Fledging success of wader chicks, estimated from ringing data

Abstract

From 1976 to 1985 large numbers of chicks of Lapwing Vanellus vanellus, Black‐tailed Godwit Limosa limosa, Redshank Tringa totanus, and Oystercatcher Haematopus ostralegus have been aged during ringing in The Netherlands in a large scale programme involving many volunteers. Hatching dates have been calculated from ringing dates (corrected for estimated age at ringing). Distributions of hatching dates in the province of Frisia differ from elsewhere, because of egging (Lapwing eggs are taken), and the associated activities of nest protection. Hatching dates of Frisian Lapwing are strongly synchronised, not only because of a peak in replacement clutches after the closing of the egging season, but also as a result of nest protection, which precludes the occurrence of many late replacement clutches. Synchronisation also characterizes the other species. Age-specific recovery rates from the same material have been used to estimate fledging success. Fledging success in the Lapwing may be positively correlated with rainfall in May, which is a major factor indirectly affecting chick condition. Chicks hatched in the early and late parts of the season tend to survive less well than those hatched in the middle. Survival rates are relatively high for chicks hatched between the 25th and 50th percentile of the distribution of hatching dates, with higher values for wet years than for dry years. Frisian chicks tend to survive less well than those elsewhere when still in the nest, and better when they are larger. These differences may be attributed to climatic differences, and to side‐effects of the Frisian system of nest protection. © 1995 Taylor & Francis Group, LLC.