Date of Award

5-1994

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Arts (MA)

Department

Wildlife Ecology and Wildlife Conservation

Advisor

Ray B. Owen

Second Committee Member

Kate Beard

Third Committee Member

Malcolm L. Hunter, Jr.

Abstract

Following a long absence due to over-trapping, beaver (Castor canadensis) recolonized most of their continental range during the middle of the 20th century. The spread of beaver across the landscape was revealed by the emergence of beaver-created wetlands, or flowages. Based on the appearance of flowages on aerial photographs from 1939, 1957, 1974, and 1991, I documented the return of beaver to a 105 km^ watershed in south-central Maine. I sought to determine if certain wetland characteristics—area, perimeter to dam length (p/d) ratio, and watershed size—influenced the order in which sites were occupied by beaver. Also, to gauge the effect of beaver on the landscape, I measured the total area of flowages and the distance from each wetland to the nearest neighboring wetland at each time period. I also observed vegetational changes that occurred in flowages after they were inhabited by beaver.

Seventy-seven flowages were created between 1939 and 1991, which caused the median distance between wetlands to decrease 68%. The area, p/d ratio, and watershed size of new colony sites decreased each time period. By 1991,1.5% of the study area (160 ha) was affected by flooding by beaver. The vegetation of flowages underwent a general transformation from trees to herbs.

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