To fly, walk or dive: what costs more? The Imperial Cormorant as a case of study

Birds capable of moving in air and water are expected to face some energetic constraints. For example, small wings with little air trapped between feathers diminish floatability and enhance diving capacity however; they are associated with the high energetic costs of flight. All cormorant species (with the exception of the Galapagos Cormorant Phalacrocorax harrisi) walk, fly to their feeding areas and dive to find food. We present the costs of walking, flying and diving of the Imperial Cormorant (P. atriceps). Moreover, we show how changes in the time and energy spent flying and diving to different depths affect the total energetic cost of the Imperial cormorants´ foraging trips. Finally, we present how the costs of flying and diving to different depths can be used to construct an energy landscape of the area around a breeding colony. The determination of the energy landscape around breeding sites is not minor since it may help us understand the coastal distribution of diving seabirds. All energetic cost estimations were determined by means of recording the overall dynamic body acceleration (ODBA) of breeding Imperial cormorants carrying electronic devices.