A new method for estimating the adult survival rate of the Corncrake Crex crex and comparison with estimates from ring-recovery and ring-recapture data
Abstract:The mean annual survival rate of adult Corncrakes Crex crex was estimated by three independent approaches: ring-recovery, ring-recapture and the shape of secondary remiges. The last method is new and uses measurements of the shape of the tips of the secondaries, which changes in the first post-juvenile wing moult to become less pointed. The estimates obtained by the three approaches were mutually compatible and indicated that annual survival is likely to be within the range 0.2–0.3. This low survival rate is likely to make the growth rate of Corncrake populations particularly sensitive to the effects of agricultural and conservation management on breeding success and recruitment. The survival rate of adult female Corncrakes was estimated for the first time (0.259) and was found not to differ significantly from an estimate for adult males (0.298) made in the same study area by the same method. It is concluded that the method based upon population counts and measurements of the shape of remiges has potential value for studies of the demography of Corncrakes and other species.
Document Type: Research Article
Publication date: July 1, 2004