Use of Exclosures to Protect Small Ground-nesting Birds
GARY N. CORBETT
Canadian Parks Service, Upper Water Street, Halifax, NS
B3H 1S9 Canada
There are seven National Parks in Canada's four Atlantic provinces (New Brunswick, Nova Scotia, Prince Edward Island, and Newfoundland). Three of these parks have summer resident breeding populations of piping plovers (Charadrius melodus). They are the seaside adjunct to Kejimkujik National Park, Prince Edward Island National Park, and Kouchibougnac National Park. During the early 1970s, over 65 pairs of piping plovers nested on light colored sand beaches in those three parks. Since that time, the species has declined across Canada and is now designated an endangered species. By 1989, the number of piping plover nesting in national parks of Atlanic Canada had declined to 42 pairs.
Since 1985, the piping plover has been extensively studied and managed in the national parks. Productivity has varied greatly due to human disturbance, storm flooding, and predation; major factors affecting nesting success. Egg predation alone was responsible for annual losses of up to 85 % of egg production in some areas. Nest predators included red fox, raccoon, gulls, and American crows.
In an effort to reduce or eliminate nest predation, wire fence exclosures of 2x2-inch and 2x4-inch mesh have been placed over piping plover nests since 1988. As of July 1990, over 70 nest have been fenced and over 80% of the fenced nests hatched young. No fenced nests have been depredated after the program began. Exclosed nest losses have been from abandonment, sand covering, and vandalism. Other management practices accompanying use of exclosures included closure of nest areas to public use, extensive surveillance, and limited raccoon trapping in one park.
Through the use of exclosures and other management practices the number of young fledged per breeding pair of piping plover increased from a low of 0.4 (1985, 1 park) and a mean of 1.2 for all three parks (1986-88) to a mean of 2.1 for all three parks in 1989. As of 23 July 1990, surveys indicate a probable fledging rate of over 2.0 young per pair for all three parks. Although more years of study will be necessary, it appears that exclosures play an important role in the management of this endangered species.
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