Evidence of differing staging strategies between adult and juvenile Semipalmated Sandpipers highlights the importance of small staging sites in Atlantic Canada

Abstract

Abstract Semipalmated Sandpipers (Calidris pusilla) are Arctic-breeding shorebirds that use staging sites in Atlantic Canada during their southbound migration to South America. The upper Bay of Fundy is recognized as a critical staging area, but hundreds of smaller sites outside the Bay of Fundy also host staging Semipalmated Sandpipers and have received comparatively little attention. Using the Motus Wildlife Tracking System, we tracked adult and juvenile Semipalmated Sandpipers and identified different staging strategies used by sandpipers tagged inside and outside the Bay of Fundy. Birds tagged in the Bay of Fundy remained there, while birds tagged along the Northumberland Strait, a tidal water body along the eastern coast of New Brunswick and northern Nova Scotia displayed multiple strategies. Most birds tagged along the Northumberland Strait used sites outside the Bay of Fundy exclusively, while a smaller proportion moved to the Bay of Fundy. Length of stay was shorter for birds using only sites outside the Bay of Fundy compared to birds using Bay sites or transferring between them. Choice of departure conditions also varied; birds using the Bay were more selective of specific wind conditions, favoring north and northwesterly winds. We found juvenile Semipalmated Sandpipers stayed 3 days longer in the region than adults and appeared to use a broader variety of sites. Our results highlight the importance of implementing conservation measures for smaller, lesser-known staging sites in Atlantic Canada, many of which are at an increased risk of loss and degradation due to climate change, coastal development, pollution, and human disturbance.