DIVING BEHAVIOR OF THE SHY ALBATROSS DIOMEDEA-CAUTA IN TASMANIA - INITIAL FINDINGS AND DIVE RECORDER ASSESSMENT

The diving behaviour of the Shy Albatross Diomedea cauta was investiga ted using archival time-depth recorders (TDRs) and maximum depth gauge s (MDGs), Data from birds carrying multiple devices and from diving si mulations indicated that the degree oi. correspondence between TDRs an d MDGs varied with the dive depth, duration and frequency, as well as with body placement, The MDGs were the most reliable when the diving d epth was greater than 0.5 m, when the diving frequency was low and whe n gauges were placed on the birds' backs, The TDRs were used during la te incubation and early chick rearing in 1994, Fifty-two dives (greate r than or equal to 0.4 m) were recorded during 20 foraging trips of 15 individuals. The majority of dives were within the upper 3 m of the w ater column and lasted for less than 6 s, However, dives to 7.4 m and others lasting 19 s were recorded. The albatrosses dived between 07.00 h and 22.00 h, with peaks in their diving activity near midday and tw ilight, Mean diving depth varied throughout the day, with the deepest dives occurring between 10.00 h and 12.00 h, Two dive types were ident ified on the basis of the relationship between dive depth and descent rate, Plunge dives were short (less than or equal to 5 s), and the bir ds reached a maximum depth of 2.9 m. Swimming dives were both longer a nd deeper, The characteristics of Shy Albatross plunge dives were simi lar to those of gannets Morus spp,, which are known to be proficient p lunge di divers. Swimming dives suggest that Shy Albatrosses actively pursue prey underwater.