5 Jan 2010

Whales saving seals

Survey to the Antarctic Peninsula lead scientists of NOAA Fishery Service to an interesting discovery, which was published in a popular article in the Natural History Magazine. The first author Robert L. Pitman has kindly allowed us to post this on Morigenos Blog.

The aim of the survey was to document remarkable hunting technique of the resident killer whales. The whales swim side by side to create a wave that washes the seal off an ice floe. Video of the hunt: http://www.orcaresearch.org/video_orca.htm.

After locating a pod of killer whales with satellite transmitters, the scientists noticed two humpback whales nearby. The whales seemed agitated by the killer whales’ presence, although they were not under attack. When researchers reviewed video footage, they noticed a seal between the humpbacks, which is what the killers were probably after. Later on, the pod tried to catch another seal, resting on the ice floe. In that moment, the same two humpback whales swam onto the scene, bellowing and thrashing around. The humpback whales were apparently harassing the killer whales and interrupted their action.

A week later the scientists spotted a different pod of killer whales, attempting to catch a seal resting on an ice floe. Two humpback whales were involved in the fight once again, but they were not the same two individuals as in the week before. When the killers washed the seal off the ice floe, it swam towards the humpbacks, seeking shelter. One of them turned belly-up, and placed the seal between its flippers. When killer whales moved closer it arched its chest out, which lifted the seal out of the water. When the seal started sliding towards the water, the whale pushed it back onto its chest with a flipper. Moments later the seal scrambled off and swam to the safety of a nearby ice floe.

Humpbacks have shown maternal instinct in this dangerous situation, although they did not have calves of their own. Allomaternal care has been seen recorded in several species. When a human protects an individual of another species, we call it compassion. If a whale does so, we call it instinct. But sometimes the distinction isn’t all that clear.

Source: R. Pitman and J. Durban. 2009. Save the seal! Nat. Hist. Mag. Nov. 2009.

Photo: Robert L. Pitman

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