill 1987).Clearly, the closest relatives of cooped and Also, some upper tail-coverts of both specimens

paramelanotos are among the calidritine species of paramelanotos resemble those of nuptiallyfuscicollis, ferruginea, acuminata and melanotos. plumaged jerruginea and melanotos (Fig. 5).The principal questions are: are cooped and In pursuing the possibility of hybridization, itparamelanotos hybrids, or distinct but cryptic should be determined whether the putative paren­species, or constituents of a single species, tal species breed sympatrically and whether theirCalidris cooperi? mate recognition systems would allow hybridiza-

From the analysis in the previous section, the tion. The breeding grounds of ferruginea,most likely possibility is that they are hybrids. melanotos and acuminata overlap widely inHowever, on morphological considerations alone, northern Siberia, those of juscicollis andit is difficult to determine the species to which melanotos overlap in northern North Americathe interbreeding parents of a hypothetical hybrid (Marchant et al. 1986), and a small number ofbelong. Hybrids are sometimes greater in size and ferruginea have been found breeding in theweight than either parental species, and can even . Alaskan range of melanotos (Holmes & Pitelkapossess different plumage characters (Buckley 1964). Moreover, the males of fuscicollis,1982). It is possible that some birds that ferruginea, acuminata and melanotos, unlike the

MARCH,1989 179

males of other Calidris spp, take no part inincubation; fuscicollis, jerruginea and possiblyacuminata (which may be promiscuous likemelanotos)are polygynous, the males maintain­ing simultaneous pairbonds with more than onefemale; melanotos is promiscuous, the malesdisplaying towards any females entering theirterritory (Pitelka et at. 1974). If hybridizationbetweenjerruginea and melanotos is occurring,its chief locus could well be not Siberia, butAlaska, where the apparently low density ofjerruginea may be resulting in birds beingsometimes unable to find mates of their ownspecies (see Cox 1987). However, the habits ofthese birds indicate that observations of mixedmatings on the breeding grounds would be diffi­cult to obtain. The males and females do notnormally associate with each other after displayand copulation, and even if these actions areobserved their success is unlikely to be determin­able. Nevertheless, the potential for hybridizationclearly exists. Holmes & Pitelka (1964) sawindividuals of jerruginea with a group ofmelanotos in Alaska, and later found two nestsof jerruginea. They also discovered that somevocalizations and aspects of the display beha­viour of ferruginea are similar to those ofmelanotos, and stated that jerruginea "exhibitsa number of behavioural characters intermediate.between C. melanotos and more typical membersof Calidris. . ."

Dr. J. P. Myers (pers. comm., 3 November1988),having spent six years studying melanotosin the Arctic and in Argentina, wrote, "I have nodoubt about its potential involvement inhybridization. We have accumulated manyobservations of males of this species displayingat inappropriate subjects: dead male redphalaropes [Phalaropus julicarius] , dunlinchicks, adult dunlin - to mention a few."

It is possible that juscicollis occasionallyhybridizes with other species in this group.Through the courtesy of A. Palliser, I haveexamined colour slides of a Calidris photo­graphed by him at Tullakool Salt Works, NewSouth Wales. It had previously been identified asjuscicollis (Mitchell 1988), and in some respectsit closely resembles that species. However, itseems too large (in comparison with acuminataandjerrugineaalso in some photographs), its legstoo long, the bill too long with its base shapedlike that of jerruginea, and the wings too short.In addition, P. Maher, who also observed this

bird, informed me that it possessed a wing-barlike that of ruficollis. These characteristicssuggest that bird to have been a hybrid, or a runtof jerruginea. Another strange Calidris, seen atStrathroy, Ontario, 12-14 November 1980(Goodwin 1981), was said to resemble melanotosbut to have had black bill and legs. In thepublished photograph its bill and legs appearshort, but the wings extend well beyond the tail­tip. Possibly this was a hybrid juscicollis xmelanotosi,

Arguments have recently been presented insupport of the view that paramelanotos is adistinct species (Grant 1987,Kasprzyk et at. 1988,Buckley 1988). Kasprzyk et al. (1988) wrote,''Based on the increasing number of fieldsightings, the limited plumage variability betweenindividuals and the apparent scarcity of hybridcalidrids, Cox's Sandpiper may, in fact, representa valid species". Concerning the ''limited plumagevariability", however, it is possible that this resultsfrom only Fl hybrids being discernible in thefield; backcrosses would presumably tend to lookmore like the pure parent, thus escapingdetection. In fact, the specimens of cooperi andparamelanotos, together with the sightings ofunusual calidritines in Ontario and New SouthWales (see above), are, judging from their'differing external appearances, evidence that thecalidritine group of juscicollis, ferruginea,acuminata and melanotos sometimes producesdifferent kinds of hybrids. Moreover, and addingto the confusion, most Australian sightings ofbirds alleged to be paramelanotos are"undescribed (Cox 1987, 1989). Some, like theindividuals observed by Corben (see above), seemto have resembled cooperir. Others wereoriginally identified as alpina, and somepublished descriptions match that species ratherthan paramelanotos (Cox 1987).

CONCLUSIONSThe most likely solution to the problem of the

identities of cooperi and paramelanotos is thatthey are hybrids from parent species within thegroup of calidritines consisting of fuscicollis.,jerruginea, acuminataand melanotos. Studies oftheir external morphology render this theoryplausible, while the breeding sympatry andpolygynous or promiscuous mating systems ofthe species concerned make it feasible. It isimprobable that cooperi and paramelanotos aretwo distinct species. If they constitute one cryptic

180 SOUTH AUSTRALIAN ORNITHOLOGIST, 30

and largely overlooked species, Baird's (1858)name cooperi would have priority. Such a specieswould be sexually dimorphic and have differentnuptial and non-breeding plumages.

The hybrid theory requires proof from thecollecting of further individuals, together withadjunct (not alternative) biochemical andkaryotypic studies. Otherwise, in the absence ofobservations of mixed matings on the breedinggrounds, the identities of the putativeinterbreeding parents will remain hypothetical.

NarES

1. Everett & Prytherch (1987) reported a probable sightingof parame/anotos from Hong Kong on 17 April 1987.Buckley (1988) suggested it to be the first record ofparame/anotos away from its Australian winteringgrounds. The original observers, however, P. R. Kennerley,G. Speight et al., did not claim it as a positive record. Ihave read their field notes and believe them to refer mostlikely to a Ruff Philomachus pugnax, albeit a strangely­marked one; P. J. Grant (pers, comm. 13 June 1988)concurs.

2. Parker's original paper of 1982 was to have included adiscussion on the pros and cons of the hybrid case, adiscussion of Calidris cooperi, and colour plates of thevarious taxa. He informed me that the reasons for itsabbreviation will be treated in a forthcoming work.

3. Sharpe (1896: 565) regarded seven skins in the BritishMuseum (Natural History) from British Columbia asintermediate between C. acuminataand C. melanotos. S.A.Parker and I have examined these specimens and find themall unexceptional me/anotos.

4. The bird trapped at Stockton, New South Wales, andconsidered a hybridferruginea x acuminata (Lane et at.1981) also appears to resemble cooperi in certain respects.Unfortunately, details of its ventral markings were notpublished.

ACKNOWLEDGEMENTS

I am grateful to Shane Parker for his help in producingand writing this paper. I thank him for his assistance inlocating references, for his freely given help in providing thetime and trouble to answer many questions, and for aidingmy viewing of specimens held or borrowed by the SouthAustralian Museum. I thank Dr R. L. Zusi for forwardingthe colour slides of Calidris cooperi to the Museum, forallowing" their use in this article, and for his comments ona draft. I am also indebted to R. F. Brown and Leo Josephfor providing useful comments on earlier drafts of this paper,and for their assistance in many other ways. I thank C. R.Corben for providing his unpublished field notes on birds,and D. W. Eades for the use of the photograph of

parame/anotos.Dr Philippa Horton facilitated my examinationof specimens. I am grateful to Dr J. P. Myers for hisinformation about breeding behaviour of waders. Dr F. A.Pitelka generously supplied much information about hisextensive field work on sandpipers in Alaska. I am verygrateful to Dr Glen Ingram and Dr F. A. Pitelka for theircriticisms and comments on the manuscript.

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1. B. COX, 7 Agnes Court, Salisbury East,SA. 5109Received 16 August 1988; accepted 5 December1988