Nesting success of common eiders Somateria mollissima as influenced by nest-site and female characteristics in the Gulf of the St. Lawrence
François Bolduc, Magella Guillemette & Rodger D. Titman
Bolduc, F., Guillemette, M. & Titman, R.D. 2005: Nesting success of common eiders Somateria mollissima as influenced by nest-site and female characteristics in the Gulf of the St. Lawrence. - Wildl. Biol. 11: 273-279.
In the common eider Somateria mollissima as well as in many other bird species, nesting success has been associated with female reproductive characteristics and predator accessibility to the nest site. In this study, we tested the following predictions on nesting common eiders: 1) female and nest-site characteristics are correlated within a colony, where those with the highest ranked reproductive traits nest where the environment provides best protection, 2) females nesting on forested islands generally exhibit better reproductive traits than females nesting on open islets (hereafter habitats) because the former provide the best nest protection, and consequently, 3) colonies located on forested islands have higher nesting success than those on open islets. During the summers of 1995 and 1996, we recorded nesting success at 270 eider nests on two forested islands and four open islets. Simultaneously, we measured several variables describing nest (nest concealment, vegetation height, distance to shore and density of associated nesting gulls) and female (laying date and clutch size) characteristics. Using factor analysis to relate nest-site and female characteristics, we found a correlation between factor scores within four of the six colonies monitored. This correlation indicated that females with largest clutch size and early laying were associated with nest sites of low concealment that were close to shore. However, female score did not differ with habitat. Nesting success did not differ between habitats when controlled for female and nest scores, but was related to female score, and marginally to nest-site score. Because nesting success was principally related to female characteristics rather than to nestsite characteristics, we suggest that eiders rely on nest attendance rather than on nest concealment to protect their nests. Nesting close to shore may shorten incubation recesses and improve hatchling survival when leaving the nest.
Key words: common eider, female, Gulf of St. Lawrence, human disturbance, nest, nest concealment, nest success
François Bolduc*, Magella Guillemette** & Rodger D. Titman, McGill University, Macdonald Campus, 21 111 Lakeshore, Ste-Anne-de-Bellevue, Québec, Canada, H9X 3V9 - e-mail addresses: firstname.lastname@example.org (François Bolduc); email@example.com (Magella Guillemette); firstname.lastname@example.org (Roger D. Titman)
*Foramec inc., 70 Rue St-Paul, Quebec City, QC, Canada, G1K 3V9
**Université du Québec à Rimouski, Département de Biologie et des Sciences de la Santé, Rimouski, Québec, Canada, G5L 3A1
Corresponding author: François Bolduc
Received 6 October 2003, accepted 16 August 2004
Associate Editor: Kjell Einar Erikstad