3:51 p.m. - Biologists are making elaborate plans to monitor and safeguard American white pelicans when they return to their long-time nesting grounds at Chase Lake National Wildlife Refuge, the same sites they mysteriously left last spring, abandoning nests and chicks.

Strategies the U.S. Fish and Wildlife Service plans to employ include restricting visitor access to the nesting areas, where up to 30,000 pelicans are expected later this month, and putting up a barrier fence to prevent predation by coyotes and foxes on the peninsula colony.

Also, biologists from the U.S. Geological Survey's Northern Prairie Wildlife Research Center in Jamestown will place satellite transmitters on 10 adult pelicans to track their movements and gather other data, but that won't be done until after the pelican eggs hatch.

USGS scientists also will conduct a companion study to a West Nile virus assessment that began in 2004. They will use surveillance cameras, binoculars and spotting scopes to observe the colony from a distance, minimizing human disturbance.

Scientists plan to use the data and observations to put together a management and conservation plan for American white pelicans. The USFWS announced the strategies Thursday.

So far, pelicans don't appear ready to leave their winter digs.

"We're not seeing high-flying flocks headed out yet," Ann Paul, Tampa Bay regional coordinator for Audubon of Florida, said by telephone Thursday. "About 250 pelicans were spotted on a lake last weekend, and there are more on (part of Tampa Bay)."

American white pelicans typically pull out of their coastal wintering grounds along the Gulf of Mexico between mid-March and the middle of April, Paul said.

The pelicans always are a popular viewing attraction for birders and others who appreciate wildlife, but this year, access routes to the nesting sites will be marked with warnings that say "area beyond this sign is closed." Anyone caught violating the restrictions could face a fine, said Ken Torkelson, a spokesman for the USFWS' Bismarck office.

In the past, pelican watchers could obtain an access permit from the refuge headquarters that allowed them to get close-up looks at the big, white, double-chinned birds.

The best pelican-viewing opportunities this summer will on wetlands anywhere around Chase Lake, said Torkelson. The refuge is north of Medina.

The pelicans' pullout last year began in late May and carried over into early June. An estimated 27,000 pelicans vanished, abandoning two of the three refuge nesting sites and thousands of eggs.

A third nesting site, located on a large island, continued to hold about 2,500 nests, and nesting activity there appeared to be progressing normally. However, a late June check of the island revealed that those nests, most with newly hatched young, also had been abandoned. None of the chicks survived.

Satellite tracking of four adult Chase Lake pelicans showed one bird moved to western South Dakota, another went to eastern South Dakota, a third to northern Minnesota and the fourth to north-central North Dakota.

What caused the exodus remains a mystery. The leading theories have centered around predator or human disturbance, wet and often cold weather, shortages of forage or disease. Investigations, however, did not lead to concrete answers.

The 10 adult pelicans to be tracked will be fitted with backpack-style transmitters that are about the size of a deck of playing cards and weigh about 2 1/2 ounces. Solar powered, the transmitters are expected to last for three years, Torkelson said.

Data from the transmitters will help scientists understand nest attendance, proportion of time spent away from the colony, distances traveled to foraging sites and their locations and characteristics.

Using 10 transmitters was a financial consideration, Torkelson said, explaining that they cost "in the neighborhood of $4,000 apiece." Data collection from the transmitters also costs money, Torkelson added.

"We feel we can get the information we need from that many transmitters," he said.

The fence the USFWS will install will be 540 feet long and 42 inches tall. It will be electric, and solar panels will provide the juice.

"Supposedly, one touch will be a learning process (for predators)," Torkelson said.

The fence is expected to go up within the next couple of weeks.

"The frost is pretty thick on the ground, and the lake is still iced over," Torkelson said. The budget for the fence is $1,500.

White pelicans are one of the largest birds in North America, measuring 6 feet from bill to tail and weighing up to 20 pounds. The wing-span can be 9 1/2 feet. Adult pelicans have a long orange bill with a pouch.

The Chase Lake nesting colony is believed to be the largest in North America. White pelicans have been nesting there for more than 100 years.

Biologists have monitored Chase Lake pelicans since 1905, when the birds numbered about 50. President Theodore Roosevelt designated the site as a national wildlife refuge in 1908, after many of the birds were being killed for their feathers and used for target practice.

Wildlife officials have been conducting annual aerial surveys of the pelicans since 1972, and their number has tripled at the refuge in the past 30 years. In 2000, scientists recorded an all-time high 35,466 breeding pelicans and 17,733 nests.

As for whether the pelicans will return sometime this month, Torkelson is a believer.

"There's no reason to believe they won't be back," he said.

(Reach reporter Richard Hinton at 250-8256 or outdoors@bismarcktribune.net.)