It's been a good-news/bad-news summer for Minnesota's largest colony of American white pelicans.
The birds, about 17,000 pairs of them, nest each year at Marsh Lake in Lac Qui Parle County, on Minnesota's western border. The colony is summer home to 70 percent of North America's population of the birds and a third of the world's population.
The pelicans head south for the winter, many to the Gulf of Mexico. Birds from a given hatch will spend their first year entirely on the Gulf. They return here for mating in their second year.
Adult pelicans weigh roughly 11 to 19 pounds. Each day they'll eat 20 to 40 percent of their weight in fish and other aquatic creatures.
Pelicans use the very elastic pouch on the lower part of their bill to dip for food. The birds flush out bulging mouthfuls of water and eat the capture. But if there are chemicals in the food or water, they're now in the pelican.
Bad news first: You recall the massive BP oil spill two years ago. Some of our pelicans now have traces of oil and oil dispersant in their bodies. No one will say for sure that the chemicals came from the Gulf of Mexico, but the dispersant was used in the BP cleanup effort.
The chemicals moved from adults to eggs. Tests of eggs collected by biologists this spring found oil traces in 20 of the first 22 eggs examined. Corexit, the oil dispersant used in the cleanup, was found in 18 of those eggs. The study continues.
"Regardless of the source, the high prevalence of these contaminants in pelican eggs is troubling," wrote Sarah Courchesne in her blog on the Seabird Ecological Assessment Network website.
"Many petroleum-based products act as carcinogens or as endocrine disrupters, and need only be present in trace amounts to have profound effects," she wrote. "The embryonic birds are vulnerable to these foreign chemicals."
The pelicans are studied by DNR biologists on a regular basis, so comparisons past and present can be made. The samples currently are being analyzed in a lab at the University of Connecticut.
Five adult pelicans are now part of a study of where and when they go. Satellite-linked transmitters affixed to the birds send hourly signals. One piece of information sought is how the pelicans use the Gulf of Mexico in winter.
Common loons also winter on the Gulf. The Minnesota Department of Natural Resources, a partner in the pelican study, also is studying loons for oil-spill impact.
Now for the good news: Marsh Lake and its surrounds have been declared a Global Important Bird Area (IBA).
IBA is a worldwide effort to identify and conserve areas that are vital to birds and other biodiversity, according to the National Audubon Society. Audubon Minnesota was instrumental in securing the IBA designation.
Four other sites received IBA designation, chosen for their populations of greater prairie chicken, a grassland-dependent species rapidly losing habitat. They are Bluestem Prairie/Buffalo River State Park, Felton Prairie, Rothsay Prairie and Twin Valley/Neal Prairie. All are in northwestern Minnesota.