A shared Himalayan route, but distinct origins and destinations: Common Redshank migration in the Central Asian Flyway

Common Redshanks Tringa totanus are shorebirds that breed in Eurasia and have a non-breeding range across the south of Eurasia, Africa and Australia. However, there is limited information on their migration behaviour in Central and Eastern Asia. This study documented nine Common Redshanks caught during the non-breeding season in southern Bangladesh and tracked on migration to their breeding grounds in Qinghai (north-west China) and Siberia over the Himalayan mountain range. These data were compared with Common Redshanks caught in Singapore during the non-breeding season, which also undertook the trans-Himalayan journey. We aimed to identify the unique features of Bangladesh-wintering individuals, by comparing the migration routes and breeding grounds of these two groups of trans-Himalayan migrants. We expected overlap between these two groups in general breeding areas and passage routes through the mountains, as both groups are likely to use the least energetically costly migration paths. Our tracking data revealed that the Bangladesh non-breeding individuals had a narrow migration corridor (4.72 ± 1.19 degrees of longitude) compared to individuals from Singapore (12.97 ± 3.45), and a shorter mean migration distance than migrants from Singapore. There was no clear overlap of breeding range even among individuals breeding in the Qinghai-Tibetan Plateau, despite the same path through the mountains being taken by both groups. Three individuals from Bangladesh bred outside the previously known breeding range; two in Qinghai, and one in Khakassia, Russia. This study further strengthens the need for more research and conservation of birds and wetlands along the Central Asian Flyway, including the understudied Qinghai-Tibetan Plateau region.