Dunlin subspecies exhibit regional segregation and high site fidelity along the East Asian–Australasian Flyway

Abstract

The degree to which individuals migrate among particular breeding, migration, and wintering sites can have important implications for prioritizing conservation efforts. Four subspecies of Dunlin (Calidris alpina) migrate along the East Asian−Australasian Flyway. Each subspecies has a distinct and well-defined breeding range, but their migration and winter ranges are poorly defined or unknown. We assessed the migratory connectivity of 3 of these subspecies by evaluating a dataset that encompasses 57 yr (1960–2017), and comprises more than 28,000 Dunlin banding records and 818 observations (71 recaptures and 747 band resightings). We present some of the first evidence that subspecific segregation likely occurs, with arcticola Dunlin wintering in areas of Japan, and other arcticola, actites, and sakhalina Dunlin wintering in areas of the Yellow and China seas. Observations indicate that whether an arcticola Dunlin winters in Japan or the Yellow and China seas is independent of their breeding location, sex, or age. Furthermore, observations indicate that ≥83% of arcticola Dunlin exhibit interannual site fidelity to specific wintering sites. This suggests that the degradation of specific wetland areas may negatively affect particular individuals of a particular subspecies (or combination of subspecies), and, if widespread, could result in population declines. Given the possible biases inherent in analyzing band recovery data, we recommend additional flyway-wide collaboration and the use of lightweight tracking devices and morphological and genetic assignment techniques to better quantify subspecies’ migratory movements and nonbreeding distributions. This information, when combined, will enable effective conservation efforts for this species across the East Asian−Australasian Flyway.

Migratory network reveals unique spatial-temporal migration dynamics of Dunlin subspecies along the East Asian-Australasian Flyway

“…The authors also found that continued habitat degradation at key sites in the Yellow Sea would likely have a strong negative effect on all 4 Dunlin subspecies, because 21-50% of subspecific migration recoveries were connected to the region. Although these findings are a useful step toward understanding Dunlin migration dynamics on the EAAF, Lagasse ´et al [40] failed to locate any recoveries of the kistchinski subspecies and warned of the likely effects of regionally biased observer effort on regional recovery patterns. The authors were also unable to determine how birds moved between initial capture sites and recovery sites, and consequently, lacked information on the spatial and temporal migration dynamics of the 4 subspecies.…”

“…By compiling band recoveries, Lagasse ´et al [40] provided the first detailed information on the migration patterns of the 4 Dunlin subspecies that migrate and winter along the EAAF (C. a. actites, arcticola, kistchinski, and sakhalina). In their analysis, the authors found that Dunlin in Japan are predominantly C. a. arcticola, while Dunlin migrating and wintering in other areas of the EAAF may comprise all 4 subspecies.…”

“…South migration ended, and the winter period began, when an individual arrived at a stationary estimate that was south of 45.5˚N and that lasted for � 42 days. We chose 45.5˚N and � 42 days as the migration-winter threshold because Dunlin on the EAAF overwinter at latitudes this far north [40], are generally stationary through the winter [58,70,71], and typically stop at migration sites for < 42 days [58,70,73]. The winter period ended, and north migration began, when an individual departed for a stationary estimate north of 45.5˚N (i.e., outside of the typical wintering range), or to a stationary estimate(s) south of 45.5˚N and for < 42 days before migrating north of 45.5˚N.…”

Warming Arctic summers unlikely to increase productivity of shorebirds through renesting

“…Study species. The arcticola Dunlin breeds in northern Alaska (and rarely in northwestern Canada) and winters in Asia, along the coasts of China, Japan, Taiwan, North Korea, and South Korea 77,78 . This subspecies is thought to be declining 34,79 , with recent evidence suggesting the loss of non-breeding habitat [39][40][41][42] is causing low annual adult survival 38 .…”

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).…”