Data from: Consistent declines in wing lengths of Calidridine sandpipers suggest a rapid morphometric response to environmental change

A recent study demonstrated that semipalmated sandpiper (Calidris pusilla)
wing lengths have shortened from the 1980s to the present-day. We examined
alternative and untested hypotheses for this change at an important
stopover site, James Bay, Ontario, Canada. We evaluated morphometric
patterns in wing length and bill length by age and sex, when possible, and
assessed if wing shape has also changed during this time-period. We
investigated patterns of morphological change in two additional
Calidridine sandpipers, white-rumped sandpipers (Calidris fuscicollis) and
least sandpipers (Calidris minutilla), to determine if shorter wing
lengths are a widespread pattern in small sandpipers. We also examined
allometric changes in wing and bill lengths to clarify if wing length
declines were consistent with historical scaling relationships and
indicative of a change in body size instead of only wing length change. We
found that including sex and wing shape in analyses revealed important
patterns in morphometric change for semipalmated sandpipers. Wing lengths
declined for both sexes, but the magnitude of decline was smaller and not
significant for males. Additionally, semipalmated sandpiper wings have
become more convex, a shape that increases maneuverability in flight. Wing
lengths, but not bill lengths, declined for most species and age classes,
a pattern that was inconsistent with historical allometric scaling
relationships. For juvenile semipalmated sandpipers, however, both bill
and wing lengths declined according to historical scaling relationships,
which could be a consequence of nutritional stress during development or a
shift in the proportion of birds from smaller-sized, western breeding
populations. Except for juvenile semipalmated sandpipers, we did not find
evidence for an increase in the proportion of birds from different
breeding populations at the stopover site. Given the wide, hemispheric
distribution of these sandpipers throughout their annual cycles, our
results, paired with those from a previous study, provide evidence for
wide-spread reduction in wing lengths of Calidridine sandpipers since the
1980s. The shorter wing lengths and more convex wing shapes found in this
study support the hypothesis that selection has favored more maneuverable
wing morphology in small sandpipers.