Length of stay and departure strategies of Semipalmated Sandpipers (Calidris pusilla) during post-breeding migration in the upper Bay of Fundy, Canada

Abstract

The Bay of Fundy, Canada is a critical staging area for Semipalmated Sandpipers (Calidris pusilla) during post-breeding migration. Recent range-wide population declines and changes in diet and migratory timing in the Bay of Fundy prompted a re-examination of staging ecology, including length of stay (last estimated in 1981), which is used in calculating migratory population estimates. We used radio-telemetry and the Motus Wildlife Tracking System to estimate individual length of stay and departure conditions for 159 Semipalmated Sandpipers in 2013 and 2014. Using tracking data we compared two estimation methods, minimum length of stay and mark-recapture modelling. Using minimum length of stay, the mean length of stay was approximately 21 days, an increase from the previous estimate of 15 days. Mark-recapture models suggested a much longer staging period that is inconsistent with other data. Sandpipers captured early in the staging period stayed longer on average than those captured later. Departures from the staging area were correlated with north-westerly winds, moderate to high wind speeds and low but rising atmospheric pressures. We suggest that Semipalmated Sandpipers in the Bay of Fundy are not operating on a time-selected migration schedule and instead wait for favourable weather conditions to depart, which occur more often later in the migratory period. Population trends in the Bay of Fundy should be re-evaluated in light of the increased length of stay.

Accelerating declines of North America’s shorebirds signal the need for urgent conservation action

“…However, the small amount of evidence available at present does not support this hypothesis. Radio-telemetry studies in the Bay of Fundy showed that stopover duration of Semipalmated Sandpipers has not decreased, but rather increased from ∼2 weeks in the 1980s to 3 weeks in the 2010s, during which time passage population estimates have declined by 50% (Neima 2017). Additional work is needed to estimate current lengths of stay at key stopover sites, for example using available MOTUS telemetry (Taylor et al 2017) data or other tracking technologies, and to compare these values to the fragmentary historical data.…”

Variation in resource use between adult and juvenile Semipalmated Sandpipers (Calidris pusilla) and use of physiological indicators for movement decisions highlights the importance of small staging sites during southbound migration in Atlantic Canada

“…Sandpipers tagged within the Bay of Fundy remained within the Bay, while those tagged at Petit Cap either remained outside the Bay or moved into the Bay and remained there for the duration of their staging period in Atlantic Canada (see Linhart et al, in press for details). We calculated a minimum length of stay (as in Neima et al, 2022) for each bird by subtracting the deployment timestamp from the last known detection in Atlantic Canada. Detailed analyses of movement strategies, length of stay, and differences in site use between ages and tagging locations can be found in Linhart et al (in press).…”

“…Recent work has found adult sandpipers using the Bay of Fundy have high within and between-year fidelity, returning to the same areas of the Bay each year (Neima et al, 2020). Additionally, the behavior, movement and diet of adult sandpipers in this habitat are well understood (e.g., MacDonald et al, 2012;Quinn and Hamilton, 2012;Neima et al, 2022). Less is known about the use of these habitats by juvenile Semipalmated Sandpipers, which may need additional time or resources to gain sufficient weight for a successful southbound migration.…”

Environmental factors influencing red knot (Calidris canutus islandica) departure times of relocation flights within the non‐breeding period

“…Many studies have demonstrated the importance of departure timing of long migratory flights (Alerstam, 2009; Anderson et al., 2019; Bradarić et al., 2020; Leyrer et al., 2009; Manola et al., 2020; Neima et al., 2022; Newton, 2007; Packmor et al., 2020; Piersma & Jukema, 1990; Sapir et al., 2011; Tulp et al., 1994; Woodworth et al., 2015), but non‐migratory flights, whereby birds may relocate within the overwintering range, have received little attention, even though distances traversed can extend dozens of kilometers (Frederiksen et al., 2012; Swindells, 2019) and can involve risky barriers. Given the potential rise in extreme weather events due to climate change, it becomes crucial to comprehend the specific conditions that birds prefer during departure, even for flights within their overwintering range.…”