Friday, April 27, 2018


Spring (green) and fall (red) locations for museum specimens of the Eskimo Curlew.

With examination of the specimen holdings at the U.S. National Museum and Yale Peabody Museum, our investigations into the external features of the Eskimo Curlew are drawing to a close.  To date, we have examined 86 specimens that were collected in spring, summer, fall and winter.  On each, we have made a series of measurements and also taken photographs of  breast, wing and back plumage. 

To examine differences in measurements, we used a statistical technique called discriminant function analysis.  This technique allows us to examine all measurements simultaneously.  Doing so has permitted us to conclude that males significantly differ from females in particularly bill and tail length.  We found no seasonal differences in measurements, however.  We are still working on comparing measurements of adults and juveniles.

To determine identity of adults and juveniles, we are scoring each specimen for a number of plumage traits, including shape, color, size and density of breast markings, feather edging of wing coverts and extent of spotting on back and scapular feathers.  Although this investigation is still ongoing, it so far appears that traditionally used means of aging individuals do not hold up to careful scrutiny.

In addition to examining specimens themselves, we are also studying the location data attached to each individual.  As traditionally thought, fall migration occurs principally through the Northeast, whereas spring migration occurs through the Great Plains.  Five late May specimens from Alaska provide evidence for a previously unconfirmed breeding population there, whereas specimens from western New York and Montreal provide evidence for a hypothesized fall migration corridor through the northeastern United States.

No comments:

Post a Comment