Balancing foraging and reproduction in the male harbour seal, an aquatically mating pinniped

Variation in sexual behaviors in a group of captive male Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis): motivated by physiological changes?

“…For instance, in various species such as lesser galagos (Galago moholi) [2], roe deer (Capreolus capreolus) [3], domestic stallions [4], and domestic rams [5], sexual behaviors vary in parallel with changes in testicular volume or serum testosterone concentration. Seasonal reproduction has also been described in aquatic mammals, including sea lions (Eumetopias jubatus) [6], manatees (Trichechus manatus manatus) [7], and seals (Phoca vitulian) [8]. Male cetaceans are reported to enter a resting phase in the nonbreeding season, during which testis size decreases and sex hormones decline, as demonstrated in common dolphin (Delphinus delphis) [9], white-sided dolphin (Lagenorhynchus acutus) [10], and blue white dolphin (Stenella caeruleoalba) [11].…”

Foraging tactics of Baikal seals differ between day and night

“…Penguins, for example, are primarily diurnal foragers (Wilson et al 1993, Pütz & Bost 1994, Pütz et al 1998, Bost et al 2002 while fur seals are generally nocturnal foragers (Croxall et al 1985, Boyd & Croxall 1992. On the other hand, some pinniped species appear to forage during both daylight and darkness (Kooyman 1975, Le Boeuf et al 1988, 2000, Feldkamp et al 1989, Coltman et al 1997. Different tactics could be used during the day and at night because of changes in the relative importance of the predator's sensory systems and because many aquatic organisms, including pinniped prey, make diel vertical migrations (e.g.…”

Diving behaviour during the breeding season in the terrestrially breeding male grey seal: implications for alternative mating tactics

“…This assumption was based on dietary (Bowen and Harrison 1994;Hammond et al 1994) and telemetry (Thompson et al 1991;Thompson and Fedak 1993) studies suggesting that grey seals are benthic foragers, and studies on the foraging behaviour of harbour seals (Coltman et al 1997;Bowen et al 2002) suggesting that most foraging occurs during deep rather than shallow dives. We therefore calculated diving effort separately for shallow and deep dives as the total time spent at the bottom of the dive per day as an estimator of foraging effort (after Beck et al 2003):…”

“…Several studies have associated bouts of relatively deep diving by male phocids during the breeding season with foraging behaviour (Coltman et al 1997;Lesage et al 1999). Given the positive correlation between length of tenure and mating success in grey seals, males may forage during the breeding season to increase their length of tenure at the breeding colony either by accumulating additional energy reserves or by decreasing the loss of stored reserves.…”

“…We did this by studying the characteristics of diving behaviour known to be associated with foraging in other pinniped species (e.g., Lesage et al 1999;Baechler et al 2002). Secondly, as male age and size are often implicated in alternative male mating tactics and may play a role in energy constraints (Le Boeuf 1974;Clutton-Brock et al 1982;Dunbar 1982;Caro and Bateson 1986;Coltman et al 1997), we examined the effects of male phenotype on diving behaviour.…”