FAMILY PHOCIDAE Earless Seals
Both species of elephant seal are regularly seen tossing sand or pebbles onto their backs with alternating strokes of their flippers. One function of “sand flipping” appears to be to help the animals keep cool, by covering the skin in wet material, and at the same time, creating a depression that brings more of the body’s surface into contact with the damp substrate. The Southern Elephant Seal colony on the Valdes Peninsula, Argentina, the location of these pictures, lies in more temperate latitudes than the majority of sites used by this species. Temperatures at midday range around 20°C, and occasionally as high as 30°C, compared to highest temperatures of 5°C at some subantarctic rookeries. The rate of sand flipping increases as temperatures increase, and by noon some individuals will have covered more than one-half their upper body surfaces in sand or pebbles. In Northern Elephant Seals (Mirounga angustirostris), sand flipping is part of a gradient of responses to increasing solar radiation. Individuals first expose their more reflective undersides to the sun, then sand-flip, and finally go into the water. The behavior is innate: neonatal elephant seals perform sand-flipping movements within minutes of birth. Neonates have darker skin that absorbs more heat, and they flip sand at higher rates than their mothers, while mothers have been seen to flip sand over their offspring. Elephant seals also flip sand at night and in cool rainy weather, which indicates that it has other behavioral functions, perhaps as a displacement activity. Males flip sand when disturbed or aroused, and females flip sand continually during copulation. Elephant seals may also go through sand-flipping motions on inappropriate substrates, such as rock. The South American Sea Lion (Otaria byronia), which also breeds on the Valdes Peninsula, is one of a number of sea lion species that flip sand over themselves on hot days. Above: Mirounga leonina Valdes Peninsula, Argentina. Photo: Günter Ziesler
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Below: Mirounga leonina Valdes Peninsula, Argentina. Photo: Eberhard Hummel
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