Nesting pelicans near record numbers at ND refuge
BISMARCK, N.D. (AP) -- Less than a decade after thousands of pelicans inexplicably died or abandoned a refuge in southern North Dakota, the giant, big-billed birds are nesting there in near record numbers, and they have been joined by an increasing number of other water bird species.
Hundreds of herons and egrets are nesting alongside the American white pelicans on a guano-rich island that serves as a rookery at the Chase Lake National Wildlife Refuge, said Neil Shook, a U.S Fish and Wildlife Service biologist and the refuge manager. About 5,000 gulls are nesting on a nearby island.
"It's truly amazing out there," Shook said.
The pelican colony at the 4,385-acre refuge north of Medina has been the largest in North America, peaking at 35,466 birds in 2000. A preliminary count this year shows 31,534 breeding adults, up from 20,854 in 2011, Shook said.
But in 2004, thousands of adult pelicans at the refuge abruptly left their chicks and eggs and a year later, masses of pelican chicks died, prompting another exodus of mature birds. Predators, weather, diseases and other factors were considered but biologists have never pinpointed the cause of the pelican deaths and departures.
Shook said it may have just been a natural correction.
"To this day we haven't found one single cause," he said. "But every year since then, we've seen a steady increase in the birds."
Pelicans appear healthy at the refuge this year, Shook said.
"There is no indication of anything negative with the colony at this point," Shook said Tuesday. "But we never know for sure. It is nature."
The white pelican is among the largest birds in North America. They breed once a year, and males and females take turns caring for their young. The birds have a wingspan of nearly 10 feet and live for about 25 years.
The pelicans winter mainly in the Gulf Coast states but some fly to the North Dakota nesting grounds from as far away as Florida and California.
Pelicans typically begin returning to Chase Lake in early April and stay through September, caring for their hatchlings. The lake is alkalized, free of fish and other food sources, so the pelicans feast on small fish and foot-long salamanders from prairie lakes up to 100 miles away.
Pelicans have been monitored at Chase Lake since 1905, when the birds numbered about 50. President Theodore Roosevelt designated the site as a bird refuge in 1908, when many of the birds were being killed for their feathers and for target practice.
Biologists began conducting aerial surveys of the nesting grounds in 1972. They scan photographs of the refuge into a computer program to estimate the number of breeding birds, based on the number of nests.
Shook said biologists began counting other bird species at the nesting grounds for the first time this year. That census is being done by biologists on the ground and is not yet completed, he said.
Herons and egrets nest in shrubs, and build their nests on top of one another, "sort of a high-rise condo," Shook said.
Those species began appearing at Chase Lake in the late 1990s and their numbers have increased dramatically over the past few years. Shook estimated there are 3,000 to 5,000 nests of herons and egrets that now share the pelican rookery.
One nest belongs to a great blue heron, a first for the area, Shook said.
"This is becoming one of the most important mixed species water bird colonies in Upper Midwest, and possibly, the United States" Shook said. "It's just incredible."