Site fidelity and recurrence of some migrant bird species in The Gambia

Abstract

Regular ringing was carried out over most of five winters at Ginak in The Gambia. We analyse retrap data from 12 species of migrant birds to examine whether they remain for more than one day within a winter, and whether they return to the study area in subsequent winters. We investigate both the rate of recurrence (between‐winter retraps within the whole area, approximately 1,000m across) and site fidelity (tendency to be retrapped within 100m of first capture). Some adjustment of recurrence for annual survival is attempted. For individuals trapped at least twice over a winter, we tabulate the interval between first and last capture: in all 12 species this was over six weeks for some individuals; furthermore, site fidelity within a winter is demonstrated in most species retrapped in reasonable numbers, exceptions were Garden Warbler Sylvia borin and Blackcap Sylvia atricapilla. Most species recurred at appreciable rates in successive seasons, and in three species with a sufficient sample size, Subalpine Warbler Sylvia cantillans, Whitethroat Sylvia communis, and less certainly Olivaceous Warbler Hippolais pallida, the evidence was of site fidelity between winters. We compare recurrence rates with data collected at Djoudj in north Senegal.