Wednesday, October 3, 2007

Laysan duck boom on Midway

The great Laysan duck expansion on Midway Atoll is going gangbusters.

The population on Midway is now roughly a quarter that on Laysan, and it's still growing.

It's a really successful attempts to provide an endangered population with the protection created by having a backup home turf.

Laysan ducks (Anas laysanensis), sometimes called Laysan teals, once occurred throughout the Hawaiian Islands, but their populations were destroyed off Laysan Island in the Northwestern Hawaiian Islands. The loss of the animals may have been due to human predation, rats, habitat loss and other factors.

Laysan, a sandy island with a central super-salty lake, was their last refuge. A century ago, their population was down to about a dozen birds. With the removal of the last rabbits, which had eaten most of the plants on the island, the vegetation and the ducks started to recover.

Still, fearful that a tsunami, a hurricane or other disaster could wipe out the last of the Laysan ducks, biologists decided to establish a second population at Midway Atoll. Workers dug pits down to the water table, to provide a little wetland habitat. The crew of the voyaging canoe Hokule'a got into the act by transporting from Laysan to Midway some of the sedges that the ducks favor, and they were planted along the ponds..

And in late 2004, a group of 20 ducks was transferred from Laysan to Midway, followed by 22 more in 2005. They thrived, wrote John Klavitter, biologist with the Midway Atoll National Wildlife Refuge.

“The ducks are doing great.

“In 2005 we had 12 fledglings. 2006 we had 60. In 2007 thus far we have at least 100 and are hopeful for 150,” Klavitter said in an email.

“With 100 fledglings confirmed so far, our population is about 200. It's amazing to
see this success with an original founder population of 42,” he said.

An update on the ducks was printed in the new newsletter, Ka Palapala Ho'omaopopo, of the Papahānaumokuākea Marine National Monument. It said volunteers have worked 20,000 hours building the habitat, clearing weeds and planting the species the ducks prefer.

“Lots of people have made this project possible - Michelle Reynolds, Mark Vekasy, Leona
Laniawe, Jimmy Breeden, myself, many many volunteers, and many more people,” Klavitter said.

© 2007 Jan W. TenBruggencate

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