Trends in abundance of Semipalmated Sandpipers: evidence from the Arctic.

摘要

Counts of Semipalmated Sandpiper (Calidris pusilla) at some migratory stopover sites have shown pronounced declines over the last 35 years. Counts from breeding grounds avoid sources of bias that have proven troublesome for trends estimated from migration surveys. Published and unpublished data were reviewed to examine trends in densities of Semipalmated Sandpipers at breeding sites across Alaska and arctic Canada. Information was sparse, and some comparisons are tenuous because methods varied over time. Valid time series were obtained for 13 sites across the species' range. In Alaska, Semipalmated Sandpipers either increased or were at least stable at six sites and decreased at one site. Surveys at both sites in the central portion of the range suggested no change in abundance. In the eastern portion of the range, trends were variable: decreases were observed at two sites, a possible increase at one site, and no change at another. Thus, the species was generally increasing or stable in the western and central portions of the range and had an uncertain status in the east. Also, trends in presence/absence data were analyzed from the Northwest Territories and Nunavut Checklist Survey. The species was observed at 345 sites, and results suggested that birds increased significantly in prevalence (assumed here to be correlated with abundance) across arctic Canada between 1987 and 2007. Overall, data from the breeding grounds do not support a range-wide decline in the abundance of Semipalmated Sandpipers, although data are insufficient for the long-billed population from the eastern Arctic for which specific conservation concerns exist.Digital Object Identifier http://dx.doi.org/10.1675/063.035.0111