Problem/Background

Medicine Lake National Wildlife Refuge in Montana is home to one of the largest colonies of American white pelicans (Pelecanus erythrorhynchos) in the United States. White pelicans are considered a species of local management concern in Montana (MT Partners in Flight Conservation Plan 2000). This colony has been in existence since at least 1938, and numbers grew steadily with increased protection for the species (current 10-yr average = 3700 nests). The colony is located on two islands and a nearby peninsula on 8200-acre Medicine Lake. White pelicans are known to forage in shallow marshes, rivers, and lake edges, where mainly small fish and amphibians are taken, but relatively few studies have been done on this species, and none in Montana. Although the pelicans nest on the refuge, most foraging takes place off the refuge, as birds travel into surrounding private lands in the Northeast Montana Wetland Management District. Nothing is known about the pelicans' daily activities away from the breeding colony, such as what wetlands or streams are important foraging areas, what prey is taken, and how large an area the pelicans need to survive. Pelicans in some areas are known to commute over 50 miles to forage during the breeding season (Evans and Knopf 1993). Food is then brought back to the young and regurgitated. Some people who fish for sport in Montana worry that the pelicans may be reducing the number of fish available for fishing, and are putting pressure on wildlife managers to control the size of the pelican colonies. However, the Medicine Lake pelican colony makes up a large portion of the entire pelican breeding population in North America, and reducing the number of pelicans in this colony may have a negative effect on the entire breeding population of pelicans. In order to address these management and conservation concerns, it is critical for refuge managers to gather information on the ecology and activities of these birds. Because of the distances traveled by pelicans during the breeding season, satellite telemetry is the most cost-effective way to monitor these wide-ranging birds.

There is an even more serious threat to the pelicans’ survival occurring on their wintering grounds. The breeding population of white pelicans in Montana migrates each fall to wintering grounds in southern United States. On some of these wintering grounds, such as in Louisiana and Mississippi, white pelicans forage on fish farms, and the owners of the fish farms try to get rid of the pelicans using a variety of techniques, including killing the pelicans. In order to begin to resolve this conflict between the fish farmers and the pelicans, it is important to find out more about these wintering pelicans, such as what other habitats they are using on their wintering grounds, and where they migrate to during the breeding season. Satellite telemetry can allow scientists to track the pelicans during their migration, on their wintering grounds, and then back again to their breeding grounds, giving scientists a complete picture of the movements and habitat use of these birds.

Objectives and Methods
The purpose of this work is to determine the habitat use, home range, and foraging activities of American white pelicans nesting on Medicine Lake National Wildlife Refuge (NWR), in one of the largest breeding colonies of pelicans in the United States. Scientists from the Medicine Lake Wildlife Refuge, from Earthspan, and from St. Cloud State University are using satellite telemetry to track 5 pelicans for a one and a half-year period: through the breeding season, fall migration, on wintering grounds, and back to the breeding colony for another breeding season and fall migration. The five pelicans were tagged in July 2002 on their breeding grounds. The transmitters have a multi-season timer, allowing intensive collection of location data during the breeding season (approximately 8 hours/day providing about 6 locations), with less frequent locations collected during migration and the wintering season. Using the location data together with Geographic Information Systems (GIS), the scientists will be able to determine what type of habitat the pelicans use during the breeding season and how large an area they use. Migration and wintering areas will be mapped at a coarser scale.

In addition, most young pelicans in the colony are being fitted with numbered, aluminum leg bands on their breeding grounds to allow identification of individual pelicans. When and where any of these banded birds are found will help scientists to determine what proportion of the young pelicans return to the colony, how long they live, and what migration routes and wintering areas they use. Diet samples will be collected from chick (and adult where possible) regurgitate in the colony during early, mid, and late breeding season to describe food habits through the summer.

                            © Earthspan 2002