Behavior and seasonal abundance of Neotropic Cormorant Nannopterum brasilianus (Gmelin, 1789) in southeastern, Brazil

The Neotropic Cormorant Nannopterum brasilianus (Gmelin, 1789) is one of the most common and abundant species in Brazil’s aquatic environments, but little is known about its natural history. This study elaborates and quantitatively evaluates the ethogram and seasonal abundance of this species at Lake Açu, in Rio de Janeiro, Brazil. Between August 2013 and July 2014, behaviors were registered by the ad libitum sampling method and quantified by the continuous recording during 30-min sessions. The mean number of sighted individuals per month was 30.41 ± 4.79. Abundance was higher during the dry season (41.5 ± 5.36) compared to the rainy season (19.33 ± 4.81) ( t = 3.07, P = 0.01). A total of 42 behaviors were described and grouped into five behavioral categories: maintenance (83.59%), ingestion/excretion (10.67%), locomotion (3.48%), play (1.65%), and agonistic behavior (0.61%). The time spent in these categories did not vary significantly between the morning and afternoon periods. This study can be used as a starting point for further ethological studies on the species.