Diving behavior of Red-legged Cormorant in southeastern Patagonia, Argentina

FRERE, E.; QUINTANA, F. & GANDINI, P.

THE CONDOR

COOPER ORNITHOLOGICAL SOC

Año: 2002 vol. 104 p. 440 - 444

0010-5422

We studied the diving behavior of Red-legged Cormorants (Phalacrocorax gaimardi) in Patagonia, Argentina, using VHF radio-transmitters deployed during incubation.  Red-legged Cormorants made foraging trips in inshore waters less than 15 m deep.  Mean dive duration was 26.8 ± 2.0 sec while mean time at surface was 9.2 ± 0.9 sec (n = 2217 dives).  The birds spent 74% of their foraging time underwater.  Diving efficiency was different between individuals, and was among the highest reported for the Phalacrocoracidae.  Dive variables were correlated with the height of the tide, suggesting that the birds forage on the seabed.  Red-legged Cormorants were efficient divers, investing most of their feeding time underwater and foraging in shallow waters, maximizing bottom time.  Our results are consistent with the hypothesis that Red-legged Cormorant diving behavior is strongly influenced by a combination of environmental variables (bottom heterogeneity and high tide width) characteristic of the south coast of Patagonia