 An Elephant Seal Harem
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Aug. 7, 2003 — Recent research at nature reserves in Ghana has found that among mammals, monogamy may be a risk factor for extinction of their species.
According to the study done by Justin Brashares of the University of British Columbia in Vancouver, large mammals that live in pairs or with a small group of mates are far more likely to die out than those living with a large harem.
Brashares looked at census data for 41 species over the last 30 years and found that after population isolation, harem size was the second most important influence on a species' survival.
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Exactly how monogamy and extinction are tied together is still not known, but one theory is that hunters kill more males than females in a population, which could lead to a lack of males for pairing off in a monogamous species.
Species with large harems, on the other hand, will still have plenty of "spare" males left.
Another theory is that species living in pairs or small groups may not detect hunters as quickly as those in large groups.
This new finding is the first to show a strong link between social behavior and the risk of extinction in mammals.
"Many species that we assumed we didn't need to worry about are getting hammered as a result of their behavior," said Brashares.
Other factors in today's world — such as over-hunting, habitat destruction and other human-caused disturbances — may also have an effect on future extinction rates.
If conservationists can determine which species are most affected by these disturbances, they can concentrate their efforts to save the species.
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Name: Northern Elephant Seal (Mirounga angustirostris)
Primary Classification: Pinnipedia (Seals and Sea Lions) Location: Along the Pacific coast from Alaska to Mexico. Habitat: Rocky, muddy or sandy coasts and offshore islands, as well as coastal waters. Diet: Various fish, skates, small sharks, squids, crabs and octopus. Size: Up to 17 ft in length and 5,000 lbs in weight. Description: Gray or brown in color; males have an inflated proboscis and a chest shield; no external ears; short, coarse fur; relatively small front flippers; lobed hind flippers Cool Facts: It can dive to a depth of 1,500 ft and remain submerged for up to two hours. It is the only mammal known to make two long distance migrations in a single year, traveling up to 21,000 miles in a single year — the longest migration known for any mammal. Conservation Status: Common |
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