1990-2 - Dutch Birding

The enigmatic Cooper's and Cox's Sandpipers
rABLE 1 Measurements (mm) of Calidris cooperi and C parameranotos and trapped simila r
bird s
wing tail tarsus culmen reference
C cooperi (specimen )
USNM 5989 145,7 55 29 .9 31 .1 R L Zusi (in litt )
C paramelanotos (specimens )
SAM B28843 134 - 30 .1 32 .5 Parker (1982 )
SAM B30775 144 57 .3 31 .5 37 .3 Parker (1982 )
similar líve birds
Australia 137 54 - 34 .5 Lane et al i- 981 )
USA - - - 35 .1 Kasprzyk et al (1988)
exhibit dark-brown wedge-shaped streaks . As feather growth continues the paler tips
and fringes abrade while the dark central markings flare outwards, flrstly on the
flanks. to eventually become bars and chevrons that coverthe underparts except the
white belly. The ventral markings of C cooperi are typical of C acumirtata in an
intermediate stage of feather growth .
C cooperi has the primary-shafts white post-medially, grading into greyish-brown
basally and terminally (Ridgway 1919) . In this coloration and in the buff edges to the
tertials . it is identical to C acuminata (Cox 1989a) .
The rump-feathers of C cooperiand Cparamelanotosare similar in coloration but the
patterning on their uppertaii-coverts differs subtlely but significantly (Cox 1989a) . In
both C paramelanotos, the lateral uppertail-coverts are white, with the most posterior
ones marked with a blackish V-shaped central marking across both webs ., as in C
melanotos. They also have some central uppertail-coverts whitish and marked with
blackish bars basally and subterminally, as in C ferrLgirrea. Ccooperr, however, has
all of its white lateral uppertail-coverts marked by a thin blackish line along the shaft
from which a thicker diagonal bar tapers outwards to near the edge of each teather .
These markings are identical to those of C acurrrinata and are only super`icially Vshaped
and not the same as in C canutus as was believed by Baird (1858) . The type
of C coaperihas some uppertail-coverts missing but the most central ones are white .
crossed by a broad blackish bar that extends along the shaft into a polnt .
It has been stated that C cooperidiffers from C paramelanotos by having a straight
bill, as opposed to a slightly decurved one (Kasprzyk et al 1988 . McAllan & Bruce
1989) . but on the dried skin the upper mandible is unnaturaNy bent upwards while the
lower is slightly decurved . Presumably. post mortem changes caused this eistortion .
In life, C cooperiprobably has a slightly decurved bill like C paramelarrotos and other
sandpipers (Cox 1989a) .
The subtle difference in bill width between C cooperi and C paramelanotos is of
doubtful significance . The bil{ of C cooperi is slightly broader and shorter than that
of C parametanotos . and slightly longer and narrower than in C melanotos (Cox
1989a ) .
measurements
Baird's (1958) measurerrlents of C cooperisuggested to McAllan & Bruce (1989) that
it was appreciably greater in total length than both specimens of C paramelarrotos .
Neverthe#ess, the total length measurement of a bird cannot be assessed once it i s
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