The role of the Orkney Islands as a spring staging post for turnstones Arenaria interpres

Patterns of change in numbers and mass of Turnstones in two parts of Orkney during winter and spring were compared. On Mainland and South Ronaldsay, Turnstone numbers were generally stable during winter and then tended to decline in April, leaving few birds still present in May; prior to emigration an associated modest gain in mass occurred. In contrast, Turnstone numbers on Sanday and North Ronaldsay, in the north‐east of Orkney, increased considerably in late April and remained high well into May; large gains in mass were attained over this period and the proportion of adults caught was higher than that recorded on Orkney in winter. The possibility is discussed that Turnstones wintering on Mainland and South Ronaldsay migrate north in spring via staging posts in Iceland, whereas birds staging on Sanday and North Ronaldsay may fly directly to Greenlandic breeding grounds.