PREY INGESTION REVEALED BY ESOPHAGUS AND STOMACH TEMPERATURE RECORDINGS IN CORMORANTS

We examined the accuracy of both stomach and oesophagus temperature se nsors - deployed on captive Brandt's cormorants - for determination of the mass of food ingested and the number of prey items swallowed. The oesophageal temperature sensor was a better detector of all feeding e vents, including that of small prey which were missed by the stomach s ensor. Adapted to free-ranging (and coupled to data loggers for record ing temperature), oesophagus temperature recorders, in conjunction wit h both recordings of energy expenditure (e.g. doubly labelled water, h eart rate) and determination of position (e.g. Argos transmitter, time /depth recorder), should provide further important insights into the f oraging success of marine endotherms.