Breeding habitat availability and use by the Red-legged Cormorant (Phalacrocorax gaimardi): evidences of habitat selection process
MILLONES, A., FRERE E., & GANDINI, P.
We studied the breeding habitat availability and use by the Red-legged Cormorant (Phalacrocorax gaimardi), to identify the factors implicated in the habitat selection process. Along 21 km of the Ría Deseado, we recorded different characteristics at each cliff identified, including the distance to the nearest foraging area. Previous research had indicated that those zones with gravel substrate and depth less than 10 m were favoured foraging areas for this species. Of the 16 cliffs indentified, eight were used by Red-legged Cormorants to breed. The probability of occurrence of active nests increased with height and slope and decreased with the distance to the nearest foraging area. Significant differences were observed when use and habitat availability characteristics were compared. Cliffs higher than 12 m, steeper than 85° and nearer than 3 km from a foraging area were the most frequently used but they were not the most available. It seems that habitat characteristics that give protection and the proximity to an abundant food source are factors that influence the habitat selection process of the Red-legged Cormorant. In this study, we also demonstrated a non-random use of foraging locations. This species preferred zones with low water depths and grave substrate.