Thesis

Effect of Development on Mammal use of the Riparian Habitat Along the San Joaquin River

San Joaquin River riparian habitat has been subject to anthropogenic modifications such as housing development, golf courses, and gravel mining sites. These modifications can affect mammals, potentially causing extirpation, higher mortality, increased population sizes, and increased human contact. Mammal presence was investigated across a land development gradient in riparian habitats along 21.5km of the San Joaquin River. Trail cameras were placed for 396 days at six study sites and in three different vegetation densities within each site. The presence of mammal species at the different sites, different vegetation densities and different time periods was investigated, co-occurrence and overlap models applied to the data, and variation in biodiversity assessed across the development gradient. Mule deer (Odocoileus hemionus) and Coyote (Canis latrans) captures decreased with land development while Ground squirrel (Otospermophilus beecheyi), Gray fox (Urocyon cinereoargenteus), Red fox (Vulpes vulpes), Virginia opossum (Didelphis virginiana), Striped skunk (Mephitis mephitis), Brush Rabbit (Sylvilagus bachmani) and Bobcat (Lynx rufus) captures increased. Intra site biodiversity varied between vegetation densities. The positive or negative relationships of mammals with degrees of land development could have an impact in local species populations leading to species extirpation or species overabundance and perhaps increased human-wildlife conflict or the spread of zoonotic diseases.

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