BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofitpublishers, academic institutions, research libraries, and research funders in the common goal of maximizing access tocritical research.Habitat Partitioning by Sympatric Ocelots and Bobcats:Implications for Recovery of Ocelots in Southern TexasAuthor(s) :Jon S. Horne, Aaron M. Haines, Michael E. Tewes, and Linda L.LaackSource: The Southwestern Naturalist, 54(2):119-126. 2009.Published By: Southwestern Association of NaturalistsDOI:URL: http://www.bioone.org/doi/full/10.1894/PS-49.1BioOne (www.bioone.org) is a a nonprofit, online aggregation of core research in thebiological, ecological, and environmental sciences. BioOne provides a sustainableonline platform for over 170 journals and books published by nonprofit societies,associations, museums, institutions, and presses.Your use of this PDF, the BioOne Web site, and all posted and associated contentindicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use.Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should bedirected to the individual publisher as copyright holder.HABITAT PARTITIONING BY SYMPATRIC OCELOTS AND BOBCATS:IMPLICATIONS FOR RECOVERY OF OCELOTS IN SOUTHERN TEXASJON S. HORNE,* AARON M. HAINES,MICHAEL E. TEWES, AND LINDA L. LAACKFeline Research Center, Caesar Kleberg Wildlife Research Institute, Campus Box 218,Texas A&M University-Kingsville, Kingsville, TX 78363 ( JSH, MET)University of Idaho, Center for Research on Invasive Species and Small Populations, Moscow, ID 83844 (AMH)Environmental Defense Fund, 44 East Avenue, Suite 304, Austin, TX 78701 (LLL)Present address of JSH: Department of Fish and Wildlife Resources, University of Idaho, Moscow, ID 83844*Correspondent: [email protected]—Populations of ocelots (Leopardus pardalis) have declined during the past century duemainly to loss of habitat resulting in the ocelot being listed as endangered by the United States Fish andWildlife Service. In southern Texas, the northern distribution of the ocelot overlaps the southerndistribution of the bobcat (Lynx rufus). Because bobcats could adversely affect populations of ocelotsthrough interspecific competition, we examined habitat selection of sympatric ocelots and bobcats todetermine if habitat partitioning could be functioning to reduce interspecific interactions. Usingradiotelemetry, we analyzed macro-scale (vegetative communities) and micro-scale (structuralcomponents) selection of habitats by sympatric ocelots and bobcats on Laguna Atascosa NationalWildlife Refuge, Cameron County, Texas. We looked for differences in placement of home rangeswithin the general study area, selection of cover within home ranges, and use of structural componentsof vegetation within types of cover. There was substantial evidence for habitat partitioning with ocelotsselecting areas with .75% canopy cover, while bobcats selected areas with ,75% canopy cover. Thus,coexistence between these two species might be facilitated by resource partitioning of habitat.RESUMEN—Las poblaciones de ocelote (Leopardus pardalis) han disminuido durante el u´ltimo siglodebido principalmente a la pe´rdida de ha´bitat. Como resultado, esta especie ha sido enlistada enpeligro de extincio´n por el United States Fish and Wildlife Service. En el sur de Texas, la distribucio´nseptentrional del ocelote se sobrepone con la distribucio´n meridional del lince rojo (Lynx rufus).Debido a que el lince rojo podrı´a afectar negativamente las poblaciones del ocelote con la competenciainterespecı´fica, examinamos la seleccio´n de ha´bitat de las dos especies simpa´tricas para determinar si laparticio´n de ha´bitat podı´a reducir las interacciones interespecı´ficas. Usando radiotelemetrı´a,analizamos la seleccio´n de ha´bitat a una macro escala (comunidades vegetales) y a una micro escala(componentes estructurales) en Laguna Atascosa National Wildlife Refuge, condado de Cameron,Texas. Buscamos diferencias en la ubicacio´n de rangos de hogar dentro del a´rea general de estudio, laseleccio´ n del tipo de cobertura dentro del rango de hogar, y el uso de componentes estructurales devegetacio´ n dentro del tipo de cobertura. Encontramos evidencia substancial de la particio´n de ha´bitat,con ocelotes seleccionando a´reas con .75% de cobertura del dosel mientras que el lince rojoselecciono´a´reas con ,75% de cobertura del dosel. Por lo tanto, la particio´n de los recursos del ha´bitatpodrı´a facilitar la co-existencia entre estas dos especies.The ocelot (Leopardus pardalis) is one of therarest felids in the United States. Historically,populations in the United States ranged fromsouthern through eastern and central Texas towestern Louisiana and southern Arkansas(Woodward, 1980). Currently, distribution with-in the United States is limited primarily to thesouthern portion of Texas in Cameron andWillacy counties (Haines et al., 2006b); size ofthe population is estimated at 80–100 individuals(Tewes and Everett, 1986; Haines et al., 2006c).Loss of habitat is believed to be the main reasonfor reduction in range and decline in populationsof ocelots (Tewes and Everett, 1986), which hasled to the ocelot being listed as endangered by theUnited States Fish and Wildlife Service (1982).Ocelots and bobcats (Lynx rufus) are sympatricfrom southern Texas to southern MexicoTHE SOUTHWESTERN NATURALIST 54(2):119–126 JUNE 2009(Rolley, 1987; Tewes and Schmidly, 1987). Basedon competitive-exclusion theory (Gause, 1934),it is believed that ecologically equivalent speciescannot coexist (Schoener, 1974; Anderson et al.,2002; Rastetter and Agren, 2002). Therefore,recovery strategies for ocelots should include anunderstanding of the competitive relationshipbetween ocelots and bobcats. Rosenzweig (1966)stated that differences in size of carnivoresprovides a means for coexistence, and Schoener(1974) described three forms of ecologicalpartitioning including habitat, temporal, andfood that could allow for coexistence. However,ocelots and bobcats are similar in size (Sunquistand Sunquist, 2002), feed mostly on smallmammals and birds, and primarily are crepuscu-lar and nocturnal (Rolley, 1987; Tewes andSchmidly, 1987). Thus, differences in selectionof habitat may be the primary form of ecologicalpartitioning