Thursday, April 19, 2007

The Trumpeter Swan in Michigan

The Michigan Department of Natural Resources briefly described the historical status of the Trumpeter Swan in this undated document (excerpt):
Historically, trumpeter swans were most likely abundant throughout the Great Lakes region, even in the southern Michigan marshlands. On his travels along the Detroit River in 1701, Cadillac compared the abundance of swans to lilies among the rushes.
That broad-brush characterization seems at odds with this statement by Woods (1951) regarding its known occurrence in Michigan:
One authentic specimen: a male (U.S.N.M.), taken November 20, 1875, by W. H. Collins, at the St. Clair Flats, St. Clair County (Stejneger, 1882:218). [from digitized text provided here]
Regardless of what their true historic status in Michigan might have been, the DNR embarked on an ambitious program to “reintroduce” trumpeter swans to the State, as described here (excerpt):
During the 1980s, Michigan began a swan reintroduction program as part of the North American Restoration Plan. The Michigan commitment to the plan was establishment of three self-sustaining populations in Michigan of at least 200 swans by the year 2000. Early attempts at cross-fostering trumpeter eggs with mute swans provided low success rates and were abandoned.

The second phase involved rearing of cygnets for two years prior to releasing them into prime wetland habitat. Eggs were collected from zoos and incubated to hatching. The rearing approach proved much more successful. Additionally, in 1989, biologists from the DNR and Kellogg Bird Sanctuary traveled to Alaska to collect eggs from wild populations to include in the rearing program.

To raise awareness of the program, the Natural Heritage Program highlighted the trumpeter swan on the Living Resources patch, T-shirt, and print, produced in 1990-1991. After nearly 15 years, the Program can be claimed a complete success: the 2000 count of trumpeter swans in Michigan exceeded 400 individuals.

The 2000 population census identified three distinct population areas. The first included southwest Michigan with over 100 birds. The second population was found in the four-county region of Oscoda, Alcona, Ogemaw, and Iosco. At least 50 swans were found in this area. The most likely place to see trumpeter swans in Michigan is Schoolcraft County in the central Upper Peninsula. Seney National Wildlife Refuge had a total of 191 birds with 18 pairs nesting on the area. Seney, as well as a couple other sites in Schoolcraft County, harbors over 50 percent of the trumpeters known in Michigan.
This is just one of many classic examples in which it sometimes becomes difficult to distinguish the reintroduction and restoration of a population from the introduction of a species into an area where it may never have nested historically.

Citations:

Michigan Department of Natural Resources. No date. Trumpeter Swan (Cygnus buccinator). Available here.

Wood, Norman A. 1951. The birds of Michigan. University of Michigan Miscellaneous Publication 75.

Labels: ,

Links to this post:

Create a Link

<< Home