Semipalmated and Least Sandpipers (Calidrispusilla, C. minutilla) were captured in Delaware Bay, USA, from 1995–1997 and from 2000–2008 to investigate changes in energetic condition during northbound migration staging. For Semipalmated Sandpiper, a model containing the effects of Julian day, period (Early: 1995–1997, Middle: 2000–2004, Late: 2004–2008) and habitat type (marsh, beach), as well as all interaction terms for these variables (the “full” model) had the strongest support (i.e. lowest AIC score) compared to six reduced models. Results suggested that mean size-adjusted mass declined significantly across periods (Early > Middle > Late). Also, rate of increase in size-adjusted mass within staging periods was significantly greater during the Early compared to Middle and Late periods. For Least Sandpiper, a reduced model that included Julian day and Period had the strongest support. Size-adjusted mass was significantly lower in the Late compared to Early and Middle periods, which were not different from each other. While in Delaware Bay, Semipalmated Sandpipers feed primarily on horseshoe crab eggs during episodes of rapid mass accumulation, but harvest pressure from 1995–2005 dramatically reduced egg availability. Least Sandpipers appear less dependent on this resource, which may explain differences between the two species regarding changes in energetic condition during staging periods in Delaware Bay. Long-term population trend indices suggest that Semipalmated Sandpiper has declined significantly since the 1980s, especially populations migrating along the Atlantic Coast en route to eastern Canadian breeding areas, which could be related, in part, to changes in food availability in Delaware Bay.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 35 • No. 1