Five Commerson's dolphins that had become stranded by the falling tide in a small island off West Falkland were rescued Monday by researchers working in the area.
Actually the 10 year child of one of the couple of researchers discovered the distressed dolphins in shallow water between rocks and a dense kelp bed at Bense Island in Port North, on the west side of West Falkland.
With the help of the rest of the team from the Sub-Antarctic Foundation for Ecosystems Research, SAFER, (*) the dolphins were freed after cutting a path through the kelp to deeper water forty metres away.
As it was still several hours before the full low tide the trapped dolphins would have dried completely had they not been taken back into deeper water.
The smallest two were carried while the others were gently lifted and ushered into deeper water. The five finally made it to the open sea.
The Commerson dolphins can be found in shallow waters along the southernmost tip of South America and around the Kerguelen Islands in the Indian Ocean. They can often be found in naturally protected waters or harbors, sometimes entering the mouths of rivers. These dolphins prefer more coastal waters, and are most commonly found in the Straits of Magellan, the Falkland Islands, and around Tierra del Fuego, often around kelp beds.
While they may look like porpoises with their stocky body shape and their small, indistinct rostrum, the Commerson's dolphin is unmistakably part of the dolphin family with its bold, outgoing behavior. Because of its striking black and white patterns, this dolphin is also called by other names such as the Skunk dolphin and the Piebald dolphin. Typical coloration of an adult would be a black colored head, with a large black area sweeping back from the dorsal fin to the flukes. It has a white patch on its throat that travels beneath its pectoral fins, then sweeps upwards, covering the whole midsection of the dolphin in white, with a small black patch on the underside that may come up slightly to the sides of the dolphin.
At birth, these dolphins don't have the flashy black and white pattern, but are grey, black, and brown. As it grows older, it will become black and grey, with the grey patches developing into the white coloration that the adults possess.
Unlike most dolphins, the dorsal fin of the Commerson's dolphin is wide and rounded. It may curve back slightly, though some individuals have a less rounded find that is almost triangular in shape. Their pectoral fins are rounded as well, and are a solid black on both the top and the undersides.
They have a wide range of foods as part of their diet consuming various sea life such as fish, squid or octopus, crustaceans such as shrimp, and some other invertebrates as well, most likely foraging near the sea floor for their meals.
Gestation is about 11-12 months and at birth Commerson's dolphin calves are fairly large - almost half the size of their mothers. They can measure anywhere between 22 to 30 inches in length (56 - 76 cm) and can live into their late teens.
(*) The SubAntarctic Foundation for Ecosystems Research (SAFER) purchased Bense, Little Bense and Cliff Islands off West Falkland in 1996 and since 2001 has carried out annual research trips to the islands.
Over the past five years Bense Island has been the base for a series of visits by researchers who have been obtaining baseline information on the biology of the islands. Initial research has focused on an inventory of the flora and fauna already on the islands. Baseline data for comparison with any changes over time and will be particularly important in measuring changes related to environmental restoration projects. Various species will also be investigated as part of more intensive behavioural and ecological studies.
Upon completion of the biological inventories, Bense Island will be the focus of ecological and restoration work.
The largest and most modified of the parcel, Bense has been grazed by sheep, cattle, horses, and rabbits, although, only rabbits remain. Rats, accidentally introduced in the 19th Century, are also present. In addition, a fire in 1985-86 burnt about 15% of the island. However, a wide variety of plants and animals can still be found on the remainder of the island.
Little Bense Island is only 200m off Bense Island but appears to be in much better ecological condition. Grazing pressure has been slight and there has been no fire, but rats are present. Little Bense is home to a colony of about 60 South American sea lions and a wide variety of birds.
Cliff Island is ecologically pristine and has never been inhabited or modified by human activity, probably because there are no easy landing sites. It is situated about 1.2 nautical miles from Bense Island and is completely covered by tussock grass. This island supports a wide variety of both sea and land birds and could be a valuable source of plants for the re-vegetation work to be done on Bense Island.
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