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The Effect of Habitat Fragmentation on Mammalian CarnivoresEPA Grant Number: U915245
Title: The Effect of Habitat Fragmentation on Mammalian Carnivores
Investigators: Crooks, Kevin R.
Institution: University of California - Santa Cruz
EPA Project Officer: Smith, Bernice
Project Period: January 1, 1997 through January 1, 2000
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1997) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Ecological Indicators/Assessment/Restoration , Fellowship - Ecology and Ecosystems
The objectives of this research project are to: (1) evaluate the effects of urban development and habitat fragmentation on the distribution, abundance, and conservation of mammalian carnivore species to produce statistical models that will help predict how the spatial organization (size and connectivity) of habitat fragments in an urban landscape affect carnivore population persistence; and (2) evaluate the top-down ecological effect of dominant mammalian carnivores in fragmented systems. I hypothesize that top predators (e.g., coyotes) will have a negative effect on "mesopredators" (e.g., domestic cats, foxes, skunks, opossums, and raccoons), and in turn, an indirect and positive effect on mesopredator prey species (e.g., scrub specialist bird species).
This research was conducted in San Diego County in patches of chaparral and sage scrub canyon habitat isolated at different times during the last century of urban development. Distribution, relative abundance, and visitation rates of carnivores were assessed through a combination of traditional methods and new techniques: (1) scat counts along transect lines; (2) DNA analysis of scat to provide species and individual identification; (3) track counts of animals attracted to scent lures; (4) remotely triggered cameras stationed along routes of travel; (5) radio-telemetry; and (6) questionnaires distributed to residents bordering natural areas. Target species included mountain lion, bobcat, coyote, gray fox, red fox, raccoon, striped skunk, spotted skunk, opossum, domestic dog, and domestic cat. With distribution and abundance data for each species, I could evaluate their relative sensitivities to habitat fragmentation measured at both a local and landscape scale. Furthermore, I could use variation in top predator distribution and abundance to assess their direct and indirect effects on community structure.