Availability and use of breeding habitat by the Red-legged Cormorant (Phalacrocorax gaimardi): evidence for habitat selection
Ana Millones A D , Esteban Frere A B C and Patricia Gandini A B CA Centro de Investigaciones de Puerto Deseado, Universidad Nacional de la Patagonia Austral, cc 238 (9050), Puerto Deseado, Santa Cruz, Argentina.
B Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), cc 238 (9050), Puerto Deseado, Santa Cruz, Argentina.
C Wildlife Conservation Society, Representación Argentina, Buenos Aires, Argentina.
D Corresponding author. Email: ana_millones@yahoo.com.ar
Emu 110(2) 155-159 https://doi.org/10.1071/MU09099
Submitted: 17 October 2009 Accepted: 3 February 2010 Published: 26 May 2010
Abstract
We studied the availability and use of breeding habitat by Red-legged Cormorants (Phalacrocorax gaimardi) to identify the factors involved in habitat selection. The species nests on cliff-faces. We identified cliffs suitable for nesting along 21 km of coastline of the Ría Deseado, and recorded the characteristics of each, including the distance to the nearest potential foraging area. Previous research had indicated that zones of the river with a gravel substrate and <10 m deep were preferred foraging areas for this species. Of the 16 cliffs identified as potential breeding sites, eight were used by Red-legged Cormorants for nesting. The probability of occurrence of active nests increased with the height and slope of cliffs and decreased with the distance to the nearest foraging area. Significant differences were observed between characteristics of cliffs that were used for breeding and those of available habitat in the environment. Cliffs higher than 12 m, steeper than 85° and within 3 km of a foraging area were the most frequently used but were not the most common in the environment. Factors that influence habitat selection by Red-legged Cormorants appear to be protection from predators and proximity to an abundant source of food. In this study, we also showed a non-random use of foraging sites. This species prefers zones with shallow water and gravel substrates.
Acknowledgements
The Universidad Nacional de la Patagonia Austral, Wildlife Conservation Society and the PME 2003 N° 271 (FONCyT) funded this work. We thank Juan Pablo Martin, Néstor Juanola, Adrian Pérez and Omar Juanola for field assistance. We also thank Annick Morgenthaler, Oliver Yates and two anonymous reviewers for advice on earlier versions of the manuscript.
Alldredge, J. R. , and Ratti, J. (1992). Further comparison of some statistical techniques for analysis of resource selection. Journal of Wildlife Management 56, 1–9.
| Crossref | GoogleScholarGoogle Scholar |
Frere, E. , Gandini, P. , and Quintana, F. (2002). Diving behaviour of the Red-legged Cormorant in southeastern Patagonia, Argentina. Condor 104, 440–444.
| Crossref | GoogleScholarGoogle Scholar |
Johnson, D. H. (1980). The comparison of usage and availability measurements for evaluating resource preference. Ecology 61, 65–71.
| Crossref | GoogleScholarGoogle Scholar |
Millones, A. , Frere, E. , and Gandini, P. (2005). Dieta del cormorán gris (Phalacrocorax gaimardi) en la Ría Deseado, Santa Cruz, Argentina. Ornitologia Neotropical 16, 519–527.
Millones, A. , Frere, E. , and Gandini, P. (2008). Breeding habitat use by Red-legged Cormorant (Phalacrocorax gaimardi) in Patagonia, Argentina. Waterbirds 31, 656–660.
Monaghan, P. , Walton, P. , Wanless, S. , Uttley, J. D. , and Burns, M. D. (1994). Effects of prey abundance on the foraging behaviour, diving efficiency and time allocation of breeding Guillemots Uria aalgae. Ibis 136, 214–222.
| Crossref | GoogleScholarGoogle Scholar |
Orians, G. H. , and Wittenberger, J. F. (1991). Spatial and temporal scales in habitat selection. American Naturalist 137, S29–S49.
| Crossref | GoogleScholarGoogle Scholar |
Siegel-Causey, D. , and Hunt, G. L. (1981). Colonial defence behaviour in Double-crested and Pelagic cormorants. Auk 98, 522–531.