Tracking the full annual-cycle of the Great Knot, Calidris tenuirostris, a long-distance migratory shorebird of the East Asian-Australasian Flyway

The Great Knot Calidris tenuirostris is one of the iconic long-distance migratory species of the East Asian-Australasian Flyway. However, despite extensive flagging and banding efforts, very little is known about the migratory strategies and the breeding grounds of this species that spends the non-breeding season mainly on the northern shorelines of Australia. Using light-level geolocators deployed on Great Knots at Roebuck Bay (Western Australia), we describe the individual migration strategies, breeding locations and breeding-related behaviour. Based on data from eight successfully tracked individuals, we found that all except one migrated to the western part of the known breeding range. This was 2,000–2,500 km from the eighth individual that commenced breeding in the potentially separated eastern part of the range. Light intensity and temperature profiles provided evidence that four of the birds successfully hatched chicks. Of the three which failed, one appeared to have laid a second clutch before failing again. Arrival at the breeding grounds and the laying of eggs were remarkably synchronous between individuals, as were the arrival dates back at Roebuck Bay. Departure from the breeding grounds was more spread out, partly dependent on breeding success and also as a result of females probably leaving the nesting area before males. The individual migration strategies confirmed the strong dependence of this species on the Yellow Sea as their major stopover site during both southward and northward migration. Furthermore, all individuals stopped at least once on their northward journey to the Yellow Sea from Australia. And in reverse, all individuals stopped at least once on the southward migration before arriving at the Yellow Sea coming from their Arctic breeding grounds. The results indicate that this species will most likely be further affected by the rapid habitat loss in the area of the Yellow Sea and other parts of the Chinese coastline.