Hidden in plain sight: migration routes of the elusive Anadyr bar‐tailed godwit revealed by satellite tracking

Abstract

Satellite and GPS tracking technology continues to reveal new migration patterns of birds which enables comparative studies of migration strategies and distributional information useful in conservation. Bar-tailed godwits in the East Asian-Australasian Flyway Limosa lapponica baueri and L. l. menzbieri are known for their long nonstop flights, however these populations are in steep decline. A third subspecies in this flyway, L. l. anadyrensis, breeds in the Anadyr River basin, Chukotka, Russia, and is morphologically distinct from menzbieri and baueri based on comparison of museum specimens collected from breeding areas. However, the non-breeding distribution, migration route and population size of anadyrensis are entirely unknown. Among 24 female bar-tailed godwits tracked in 2015-2018 from northwest Australia, the main non-breeding area for menzbieri, two birds migrated further east than the rest to breed in the Anadyr River basin, i.e. they belonged to the anadyrensis subspecies. During pre-breeding migration, all birds staged in the Yellow Sea and then flew to the breeding grounds in the eastern Russian Arctic. After breeding, these two birds migrated southwestward to stage in Russia on the Kamchatka Peninsula and on Sakhalin Island en route to the Yellow Sea. This contrasts with the other 22 tracked godwits that followed the previously described route of menzbieri, i.e. they all migrated northwards to stage in the New Siberian Islands before turning south towards the Yellow Sea, and onwards to northwest Australia. Since the Kamchatka Peninsula was not used by any of the tracked menzbieri birds, the 4500 godwits counted in the Khairusova-Belogolovaya estuary in western Kamchatka may well be anadyrensis. Comparing migration patterns across the three bar-tailed godwits subspecies, the migration strategy of anadyrensis lies between that of menzbieri and baueri. Future investigations combining migration tracks with genomic data could reveal how differences in migration routines are evolved and maintained.

The effects of cities on quail (Coturnix coturnix) migration: a disturbing story of population connectivity, health, and ecography

“…A migratory network could help to explain the migratory divide of barn swallows ( Hirundo rustica ) in America (Turbek et al 2022 ) and China (Hobson et al 2015 ) as well as Swainson’s thrushes ( Catharus ustulatus ) in America (Justen et al 2021 ). This plasticity in the chosen route is a response to environmental conditions (Verhoeven et al 2022 ) that could reveal different migration strategies in different subspecies (Chan et al 2022 ). Stored energy reserves and tailwinds influence route selection (Purcell and Brodin 2007 ), but the route chosen may influence a species’ population dynamics (Cohen et al 2017 ).…”

Phylogeography of bar-tailed godwits: pre-LGM structure in Beringia and westward colonization of post-glacial Europe

“…We were unable to completely resolve structure among the three Beringian subspecies due to the small number and high sequencing failure rate of purported anadyrensis samples; we thus can conclude little regarding the status or history of that subspecies, which has a distinct migration route through eastern Russia but an incompletely described non-breeding range (Chan et al, 2022;Tomkovich, 2010). However, the three samples in our final data set did not cluster together, grouping with either menzbieri (n = 1) or baueri (n = 2; Figure 2).…”

“…anadyrensis, which has a poorly described non-breeding range (Chan et al, 2022) but is believed to number <10,000 individuals. The species is considered Near Threatened by the IUCN based on widespread population declines, particularly associated with limitations at migratory stopover sites (Rakhimberdiev et al, 2018;Studds et al, 2017), although the nominate European-wintering population L. l. lapponica is thought to be increasing (BirdLife International, 2023).…”

“…There are up to six recognized subspecies of bar-tailed godwits, with distinct breeding areas and migratory routes (Figure 1), and further distinguished by variation in plumage and body size (Bom et al, 2022; Engelmoer & Roselaar, 1998; Tomkovich, 2010). Based on non-breeding census data, population sizes for these subspecies vary from c. 100,000 to 500,000 individuals (Wetlands International, 2023), except for the subspecies L. l. anadyrensis , which has a poorly described non-breeding range (Chan et al, 2022) but is believed to number <10,000 individuals. The species is considered Near Threatened by the IUCN based on widespread population declines, particularly associated with limitations at migratory stopover sites (Rakhimberdiev et al, 2018; Studds et al, 2017), although the nominate European-wintering population L. l. lapponica is thought to be increasing (BirdLife International, 2023).…”

High dispersal ability versus migratory traditions: Fine‐scale population structure and post‐glacial colonisation in bar‐tailed godwits

“…Due to the small number and high sequencing failure rate of purported anadyrensis samples in our study, we could not resolve the status or history of that subspecies, which has a distinct migration route through eastern Russia but an incompletely described non-breeding range (Chan et al, 2022;Tomkovich, 2010). The three samples in our final data set did not cluster together, grouping with either menzbieri (n = 1) or baueri (n = 2; Figure 2), suggesting that these individuals, sampled in southeast Chukotka, were most likely passage migrants from the neighbouring subspecies, rather than from the closest breeding population (Figure 1).…”