| Abstract: | Capsule Common Sandpiper populations at the edge of their range do not recruit so well. Aims To compare the survival rates, breeding success and recruitment of a population near the edge of its range (Peak District) with one more centrally placed (Borders). Methods Populations were censused weekly; adults and chicks were ringed, and apparent survival of adults determined by resighting colour-ringed birds. Breeding success was assessed from ringing chicks and the guarding behaviour of their parents over 3–4 weeks post-hatching. Results Survival rates of adults and their breeding success were similar in the two sites. Recruits were rarely ringed chicks returning to near their natal site; they were usually newly recruited adults. In both, natal dispersal took returning chicks away from their natal site, by 3–6 km, but far more potential recruits returned to the Borders (51% compared with 4%). The population in the Borders was more variable, but recovered better from declines. Conclusions There is no obvious difference in survival or reproductive rates that would explain the different recent fates of the two study populations. Differential survival over winter in West Africa (the presumed wintering grounds) is unlikely to explain the recent decline of the Peak District population, because conditions there should have affected the Borders population too. The Peak District population is exposed at the edge of the species' range, and it seems to be poorer breeding success across its general range that has caused the poorer recruitment there, and hence the decline. |
