Diving behaviour of Mediterranean monk seal pups during lactation and post weaning

Abstract

Time depth recorders (TDRs) were attached to 3 Mediterranean monk seal pups during a range of periods around weaning, providing a composite picture of activity from the first weeks of life until nutritional independence. The pups entered the water during their first week of life and their diving performance increase progressively with age. All pups spent most of their time at sea (55 to 74%), and their swimming activity was greater at nighttime compared with daytime. Dive performance in relation to pup age was poorer compared with other phocid seal species. Dive types were classified using a combination of hierarchical and k-mean clustering. We found 3 dive types: 1 V-shaped and 2 U-shaped. The most common type was U1-dives, mainly used by older pups during 44 to 48% of their total dive time. These dives were relatively deep and long (mean depth = 11.6 ± 9.5 m, mean duration = 149.1 ± 80.6 s). They had long bottom times (100 ± 67 s), suggesting that pups were foraging. Pups appeared to start feeding at the end of lactation. © Inter-Research 2006.