Abstract
During the last few years, the development of animal-borne still cameras and video recorders has enabled researchers to observe what a wild animal sees in the field. In the present study, we deployed miniaturized video recorders to investigate the underwater foraging behavior of Imperial cormorants (Phalacrocorax atriceps). Video footage was obtained from 12 animals and 49 dives comprising a total of 8.1 h of foraging data. Video information revealed that Imperial cormorants are almost exclusively benthic feeders. While foraging along the seafloor, animals did not necessarily keep their body horizontal but inclined it downwards. The head of the instrumented animal was always visible in the videos and in the majority of the dives it was moved constantly forward and backward by extending and contracting the neck while travelling on the seafloor. Animals detected prey at very short distances, performed quick capture attempts and spent the majority of their time on the seafloor searching for prey. Cormorants foraged at three different sea bottom habitats and the way in which they searched for food differed between habitats. Dives were frequently performed under low luminosity levels suggesting that cormorants would locate prey with other sensory systems in addition to sight. Our video data support the idea that Imperial cormorants’ efficient hunting involves the use of specialized foraging techniques to compensate for their poor underwater vision.
Highlights
The foraging behavior of seabirds has been difficult to study, principally because they spend most of their time at sea and obtain their food underwater
During the last few years, development of animal-borne still cameras and video recorders has enabled researchers to observe what a wild animal sees in the field (e.g. [7, 8, 9])
Fieldwork was conducted at Punta León provincial protected area (43°040S; 64°290W) in December 2011 and 2012 under the project “"Ecología pelágica de aves marinas buceadoras: determinación de movimientos y comportamiento en el mar mediante la utilización de registradores electrónicos de alta resolución" directed by Flavio Quintana and authorized by La Secretaria de Turismo y Áreas Protegidas (STyAP) and La Dirección de Fauna y Flora Silvestre (DFyFS) of the Province of Chubut
Summary
The foraging behavior of seabirds has been difficult to study, principally because they spend most of their time at sea and obtain their food underwater. Over the last 30 years, technological advances have resulted in the development of recording devices that can be attached to marine animals, providing information about their movements and behaviors at sea Imperial Cormorant Underwater Foraging Behaviour movement and behavior and on the physical characteristics (e.g., temperature, salinity) of the marine environment [1, 4, 5, 6]. All these devices only provide indirect information in the form of electronic signals and do not allow direct observation of the behavior or the environment visited by the tracked animal. The main disadvantage of current animal-borne cameras is the high power consumption and large storage space, which limit the recording period [9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
