Exploring relationships among recreation, habitat type, and Mexican spotted owls on the Colorado Plateau in Southern Utah
Hockenbary, Chad Evan
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The Mexican spotted owl (Strix occidentalis lucida) was listed as "threatened" in 1993 by the U.S. Fish and Wildlife Service. In Utah, the spotted owl is associated with rocky canyons that attract high levels of human recreation. Recreation could potentially have negative effects on the owl. I investigated roost behavior, territorial occupancy rates, and reproduction in canyon habitats that differed in recreation level and habitat condition (e.g., xeric versus mesic environments). Surveys were conducted in four areas in Utah: Zion and Capitol Reef National Parks, Grand Staircase-Escalante National Monument, and the Cedar Mesa-Elk Ridge highland. In Chapter 2, I evaluated possible differences in behaviors by fledglings across different levels of recreation. Fledgling diurnal behaviors were dependent on recreation level (P < 0.05). Fledglings in both recreation classes spent approximately = 50% of their time roosting, but fledglings associated with high-recreation territories spent more time in maintenance behaviors (13% vs. 4%) and less time in vigilant behaviors (29% vs. 35%) than did those in low-recreation territories. In Chapter 3, results from a top-ranked regression model indicated potential association between owl site occupancy rates and habitat type, with mesic sites showing higher occupancy than xeric sites in 2008: 0.75 (95% CI = 0.57 - 0.87) and 0.50 (95% CI = 0.27 - 0.73). Recolonization rate was 0.53 (95% CI = 0.28 - 0.76) for mesic sites and 0.10 (95% CI = 0.02 - 0.37) for xeric sites. Extinction rate was constant across years and sites (0.25; 95% CI = 0.15 - 0.39). Detection probability was 0.89 (95% CI = 0.82 - 0.94) across all three years of study. The number of fledglings per pair was greater in 2009 (0.94) than 2008 (0.25) and 2010 (0.50). My results suggest that recreation could have altered diurnal roost behavior of fledglings but was not related to occupancy and reproduction of Mexican spotted owls.