RARE OCCURRENCE FirstNorthern Hemisphere record and first juvenileplumage description of the Cox's Sandpiper(CMidris pammclanotos) Mark J. Kasprzyk, Richard A. Forster, idris paramelanotos)was observed and Brian A. Harrington AJUVENILEand photographedCOX'SSANDPIPER in Massachu-(CAL- settsSeptember 15-21, 1987. This spe- cies was first formally describedto sci- ence in 1982 (Parker 1982). Approxi- mately 40 individualshave been seenin the field with only two specimensknown to exist, both of which are adults. All previous records have been from Aus- tralia. Becauseof the infrequencywith which Cox's Sandpiper has been re- ported and the fact that its breeding groundsare unknown, it is possiblethat this form may be a hybrid (Marchant et al. 1986) rather than a valid species. While mist-netting shorebirds the night of September15, 1987, staffof the Manomet Bird Observatory caught what initially appearedto be a Pectoral Sandpiper(Calidris melanotos)at Dux- bury Beach, Plymouth County, Mas- sachusetts.During banding,we noticed that someof the morphologicalfeatures of the sandpiperwere strange:the bill was very long and the breast streaking was not as prominent or sharply de- marcatedas in a PectoralSandpiper, es- pecially where the streaking faded out along the lower median edge of the breast. The bird was aged as a juvenile on the basisof its fresh plumage, par- ticulafiy its unworn tertials. The indi- vidual was banded, measured, photo- graphed, and released during the early morning of September 16. The especiallylong black bill with slightlydrooping tip wasthe mostobvious field characteristic In later reference to literature con- of the Coxg SandpiperDuxbury Beach, Massachusetts, September 16, 1987. Photo/MarkK. cerning Pectoral Sandpiper plumages, Kaspryzk. Volume 41, Number 5 1359 suchas the long black bill and leg color better fit the description for Cox's Sandpiper. On September19, after further study of the bird at Duxbury Beach,and based on the field characters and measure- mentswe had discussed,Forster became convinced that the bird was a Cox's Sandpiper. On September 19 and 20, several more observersexperienced in shorebird identification studied the bird with us. The extensive white sides of the rump, uncharacteristic of Sharp- tailed Sandpiper, were well-seenwhile the bird preened; the extensive white uppertail coverts contained a few streaksthat ran parallel along the dark central tail band, unlike the unmarked uppertailcoverts of PectoralSandpiper. The uniform ageof the body feathering and the light edgings of most dorsal body feathering characterizedthe bird asa juvenile. We ultimately agreedthat the long, entirely black bill, the pro- portionatelylong olive legsand the ex- tensively white uppertail coverts with light streaking most closely matched those characters describing a Cox's Note thefine breaststreaking against the buffybackground. Streaking is bolderon the sides Sandpiper. of theupper breast and absent Jkom the roedial portion of thelower breast. Buffy background On Monday. September 21, staff at colorationof the breastis not sharplydelimited from the white of the belly.Note the split Manomet Bird Observatorymet to dis- supercilium,with the upperbranches less prominent than the lower.Duxbury Beach, Massa- cuss how to proceed with the Cox's chusetts,September 16, 1987. Photo/Mark Kaspryzk_ Sandpiper.Scientifically, a strongcase we found many important contraststo the fine streaks faded near the lower existedfor collectingthe bird. Not only the characters we had seen. Adult Pec- central edge of the breast, unlike the did this individual representwhat was torals are boldly patterned on the chest, stronglypatterned, sharplydemarcated apparently the first known example of and juveniles, although less promi- streakingof a Pectoral Sandpiper. By a juvenile Cox's Sandpiper and a first nently marked than adults, still possess default, the bird was then identified as record for the northern hemisphere,but a complete, well demarcated pectoral an adult Sharp-tailed Sandpiper that a preserved specimen would provide band. Therefore, we consideredSharp- possesseda plumage unfamiliar to us. various characters that could be used to tailed Sandpiper (C. acuminata) to be We were confidentthat it was not a ju- study the bird's taxonomic status. the most likely alternative identifica- venile of this species.The Massachusetts However, another option was to usethe tion, althoughthe bird possessedexten- Audubon Society rare bird alert was techniqueofmitochondrial DNA anal- sive streakingon the upper breast and notified of the bird with its new iden- ysis based on blood samples to deter- lacked the orangishcolor on the upper tification that afternoon. mine the relationship of Cox's Sand- breast and crown characteristicof ju- Later that night, we discussedour piper to other species.Such a blood venile C. acuminata. misgivingsabout the bird's identifica- sampleis best obtained from a live bircL Remaining unconvinced, Kasprzyk tion as an adult Sharp-tailedSandpiper This procedurealso alleviated our con- returned to Duxbury Beach on the eve- and consideredthe possibilityof a Cox's cern about collectingwhat might be an ning of September 17 and recorded a Sandpiper (Calidris paramelanotos). exceptionally rare specieswhose distri- complete field description of the bird. Comparison of the in-hand measure- bution and total population size are On September 18 it was studied by ments were made against measure- unknown. We therefore decided to at- many observers,including the authors, ments for Sharp-tailed, Pectoral and tempt to recapture the bird. as it foragedin the wrack with Short- Cox's sandpipersgiven lzy Marchant et Rocket-nets were set up at the high billed Dowitchers(Limnodromus gris- al. (1986). The bill length was well tide line of Duxbury BeachSeptember eus), White-rumped Sandpipers (C. within the appropriaterange for Cox's 21--23 in an effort to recapture the fuscicollis)and SemipalmatedSandpi- Sandpiper;further, it was 3 millimeters bird. However, we did not see the bird pers (C. pusilia). The bill was long, longer than the maximum bill length after the morning of September21. Af- rather fine, and decurved; the upper listed for Pectoral Sandpipers, and 7 ter September 21, a noticeable reduc- chest and breast were finely streaked; millimeters longer than that given for tion in shorebirdnumbers and diversity, and the legswere olive, darker than the Sharp-tailed Sandpipers(Marchant et followinga break in the persistentstorm typical yellowish of a Pectoral Sandpi- al. 1986). As we compared the field pattern, indicated that many birds had per. All observerscommented on how marks, we discovered that characters resumedmigration. 1360 American Birds, Winter 1987 Descriptionof a juvenile Cox's Sandpiper Measurements taken of the bird in hand are followed by measurementsin parenthesesfrom Marchant et al. (1986) based on two specimensand one live bird, and from Lane et aL (1981) for weightbased on one bird. Note that the wing measurementslisted in Marchant et al. are basedon a flattened wing. wing (unflattened)chord: 129 mm (I 34- 144 mm) culmen(exposed): 35. I mm (33-37 mm) weight: 67.9 g (67 g) Bill: In the field,appears entirely black: in hand, the base of the lower mandible and the upper mandible immediately anterior to nares is slightlypaler with a grayish-olivetone. Long and thin, slightlydecurved at the tip, slightly longerthan the lengthof the head.Longer and proportionatelyfiner than on eitherSharp-tailed or Pectoralsandpipers; slightly shorter and not as "thick," especiallybasally, as in Dunlin (C. alpina). Most similar to Curlew Sandpiper(C. ferruginea),but lessstrongly decurved, and with a lesspointed tip. Legs: Olive or olive-brown. Proportionately longer-leggedappearance in comparisonwith PectoralSandpiper. Leg color darker than the yellowishleg coloration of PectoralSandpiper, mostclosely resembling that of Stilt Sandpiper Here the breastcoloration and streakingare evident,as is the bird• elongatedbill. Duxbury, (C. himantopus). Beach,Massachusetts, September 16, 1987. Photo/Mark K Kaspryzk. Breast:Incomplete band of fine blackish-brown supercilium faded out, and the conspicuous Tail: A detaileddescription of the rectriceswas streaksrunning vertically acrossa rich buff lower branch extendedslightly upwards, con- not obtained.Photographs of the bird in-hand background,the streaksbeing lighter, finer and tributing to a slightlycapped appearance. indicatesthat the tail wasuniformly dark. Cen- lessclearly demarcatedthan in PectoralSand- tral rectriceswere longer and more pointedthan Wing: Upper wing coverts were light gray- piper. Streaksbecoming less pronounced to- outer feathers,similar to a PectoralSandpiper. ward the lower central region of the breast, brownedged pale buff, lower wing coverts edged which appearsunstreaked in the field; in the rufons.Primaries dark blackish-brown.In flight, Behavior hand,small blackish-brown flecks were present narrow white wing bar formed by pale tips of in this region.Breast patterning lacks the sharp greater secondarycoverts. At rest, primaries cutoff characteristic of Pectoral Sandpiper. extendedjust beyondthe tail. Tertialswere dark The bird foraged in the wrack by blackish-brownbroadly edgedwith bright ru- Streakingextends farther along the upperflanks peckingand probing. While the Cox's than in Pectoral Sandpiper. Breast coloration fous. Sandpiperwas alwaysseen in the com- and patternsomewhat reminiscent of juvenile Scapulars: Lower scapulars with blackish- Baird'sSandpiper (C.