Recent Advances in Studies of the Diving Behavior of Marine Birds and Mammals with Micro-data Loggers

Abstract

The diving behavior and physiology of birds and mammals has been studied for more than a century. From the early 1940s many physiological studies of diving responses in the vascular system were conducted under forced-submerged conditions, despite it being known that the responses differed between voluntary diving and enforced-submerged animals. Accordingly, new attempts to study freely diving animals were begun. The first success was achieved in 1965 by Kooyman, who used a mechanical time depth recorder (TDR) to monitor the diving behavior of Weddell seals, Leptonychotes weddelli. Thereafter, in the 1980s marked advances in experimental apparatus revealed many unexpected diving abilities of penguins and seals. More recently, in addition to interest in their physiology, the foraging ecology of free diving animals has attracted considerable interest, and has stimulated the accelerated development and miniaturization of electronic data loggers. Currently, data loggers that record depth, swimming speed, light level, ambient, esophagus and body temperature, acceleration, geo-magnetic field, heart rate, ECG, EMG, visual image, etc., are available as tools to study foraging ecology, physiology and biomechanics. This technology has brought new advances in bio-logging science, which utilizes integrated microsystem technology to study the lives of animals in aquatic and other remote environments. This paper reviews recent technological advances in this field, with special attention to activities in Japan and the roles of these advances in the study of diving by marine animals.