Intra- and interannual regional fidelity of Semipalmated Sandpipers (Calidris pusilla) during migratory stopover in the upper Bay of Fundy, Canada

Abstract

The Bay of Fundy, Canada is a critical migratory stopover for Semipalmated Sandpipers (Calidris pusilla) during fall migration. Recent ecological changes combined with range-wide population declines indicate that a re-evaluation of habitat use and regional fidelity is required. The Bay of Fundy is divided into three regions, each of which contains multiple foraging and roost sites. In this study, we examined local movement and regional fidelity within and between years using radio-telemetry and field-readable markers. We deployed 194 radio-transmitters and 2295 field-readable flags on Semipalmated Sandpipers during migration in 2013-2014, and resighted these birds, along with additional birds flagged in 2012, between 2013 and 2016. Radio-tracked birds used on average 1.3 to 4.1 foraging and roost sites per day, with most making multiple daily movements, but only 2% made permanent moves between geographically distant regions within the bay during stopover. Additionally, 97% of birds returned to their original region in subsequent years. The use of multiple sites suggests Semipalmated Sandpipers are capable of adapting to dynamic conditions in the Bay of Fundy on a local scale, but the high regional fidelity suggests that their ability to adapt to changes occurring at a regional scale may be limited. Uncertainty about the capability of Semipalmated Sandpipers to flexibly move among different regions of the Bay of Fundy supports the need for conservation at both the site and regional level. Fidélité régionale intra-et interannuelle des Bécasseaux semipalmés (Calidris pusilla) aux haltes migratoires dans le fond de la baie de Fundy, Canada RÉSUMÉ. La baie de Fundy, au Canada, représente une halte essentielle pour les Bécasseaux semipalmés (Calidris pusilla) durant la migration automnale. Une réévaluation de l'utilisation de l'habitat et de la fidélité régionale est nécessaire en raison de changements écologiques récents couplés aux diminutions de population à grande échelle. La baie de Fundy se divise en trois régions, chacune comptant de nombreux sites d'alimentation et de repos. Nous avons examiné les déplacements locaux et la fidélité régionale des bécasseaux au cours d'une même année et entre les années, au moyen de la radiotélémétrie et de marqueurs lisibles à distance sur le terrain. Nous avons posé 194 émetteurs radio et 2 295 marqueurs sur des Bécasseaux semipalmés durant les migrations de 2013 et 2014, et avons réobservé ces oiseaux de 2013 à 2016, en plus d'autres oiseaux munis de marqueurs en 2012. Les oiseaux suivis par radio ont utilisé de 1,3 à 4,1 sites d'alimentation et de repos en moyenne par jour, la plupart se déplaçant plusieurs fois quotidiennement, tandis que 2 % seulement se sont déplacés de façon permanente entre des régions distantes dans la baie en cours de halte. De plus, 97 % des oiseaux sont retournés dans leur région d'origine dans les années subséquentes. Le fait que les Bécasseaux semipalmés utilisent de multiples sites donne à penser qu'ils sont capables de s'adapter aux conditions dy...

Are disproportionate losses of eastern breeding Semipalmated Sandpipers (Calidris pusilla) driving declines in the upper Bay of Fundy, Canada?

“…We have observed a shift in the timing of southbound fall migration of Semipalmated Sandpipers in the Bay of Fundy. The median passage date is now 4.5-5 d later than it was in the 1980s, and aerial surveys clearly point to a decline in migrants early in the season and a later peak in bird abundance (Neima 2017).…”

“…Populations of Semipalmated Sandpipers have declined in recent decades. Multiple independent analyses have detected declines from the 1970s to 1990s for eastern populations on both the breeding grounds (Hitchcock andGratto-Trevor 1997, Jehl 2007) and at fall migration staging sites (Morrison et al 1994, Aubry and Cotter 2001, Ross et al 2001, Neima 2017. Large declines in populations wintering in northern South America have also been reported (Morrison et al 2012).…”

“…comm.). Within the Bay of Fundy, aerial survey data suggest steep declines until the early to mid-2000s, after which declines stopped; current populations appear to be approximately half of the historical level (Neima 2017). There is less evidence of changes in central Arctic populations (Smith et al 2012) but population trend data in that region are sparse (Gratto-Trevor et al 2012b).…”

Detection range of songbirds using a stopover site by automated radio‐telemetry

“…The Motus Wildlife Tracking System (hereafter, Motus; Taylor et al 2017), an international collaborative network of automated radio-telemetry arrays, has proved useful for estimating many movement behavior parameters, including onset of diel activity (Crysler et al 2016), precise arrival and departure times at stopover sites (Mitchell et al 2015, Dossman et al 2016, M€ uller et al 2016, and determining factors that influence the duration of migratory stopovers (Dossman et al 2016, Mann et al 2017, Neima 2017. However, little has been done to quantify the performance of the Motus system, including the effective detection range of receiving antennas, and whether and how detection probability varies with habitat type, species, or other factors.…”

“…, Mann et al. , Neima ). However, little has been done to quantify the performance of the Motus system, including the effective detection range of receiving antennas, and whether and how detection probability varies with habitat type, species, or other factors.…”