Defining Habitat for the Recovery of Ocelots (Leopardus pardalis) in the United States
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The ocelot (Leopardus pardalis) was placed on the United States federal endangered species list in 1982. Historically these felids were hunted for their pelts, but other factors have contributed over the years to their placement on the list. Today, the major factor that causes ocelots to be endangered is loss of habitat. Previous research has demonstrated that ocelots prefer habitats of dense shrubs with greater than 95% canopy cover. However, little else is known about the total composition of vegetation in their habitat. The objectives of our study were to develop a geographic information system (GIS) containing vegetation, soil and satellite imagery for seven counties (Willacy, Cameron (Laguna Atascosa National Wildlife Refuge), Starr, Hidalgo, Jim Hogg, Kenedy, and Zapata) in South Texas to enhance prior research and define areas suitable to support ocelots. Ground-truthing on vegetation transects on public and private land across these counties was performed using a densiometer, vegetation profile board (VPB), and Daubenmire frame techniques to determine key vegetative characteristics that comprise ocelot habitat. Through principal components analysis (PCA), we analyzed slope and intercept (VPB measures), percent canopy cover (overstory), percent grass, litter, bare ground, and forbs from Daubenmire frames, woody species richness, woody plant density, woody plant diversity, and average woody plant height per transect. We found the majority of ocelot habitat was characterized by greater plant diversity, greater vertical cover density at ground level, greater canopy cover, smaller shrubs, and more ground litter than habitat not occupied by ocelots. Along an east-west gradient in South Texas, eastern sites were more similar to ocelot habitat. Comprehensive vegetation information (i.e. plant density, percent grass, etc.) is lacking on satellite/ land-use images. Therefore, comparing habitat data through PCA analysis would be more effective in delineating ocelot habitat.