Shrinking Pelican Nesting Grounds May Pose a Problem
Rising lake levels are causing the pelican nesting grounds in the northern US to shrink, and though they have yet to affect nesting activity thus far, federal wildlife officials are concerned that it eventually means bad news for the animals.
About 30,000 pelicans returned to the 4,385-acre Chase Lake National Wildlife Refuge in North Dakota, known as North America's largest pelican refuge, to find several acres of their main nesting land submerged under water, the Associated Press (AP) reported.
Despite the cramped conditions, these birds - which weigh up to 20 pounds, have a wingspan of nearly 10 feet and measure 6 feet from bill to tail - seem to be coping with the shrunken space, even as the grounds are teeming with thousands of squawks and grunts.
American white pelicans descend on the tiny island each year to raise their young, coming from as far away as the Gulf Coast and California. Not only is this area prime nesting ground, but the lake is also shock full of fish and salamanders to feed on.
According to Neil Shook, a US Fish and Wildlife Service biologist and refuge manager, the lake has been diminishing by a couple of acres annually since the early 1990s. But this year in particular is causing concern because lake levels appear to have mysteriously decreased from 24 acres last year to about 15 acres this year - a loss in land mass equal to about nine football fields.
"As the water level at Chase Lake continues to rise, we're losing a little of the nesting island each year," Shook told the AP.
Not only that but Chase Lake, which is already known for having a high alkalinity that makes it unable to support aquatic life, is changing as water inundates the area.
"The lake is changing and becoming more of a freshwater lake even to the point that it now has a few minnows and salamanders but not enough for the pelicans to feed on," Shook added. "I don't think change in water chemistry is enough to make the birds leave but losing nesting habit - that could be an issue."
This is not the first time this pelican rookery has puzzled scientists. A decade ago, the Daily Digest News reported, a swarm of pelicans abruptly left their nesting grounds, abandoning their chicks and eggs. And the following year, there was a massive die-off of pelican chicks, followed by an exodus of their parents from the wildlife refuge.
In terms of this latest mystery, wildlife officials are not yet worried. The birds have been in this predicament before, when their previous nesting grounds were flooded, forcing them to Chase Lake instead. And rising lake levels can also form other small peninsulas adequate for nesting as well.