Sullys Hill National Game Preserve
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Project Background
Sully's Hill National Game Preserve (SHNGP) is a 1,675 acre preserve where extirpated Rocky Mountain elk (Cervus elaphus), Plains bison (Bison bison), and white-tailed deer (Odocoileus virginianus) were re-introduced. These large ecosystem engineers have been managed at varying densities within a fenced area of deciduous woods and native prairie since 1915. Grazing, browsing, and rubbing by ungulates, along with additional refuge management prescriptions (e.g. fire), shape the understory and midstory and in turn determine which birds will nest and forage in the area.
The 2008 SHNGP Comprehensive Conservation Plan recommended a 50% reduction in herd sizes based on vegetation surveys which indicated overbrowsing and overgrazing. A maximum ungulate density of 0.12 animals per acre was reduced to about 0.07 animals per acre and has been annually maintained since 2008.The primary objective of this study was to re-evaluate the songbird community to determine if large ungulate reduction has improved forest health with a subsequent increase in bird abundance and diversity. Results of bird surveys conducted in 2004 will be used as a baseline for comparison with 2012-2013 surveys. Ten minute point count surveys at 57 locations will be conducted across SHNGP to evaluate target bird species of ovenbirds (Seiurus aurocapilla), red-eyed vireos (Vireo olivaceus), and American redstart (Setophaga ruticilla) for changes in population before and after the herd reduction treatment. Ovenbirds forage and nest in forest understory; American redstarts forage and nest in the forest midstory; red-eyed vireos forage and nest in forest midstory and canopy. If a decrease in ungulate size decreases browsing and grazing, we hypothesize that there will be an increase in vegetation at one or more layers with a subsequent increase in the target species of that layer.
Forest vegetation surveys of understory, midstory, and canopy will be conducted in 2012-2013 to determine if changes in forest health and composition occurred since 2005 in response to the herd reduction and to verify this as a possible mechanism driving any changes in target bird species populations.
Project Collaborators
- Beth Walters - M.S. Student, UND Biology Department
- Mark Fisher - Wildlife Biologist, U.S. Fish and Wildlife Service