1Habitat Partitioningof Sympatric Ocelot and Bobcat in Southern TexasJon S. Horneand Michael E. TewesBackground…Ocelot (Leopardus pardalis)♦ Inhabit areas with dense cover♦ Endangered1982 (USFW)Ocelot distributionOverlap with bobcat♦ Crepuscular and nocturnal activity♦ Prey: small mammals and birdsBackground... Bobcat (Lynx rufus)♦ Crepuscular and nocturnal ♦ Prey: small mammals and birds♦ Still abundant overmost of distribution♦ Inhabit areas with dense coverand high prey densitiesBobcat distributionOverlap with ocelot2Justification• Gause’s (1934) Competitive Exclusion Principle– ecological equivalents cannot stably coexistType of Partitioning* Current KnowledgeTemporal………………………both crepuscular/nocturnalFood type………………………>90 % overlap Habitat…………………………. ?* Described by Schoener (1982)Objectives• Determine if differences in habitat use could be detected where ocelots and bobcats co-occur– Macrohabitat: community scale vegetative associations– Microhabitat: structural components within communities• Relate any differences to differences in population status of ocelots and bobcatsStudy SiteLaguna AtascosaNational WildlifeRefugeCameron county3Methods…Habitat UseCat captureRadio telemetryMicrohabitatmeasurements• 4 Cover types*used by ocelots and bobcats– Closed, mixed, open, bare ground• Scale of Selection– Placement of home ranges within the study area– Selection of habitats within the home range• Selection Ratios– Compares proportion used to proportion available* Determined by relative canopy cover and major vegetative associationsMacrohabitat SelectionAre ocelots and bobcats using the same general cover types?4Microhabitat Use• 7 Structural Variables– Canopy height– Horizontal cover• Profiles: <1 m; >1 m; Total– Vertical cover• Profiles: <0.5 m; 0.5 m - 1 m; 1 - 2 mAre ocelots and bobcats using the similar vegetation structure within the same cover type?Results• Cat Capture– 10 ocelots (4 female and 6 male)– 8 bobcats (3 female and 5 male)• Telemetry– 191 locations (96 ocelot and 95 bobcat)• Habitat Separation– Significant differences at both macro and micro scalesPercent of Locations by Cover Type 11Closed90 %Open56 %Mixed31 %OcelotBobcatMixed9 %5Cover Type Separation…Home range placement compared to study area01234Selection ratio (90% C.I.)BobcatOcelotmixedclosed open Bare groundCover Type Separation…Use of cover types within the home range012345Closed Mixed Open Bare groundSelection ratio (90% C.I.)BobcatOcelotMicrohabitat Separation• Within the same cover type, ocelots used sites with:1. Higher canopies2. Greater canopy cover >1m3. More screening cover6Conclusions• Ocelots and bobcats used different habitats at both macro and micro-scales• Differences were related to vegetative cover >1 m– canopy height, horizontal cover >1 m, vertical cover 1 -2 m, woody debris• Habitat partitioning may serve to reduce interspecific competition between ocelots and bobcatsConclusions(continued)• Theories of Resource Partitioning– Partitioning may result from evolutionary adjustments– Partitioning may result independent of competitive pressure• Important Management Implications– <1 % of Southern Texas supports closed canopy thornshrub preferred by
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