Background

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Davis, T. 1986. St. Louis River Estuary Colonial Bird Program 1986. Report submitted to the Minnesota Department of Natural Resources. 16 pp.

Background:

During the past four years the Minnesota Department of Natural Resources has been involved in the development and implementation of a Colonial Bird Management Program for the St. Louis River estuary. The purpose of the program is to provide adequate, protected, long-term nesting sites for two species - the Common Tern and Piping Plover. This effort has been a cooperative effort of the Departments of Natural Resources in Minnesota and Wisconsin (MDNR and WDNR).

Concern for the terns and plovers, and thus the impetus for the program, stems from their precarious statewide and national status and the fact that they have experienced very poor nesting success the past several years in the estuary. The tern has an official status of Special Concern in Minnesota and is considered Endangered in Wisconsin. In addition, it is classified as a species of Special Emphasis in U.S. Fish and Wildlife Region 3 (Regional Resource Plan, USFWS 1983). The plover has an official status as Endangered in both states and this past year was designated a federally Endangered species in the U.S. Great Lakes by the U.S. Department of Interior.

For these reasons, a management program to perpetuate the nesting populations of these species in the St. Louis River estuary was proposed in 1977. This program has focused on providing secure nesting habitat since this appeared to be the primary problem. The emphasis has been on developing and maintaining nesting habitat on three islands (Hearding, Barkers, and Interstate) which lie in the lower estuary and close to the most recent nesting area used by both species - the Duluth Port Terminal property. Hearding Island lies in Minnesota waters, Barkers in Wisconsin, and Interstate astride the state line and thus in both states. Due to the locations with respect to state lines, Minnesota was assumed management responsibility for Hearding Island, Wisconsin for Barkers Island, and both states jointly for Interstate Island.

All three islands are man-made and were created during the early 1900's as harbor sediments dredged to deepen shipping channels were deposited in various areas within the harbor. The resulting islands, offering broad, sandy beach habitat, constituted ideal nesting sites for the Common Tern and Piping Plover. Both Hearding Island and Barkers Island have a documented history as major tern and plover nesting areas. However, due to the encroachment of vegetation including trees and shrubs, the islands eventually proved unsuitable as nesting sites. Prior to the implementation of this management program, neither terns nor plovers had been known to nest on the islands since the early 1960's.

Thus management of the islands has focused on removal of vegetation from portions of each in order to recreate the habitat which was attractive to the birds in earlier years. Eight acres were cleared on Barkers Island in 1981 while approximately 13 acres were cleared on Hearding Island in 1983 and nearly all of Interstate Island (8 acres) in 1984. In 1985, another acre of trees was removed from Interstate Island due to use by a Great Horned Owl. This left only a few scattered trees and brush on the island and these were removed prior to the 1986 nesting season. These areas have been designated Wildlife Management Areas and trespass prohibited during the nesting season.

In addition to creating suitable nesting habitat for the target species, the management program has also included elements to more actively encourage the birds to nest on the islands. This has involved placing tern decoys and playing tapes of tern calls on the islands during the arrival and courtship stages. These attraction techniques have been used on Hearding and Barkers Islands since 1983 and Interstate Island beginning in 1985.

The past two years on further management tool was added to the Port Terminal and Erie Pier nesting sites. Reproductive success at both sites has been extremely poor for several years. Preventing the terns from nesting in these areas could not significantly lower success further but could increase the chances that the terns successfully establish themselves and fledge young on the island management areas. Use of the Sky Harbor Airport site was also discouraged for the same reasons in 1986.

The above efforts have met some success in the past. In particular, during 1985, approximately 100 terns nested on Interstate Island and four terns on Hearding Island. Although no young fledged, the fact that the major portion of the tern population nested on the islands was a major breakthrough.

This report summarizes work done as part of the St. Louis River Estuary Colonial Bird Management Program during the 1986 nesting season. The work was done by this investigator under contract with the MDNR, Nongame Wildlife Program. During the early portions of the work, two field assistants were provided, one each by the MDNR and WDNR. Since Barkers Island is an integral part of this program and work on the island was coordinated with WDNR personnel, information pertaining to this site are included in this report.

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