Comprehensive estimation of spatial and temporal migratory connectivity across the annual cycle to direct conservation efforts

Abstract

Research666 the probability that our method missed peaks (spatial: 0.12, temporal: 0.18) or detected false peaks (spatial: 0.11, temporal: 0.37) due to data gaps and showed that our approach remains useful even for sparse and/or sporadic location data. Our study presents a generalizable approach to evaluating migratory connectivity across the full annual cycle that can be used to focus migratory bird conservation towards places and times of the annual cycle where populations are more likely to be limited.

High spatiotemporal overlap in the non‐breeding season despite geographically dispersed breeding locations in the eastern whip‐poor‐will (Antrostomus vociferus)

“…the average distance between an individual and all other individuals outside of its breeding population on a given date in migration) and date (similar to Ng et al, 2018). We refer to this analysis as “spatiotemporal overlap,” as it explicitly measures the overlap of distinct breeding populations in time and space, and thus can be used to identify spatiotemporal bottlenecks throughout migration (sensu Cardenas‐Ortiz et al, 2020; Knight et al, 2021). To test how spatiotemporal overlap changes throughout migration, we fit a linear mixed‐effects model with the response variable interindividual distance, and fixed effects of date, date 2 , date 3 , breeding latitude, plus the interactions between all polynomials of date and breeding latitude.…”

“…r M is still the most prevalent approach for quantifying connectivity throughout migration (e.g. Knight et al, 2021;Norevik et al, 2020; but also see Cohen et al, 2018Cohen et al, , 2019Knight et al, 2018). The main advantage of r M is that it is standardized (i.e.…”

“…breedingwinter migratory connectivity (BWMC); Webster & Marra, 2005) and throughout migration (i.e. en route migratory connectivity (ERMC); Cohen et al, 2018Cohen et al, , 2019Knight et al, 2021). Both types of connectivity are critical for a full annual cycle approach to conservation planning (Cohen et al, 2018;Faaborg et al, 2010;Webster et al, 2002).…”

“…On the contrary, species migrating with no spatial overlap (e.g. on opposing sides of a migratory divide; Delmore & Irwin, 2014) will have high ERMC regardless of phenology (see figure 1 in Knight et al, 2021 for a visualization of the spatiotemporal aspects of ERMC). Furthermore, migratory route can influence population mixing during winter (Finch et al, 2017).…”

Differential population trends align with migratory connectivity in an endangered shorebird

“…Migratory connectivity is understood for a growing number of species (Brown et al, 2017; Finch, Butler, Franco, & Cresswell, 2017; Knight et al, 2018, 2021; Lagassé et al, 2020; Trierweiler et al, 2014), which in turn is leading to an increase in empirical evidence of links between connectivity and population dynamics (Hewson, Thorup, Pearce‐Higgins, & Atkinson, 2016; Kramer et al, 2018; Rushing, Ryder, & Marra, 2016). In a study of two migratory songbirds with partially overlapping breeding grounds in North America, breeding populations of both species that overwintered in Central America were stable, whereas populations of one species that overwintered in northern South America, where deforestation was greater, underwent steep declines (Kramer et al, 2018).…”