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Reilly ML. 2015. The effects of non-motorized recreation on mid-size and large mammals in the San Francisco Bay ecoregion. PhD Dissertation, Northern Arizona University. doi:10.13140/RG.2.1.2068.6168
Year Published: 2015

Large and medium-sized mammals play important roles as dominant herbivores and as top-down regulators. Because many carnivores and larger mammals are area-sensitive and cannot cross inappropriate habitat, these animals are ideal focal species for the design of wildlife corridors. Corridor planners and protected area managers in particular need answers to questions such as: Does non-motorized recreation compromise utility of corridors and protected area for these mammals? Is there a “safe distance” from trails that could inform where trails can be located in corridors?

Non-motorized recreation by humans, and associated domestic animals such as dogs and horses, can impact wildlife by disrupting normal maintenance routines, reducing feeding time, displacement from suitable habitat, increasing adrenal stress hormones, and provoking flight response. Although past research suggests recreation negatively impacts density and abundance of carnivore species, wildlife populations that have a long history of exposure to recreation may have become habituated. I assessed species-levels behavioral changes of 10 mid-size or large mammals to human recreation both spatially and temporally. Camera traps were used to collect data on wildlife presence and to quantify the amount of recreation in protected areas. First, I investigated how different levels of hiking, biking, equestrians, and domestic dog presence impact habitat used by a suite of species. Next, I investigated diel shifts in activity patterns of wildlife in areas with no recreation compared to areas with any recreation and high levels of human recreation. Finally, I investigated weekday and weekend activity levels of recreation and wildlife.

To leverage public support, conservationists typically want to allow recreation in protected areas such as parks, reserves, and wildlife corridors. Thus, limiting outdoor recreation in protected areas may decrease public support for land and wildlife conservation. The matrix of protected natural areas throughout the San Francisco Bay ecoregion supports a diverse community of wildlife species. Conservation of areas relatively free of negative impacts, connected by wildlife corridors, is a priority for millions of Bay Area residents. These same residents enjoy walking and biking in these parks and corridors. Our results indicate that species differ in their response to non-motorized human recreation. A handful of species showed aversion to certain types of human recreation and exhibited spatial avoidance of sites with recreation while other species shifted their diel activity patterns to avoid contact with recreation; still others had no negative temporal or spatial response to recreation. Species may have adapted or already responded to the long history of recreation in protected areas in the SF Bay area. For the species included in our analysis and that are impacted, none are identified as sensitive, threatened, or endangered. It is therefore my stance that the impacts are small in relation to the multiple gains such as human health benefits and continued political and financial support for land and species conservation. Most species included in our analysis are widely distributed across the San Francisco Bay ecoregion further suggesting that these species exhibit plasticity and adaptability. link to publication