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Difference between revisions of "Southern elephant seal"
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==Behavior== | ==Behavior== | ||
===Social behavior and reproduction=== | ===Social behavior and reproduction=== | ||
[[File:ElephantSeal.jpg|thumb|right| | [[File:ElephantSeal fighting.jpg|thumb|right|Bull elephant seals fighting over a harem of females]] | ||
Elephant seals are among the seals that can stay on land for the longest periods of time, as they can stay dry for several consecutive weeks each year. Males arrive in the colonies earlier than the females and fight for control of harems when they arrive. Large body size confers advantages in fighting and the agonistic relationships of the bulls gives rise to a dominance hierarchy, with access to harems and activity within harems being determined by rank. The dominant bulls (“harem masters”) establish harems of several dozen females. The least successful males have no harems, but may try to copulate with a harem male's females when the male is not looking. The majority of primiparous females and a significant proportion of multiparous females mate at sea with roaming males away from harems. | Elephant seals are among the seals that can stay on land for the longest periods of time, as they can stay dry for several consecutive weeks each year. Males arrive in the colonies earlier than the females and fight for control of harems when they arrive. Large body size confers advantages in fighting and the agonistic relationships of the bulls gives rise to a dominance hierarchy, with access to harems and activity within harems being determined by rank. The dominant bulls (“harem masters”) establish harems of several dozen females. The least successful males have no harems, but may try to copulate with a harem male's females when the male is not looking. The majority of primiparous females and a significant proportion of multiparous females mate at sea with roaming males away from harems. | ||
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===Feeding and diving=== | ===Feeding and diving=== | ||
Satellite tracking revealed the seals spend very little time on the surface, usually a few minutes for breathing. They dive repeatedly, each time for more than 20 minutes, to hunt squid and fish at depths of 400 to 1,000 m (1,300 to 3,300 ft). They are the deepest diving air-breathing non-cetaceans and have been recorded at a maximum of 2,133 m (6,998 ft) in depth. | Satellite tracking revealed the seals spend very little time on the surface, usually a few minutes for breathing. They dive repeatedly, each time for more than 20 minutes, to hunt squid and fish at depths of 400 to 1,000 m (1,300 to 3,300 ft). They are the deepest diving air-breathing non-cetaceans and have been recorded at a maximum of 2,133 m (6,998 ft) in depth. | ||
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===Predation=== | ===Predation=== | ||
Weaned pups, juveniles and even adults of up to adult male size may fall prey to [[orca|orcas]]. Cases where weaned pups have been attacked and killed by [[leopard seals]] (''Hydrurga leptonyx'') and New Zealand sea lions (''Phocarctos hookeri''), exclusively small pups in the latter case, have been recorded. Great white sharks (''Carcharodon carcharias'') have hunted elephant seals near Campbell Island, while bite marks from a southern sleeper shark (''Somniosus antarcticus'') have been found on surviving elephant seals in the Macquarie Islands. | Weaned pups, juveniles and even adults of up to adult male size may fall prey to [[orca|orcas]]. Cases where weaned pups have been attacked and killed by [[leopard seal|leopard seals]] (''Hydrurga leptonyx'') and New Zealand sea lions (''Phocarctos hookeri''), exclusively small pups in the latter case, have been recorded. Great white sharks (''Carcharodon carcharias'') have hunted elephant seals near Campbell Island, while bite marks from a southern sleeper shark (''Somniosus antarcticus'') have been found on surviving elephant seals in the Macquarie Islands. | ||
==Conservation== | ==Conservation== | ||