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Michael E Tewes - One of the best experts on this subject based on the ideXlab platform.
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Spatial structure of woody cover affects habitat use patterns of Ocelots in Texas
Mammal Research, 2020Co-Authors: Jason V. Lombardi, Michael E Tewes, Humberto L. Perotto-baldivieso, Jose M. Mata, Tyler A. CampbellAbstract:About 80% of the known breeding population of Ocelots ( Leopardus pardalis ) in the USA occurs exclusively on private ranches in northern Willacy and Kenedy counties in South Texas. These private ranches support several large contiguous undisturbed patches of thornscrub, which is preferred by Ocelots. Past studies have indicated Ocelots in South Texas select for woody patches that contain extremely dense thornscrub (i.e., 95% canopy cover and 85% vertical cover) and require large patches of woody cover to survive. Landscape metrics have been used to explain Ocelot habitat use in fragmented areas, but their application in less-fragmented rangelands is lacking. From 2011 to 2018, we used camera traps on the East Foundation’s El Sauz Ranch to assess seasonal habitat use of Ocelots relative to landscape structure, configuration, and complexity and other site-level factors in South Texas. Seasonal habitat use and detection were positively influenced by larger mean patch area and lower landscape shape index values. We also observed Ocelots were less likely to be detected during periods of drought and exhibited a seasonal trend in detection. Ocelots used woody patches that were larger and more regularly shaped, indicating a preference for areas with a lower degree of fragmentation across the study area. As patches become larger, they will coalesce over time and form larger woody aggregates, which will promote Ocelot habitat use. Brush management needs to be strategic as patch area and shape index are a limiting factor to promote Ocelot habitat use on working rangelands in South Texas. These results demonstrate the ability to use landscape metrics to discern the effects of spatial structure of vegetation communities relative to Ocelot occupancy parameters.
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Effects of sun angle, lunar illumination, and diurnal temperature on temporal movement rates of sympatric Ocelots and bobcats in South Texas.
PLOS ONE, 2020Co-Authors: John P. Leonard, Michael E Tewes, Jason V. Lombardi, David W. Wester, Tyler A. CampbellAbstract:: Sympatric Ocelots (Leopardus pardalis) and bobcats (Lynx rufus) in South Texas show substantial overlap in body size, food habits, and habitat use. Consequently, we explore whether temporal niche partitioning may explain Ocelot and bobcat coexistence. We investigated the influence of sun angle, lunar illumination, and maximum diurnal temperature on temporal movement rates of sympatric Ocelots (n = 8) and bobcats (n = 6) using a combination of high-frequency GPS locations and bi-axial accelerometer data. We demonstrated that accelerometer data could be used to predict movement rates, providing a nearly continuous measure of animal activity and supplementing GPS locations. Ocelots showed a strong nocturnal activity pattern with the highest movement rates at night whereas bobcats showed a crepuscular activity pattern with the highest movement rates occurring around sunrise and sunset. Although bobcat activity levels were lower during the day, bobcat diurnal activity was higher than Ocelot diurnal activity. During warmer months, bobcats were more active on nights with high levels of lunar illumination. In contrast, Ocelots showed the highest nocturnal activity levels during periods of low lunar illumination. Ocelots showed reduced diurnal activity on hotter days. Our results indicate that Ocelot and bobcat coexistence in South Texas can be partially explained by temporal niche partitioning, although both felids showed periods of overlapping activity during nocturnal and crepuscular periods.
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Co-occurrence of bobcats, coyotes, and Ocelots in Texas.
Ecology and Evolution, 2020Co-Authors: Jason V. Lombardi, Michael E Tewes, Humberto L. Perotto-baldivieso, Jose M. Mata, Darryl I. Mackenzie, Tyler A. CampbellAbstract:Interspecific competition among carnivores has been linked to differences in behavior, morphology, and resource use. Insights into these interactions can enhance understanding of local ecological processes that can have impacts on the recovery of endangered species, such as the Ocelot (Leopardus pardalis). Ocelots, bobcats (Lynx rufus), and coyotes (Canis latrans) share a small geographic range overlap from South Texas to south-central Mexico but relationships among the three are poorly understood. From May 2011 to March 2018, we conducted a camera trap study to examine co-occurrence patterns among Ocelots, bobcats, and coyotes on the East Foundation's El Sauz Ranch in South Texas. We used a novel multiseason extension to multispecies occupancy models with ≥2 interacting species to conduct an exploratory analysis to examine interspecific interactions and examine the potential effects of patch-level and landscape-level metrics relative to the occurrence of these carnivores. We found strong evidence of seasonal mutual coexistence among all three species and observed a species-specific seasonal trend in detection. Seasonal coexistence patterns were also explained by increasing distance from a high-speed roadway. However, these results have important ecological implications for planning Ocelot recovery in the rangelands of South Texas. This study suggests a coexistence among Ocelots, bobcats, and coyotes under the environmental conditions on the El Sauz Ranch. Further research would provide a better understanding of the ecological mechanisms that facilitate coexistence within this community. As road networks in the region expand over the next few decades, large private working ranches will be needed to provide important habitat for Ocelots and other carnivore species.
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genetic differences in the response to landscape fragmentation by a habitat generalist the bobcat and a habitat specialist the Ocelot
Conservation Genetics, 2016Co-Authors: Jan E. Janecka, Aaron M. Haines, Michael E Tewes, Imogene A Davis, Arturo Caso, Terry L Blankenship, Rodney L HoneycuttAbstract:The ecology of a species strongly influences genetic variation and population structure. This interaction has important conservation implications because taxa with low dispersal capability and inability to use different habitats are more susceptible to anthropogenic stressors. Ocelots (Leopardus pardalis albescens) and bobcats (Lynx rufus texensis) are sympatric in Texas and northeastern Mexico; however, their ecology and conservation status are markedly different. We used 10 microsatellite loci and a 397-bp segment of the mitochondrial control region to examine how historical and ecological differences in these two species have influenced current patterns of genetic diversity in a landscape heavily altered by anthropogenic activities. Substantially higher genetic diversity (heterozygosity and haplotype diversity) and population connectivity was observed for bobcats in comparison to Ocelots. The level of divergence among proximate Ocelot populations ( 100 km. Ocelot populations in the US have never recovered from reductions experienced during the twentieth century, and their low genetic variation and substantial isolation are exacerbated by strong preference for dense native thornshrub and avoidance of open habitat. In contrast, despite continued legal harvesting and frequent road-related mortality, bobcats have maintained wide distribution, high abundance, and population connectivity. Our study illustrates that sympatric species with a similar niche can still have sufficient ecological differences to alter their response to anthropogenic change. Sensitive species, such as the Ocelot, require additional conservation actions to sustain populations. Ecological differences among species occupying a similar guild are important to consider when developing conservation plans.
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SURVIVAL AND SOURCES OF MORTALITY IN OcelotS
Journal of Wildlife Management, 2012Co-Authors: Aaron M. Haines, Michael E Tewes, Linda L. LaackAbstract:Abstract Survival and cause-specific mortality estimates are needed to develop effective conservation strategies for the endangered Ocelot (Leopardus pardalis) in the United States. We radiomonitored 80 Ocelots (36 F, 44 M) from 1983 to 2002 and analyzed survival and cause-specific mortality rates. Pooled estimates of annual survival rates differed between resident (Ŝ = 0.87) and transient (Ŝ = 0.57) Ocelots (P = 0.02); therefore, survival and cause-specific mortality analyses were partitioned for resident and transient Ocelots. Sex-specific annual survival was similar between resident Ocelots (M = 0.92, F = 0.83, P = 0.16) and transient Ocelots (M = 0.53, F = 0.63, P = 0.75). Most mortalities were from human (e.g., Ocelot–vehicle collisions; M = 45%) and natural (e.g., animal attack, disease; M = 35%) sources. Transient Ocelots had higher natural mortality rates (disease, intraspecific mortality; M = 0.26) than resident Ocelots (M = 0.04, P = 0.03). Other sources of mortality did not differ (P ≥ 0.10) be...
Jan E. Janecka - One of the best experts on this subject based on the ideXlab platform.
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genetic differences in the response to landscape fragmentation by a habitat generalist the bobcat and a habitat specialist the Ocelot
Conservation Genetics, 2016Co-Authors: Jan E. Janecka, Aaron M. Haines, Michael E Tewes, Imogene A Davis, Arturo Caso, Terry L Blankenship, Rodney L HoneycuttAbstract:The ecology of a species strongly influences genetic variation and population structure. This interaction has important conservation implications because taxa with low dispersal capability and inability to use different habitats are more susceptible to anthropogenic stressors. Ocelots (Leopardus pardalis albescens) and bobcats (Lynx rufus texensis) are sympatric in Texas and northeastern Mexico; however, their ecology and conservation status are markedly different. We used 10 microsatellite loci and a 397-bp segment of the mitochondrial control region to examine how historical and ecological differences in these two species have influenced current patterns of genetic diversity in a landscape heavily altered by anthropogenic activities. Substantially higher genetic diversity (heterozygosity and haplotype diversity) and population connectivity was observed for bobcats in comparison to Ocelots. The level of divergence among proximate Ocelot populations ( 100 km. Ocelot populations in the US have never recovered from reductions experienced during the twentieth century, and their low genetic variation and substantial isolation are exacerbated by strong preference for dense native thornshrub and avoidance of open habitat. In contrast, despite continued legal harvesting and frequent road-related mortality, bobcats have maintained wide distribution, high abundance, and population connectivity. Our study illustrates that sympatric species with a similar niche can still have sufficient ecological differences to alter their response to anthropogenic change. Sensitive species, such as the Ocelot, require additional conservation actions to sustain populations. Ecological differences among species occupying a similar guild are important to consider when developing conservation plans.
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socio spatial organization and kin structure in Ocelots from integration of camera trapping and noninvasive genetics
Journal of Mammalogy, 2015Co-Authors: Torrey W Rodgers, Jan E. Janecka, Patrick A. Jansen, Jacalyn Giacalone, Christopher A. Phillips, Edward J Heske, Robert L SchooleyAbstract:Kin selection theory predicts that under certain conditions animals will tolerate related individuals in their home ranges. We examined the relationship between spatiotemporal overlap and genetic relatedness in Ocelots (Leopardus pardalis) to determine if kin selection plays a role in structuring Ocelot populations. We used 3 years of camera trapping to examine the spatial organization of an Ocelot population on Barro Colorado Island in Panama. We also placed camera traps on Ocelot latrines to match photographs of individual Ocelots with microsatellite genotypes from feces. Strengths of spatiotemporal overlap between individual Ocelots were calculated using a half-weight association index based on how often individuals were photographed at the same camera within 30 days of one another. We calculated relatedness between individuals based on 11 variable microsatellite loci. Male Ocelots overlapped with ≤ 11 females, and females overlapped with ≤ 7 males. We detected no clear evidence of strict intersexual territoriality in either sex. Mean overlap among males was more than 5 times greater than overlap among females; however, spatiotemporal overlap was strong between some female pairs. Overall, overlapping individuals were more related to one another than was the sample population as a whole, consistent with the hypothesis that kin selection influences Ocelot spatial organization. This finding was driven by relatedness among overlapping females, and by relatedness among overlapping individuals of opposite sex, but not by overlapping males.
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comparison of noninvasive genetics and camera trapping for estimating population density of Ocelots leopardus pardalis on barro colorado island panama
Tropical Conservation Science, 2014Co-Authors: Torrey W Rodgers, Jan E. Janecka, Jacalyn Giacalone, Christopher A. Phillips, Edward J Heske, Robert L SchooleyAbstract:Estimates of population density are essential for the effective conservation and management of any threatened species. Accurately estimating density of elusive carnivores can be a challenge, however. One approach to this challenge is integration of DNA collected noninvasively from feces with capture-recapture modeling. To date, the bias and precision of this technique have seldom been evaluated in the field. We compared density estimates of Ocelots (Leopardus pardalis) derived from fecal noninvasive genetic techniques to density estimates from camera trapping in the same population, during the same study period. Density estimates from the two techniques were comparable, especially when using spatially explicit capture-recapture models. Population density estimated using the program DENSITY was 1.74/km2 (SE = 0.584) from noninvasive genetics and 1.59/km2 (SE = 0.464) from camera trapping. These estimates also represent the highest reported Ocelot population density within the species range.
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reduced genetic diversity and isolation of remnant Ocelot populations occupying a severely fragmented landscape in southern texas
Animal Conservation, 2011Co-Authors: Aaron M. Haines, Lon I. Grassman, Jan E. Janecka, Michael E Tewes, Linda L. Laack, D B Shindle, Arturo Caso, Brian W DavisAbstract:The Ocelot Leopardus pardalis has become a conservation priority in the US as a result of severe population decline and loss of habitat during the 20th century. Only two small populations remain in this country. Their short-term viability is threatened by the disappearance of dense thornshrub communities, human-caused mortality and demographic stochasticity. The influence these factors have on Ocelot persistence must be considered to develop effective conservation initiatives. We therefore examined neutral genetic diversity and connectivity among Ocelots in the US and northeastern Mexico using 25 autosomal microsatellites and a 395-bp segment of the mitochondrial control region. Genetic variation was lowest in the population occurring on Laguna Atascosa National Wildlife Refuge, Texas (autosomal microsatellite HE = 0.399 and mtDNA-haplotype diversity = 0) and highest in northeastern Mexico (0.637 and 0.73, respectively), while intermediate on private lands in Willacy County, Texas (0.553 and 0.252, respectively). Significant genetic differentiation between the two Texas populations was observed, despite their close proximity (� 30 km). Both populations were also significantly divergent from northeastern Mexico. The absence of any detectable gene flow implies that the human modified landscape of the Lower Rio Grande Valley in southern Texas acts as a strong barrier to Ocelot movement, disrupting metapopulation dynamics and contributing to loss of diversity. As a consequence, continued genetic erosion among the Texas populations is expected. The lack of movement through the fragmented landscape also suggests it is unlikely Ocelots will recolonize unoccupied habitat patches along the Lower Rio Grande and the delta interior where agriculture and urban land uses predominate. The continued rapid development will exacerbate this problem. These factors threaten the persistence of the Texas populations and limit their recovery. Translocations are necessary to link Ocelot populations in the US.
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phylogenetic relationships of Ocelot leopardus pardalis albescens populations from the tamaulipan biotic province and implications for recovery
Southwestern Naturalist, 2007Co-Authors: Jan E. Janecka, Michael E Tewes, Arturo Caso, Christopher W Walker, Linda L Laackand, Rodney L HoneycuttAbstract:Abstract The remaining populations of Ocelot (Leopardus pardalis albescens) in the United States are reduced to 2 isolated populations in southern Texas, with the next closest populations occurring in central Tamaulipas, Mexico. The species is listed as endangered, and recovery of populations in Texas eventually might require translocations from larger source populations. We sequenced the mitochondrial DNA control region from individuals from Texas and northern Mexico and compared these data to existing sequences derived from Ocelots in other parts of its range in southern Mexico, Central America, and South America. Nucleotide diversity was lower in Texas than in Mexico, suggesting a loss of genetic variation as a consequence of fragmentation and increased genetic drift. Phylogenetic analyses showed a close relationship between populations in Texas and northern Mexico that encompass the range of the subspecies L. pardalis albescens. Based on these data, the best source population for a recovery plan invol...
Aaron M. Haines - One of the best experts on this subject based on the ideXlab platform.
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genetic differences in the response to landscape fragmentation by a habitat generalist the bobcat and a habitat specialist the Ocelot
Conservation Genetics, 2016Co-Authors: Jan E. Janecka, Aaron M. Haines, Michael E Tewes, Imogene A Davis, Arturo Caso, Terry L Blankenship, Rodney L HoneycuttAbstract:The ecology of a species strongly influences genetic variation and population structure. This interaction has important conservation implications because taxa with low dispersal capability and inability to use different habitats are more susceptible to anthropogenic stressors. Ocelots (Leopardus pardalis albescens) and bobcats (Lynx rufus texensis) are sympatric in Texas and northeastern Mexico; however, their ecology and conservation status are markedly different. We used 10 microsatellite loci and a 397-bp segment of the mitochondrial control region to examine how historical and ecological differences in these two species have influenced current patterns of genetic diversity in a landscape heavily altered by anthropogenic activities. Substantially higher genetic diversity (heterozygosity and haplotype diversity) and population connectivity was observed for bobcats in comparison to Ocelots. The level of divergence among proximate Ocelot populations ( 100 km. Ocelot populations in the US have never recovered from reductions experienced during the twentieth century, and their low genetic variation and substantial isolation are exacerbated by strong preference for dense native thornshrub and avoidance of open habitat. In contrast, despite continued legal harvesting and frequent road-related mortality, bobcats have maintained wide distribution, high abundance, and population connectivity. Our study illustrates that sympatric species with a similar niche can still have sufficient ecological differences to alter their response to anthropogenic change. Sensitive species, such as the Ocelot, require additional conservation actions to sustain populations. Ecological differences among species occupying a similar guild are important to consider when developing conservation plans.
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SURVIVAL AND SOURCES OF MORTALITY IN OcelotS
Journal of Wildlife Management, 2012Co-Authors: Aaron M. Haines, Michael E Tewes, Linda L. LaackAbstract:Abstract Survival and cause-specific mortality estimates are needed to develop effective conservation strategies for the endangered Ocelot (Leopardus pardalis) in the United States. We radiomonitored 80 Ocelots (36 F, 44 M) from 1983 to 2002 and analyzed survival and cause-specific mortality rates. Pooled estimates of annual survival rates differed between resident (Ŝ = 0.87) and transient (Ŝ = 0.57) Ocelots (P = 0.02); therefore, survival and cause-specific mortality analyses were partitioned for resident and transient Ocelots. Sex-specific annual survival was similar between resident Ocelots (M = 0.92, F = 0.83, P = 0.16) and transient Ocelots (M = 0.53, F = 0.63, P = 0.75). Most mortalities were from human (e.g., Ocelot–vehicle collisions; M = 45%) and natural (e.g., animal attack, disease; M = 35%) sources. Transient Ocelots had higher natural mortality rates (disease, intraspecific mortality; M = 0.26) than resident Ocelots (M = 0.04, P = 0.03). Other sources of mortality did not differ (P ≥ 0.10) be...
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reduced genetic diversity and isolation of remnant Ocelot populations occupying a severely fragmented landscape in southern texas
Animal Conservation, 2011Co-Authors: Aaron M. Haines, Lon I. Grassman, Jan E. Janecka, Michael E Tewes, Linda L. Laack, D B Shindle, Arturo Caso, Brian W DavisAbstract:The Ocelot Leopardus pardalis has become a conservation priority in the US as a result of severe population decline and loss of habitat during the 20th century. Only two small populations remain in this country. Their short-term viability is threatened by the disappearance of dense thornshrub communities, human-caused mortality and demographic stochasticity. The influence these factors have on Ocelot persistence must be considered to develop effective conservation initiatives. We therefore examined neutral genetic diversity and connectivity among Ocelots in the US and northeastern Mexico using 25 autosomal microsatellites and a 395-bp segment of the mitochondrial control region. Genetic variation was lowest in the population occurring on Laguna Atascosa National Wildlife Refuge, Texas (autosomal microsatellite HE = 0.399 and mtDNA-haplotype diversity = 0) and highest in northeastern Mexico (0.637 and 0.73, respectively), while intermediate on private lands in Willacy County, Texas (0.553 and 0.252, respectively). Significant genetic differentiation between the two Texas populations was observed, despite their close proximity (� 30 km). Both populations were also significantly divergent from northeastern Mexico. The absence of any detectable gene flow implies that the human modified landscape of the Lower Rio Grande Valley in southern Texas acts as a strong barrier to Ocelot movement, disrupting metapopulation dynamics and contributing to loss of diversity. As a consequence, continued genetic erosion among the Texas populations is expected. The lack of movement through the fragmented landscape also suggests it is unlikely Ocelots will recolonize unoccupied habitat patches along the Lower Rio Grande and the delta interior where agriculture and urban land uses predominate. The continued rapid development will exacerbate this problem. These factors threaten the persistence of the Texas populations and limit their recovery. Translocations are necessary to link Ocelot populations in the US.
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Habitat Partitioning by Sympatric Ocelots and Bobcats: Implications for Recovery of Ocelots in Southern Texas
Southwestern Naturalist, 2009Co-Authors: Jon S. Horne, Aaron M. Haines, Michael E Tewes, Linda L. LaackAbstract:Populations of Ocelots (Leopardus pardalis) have declined during the past century due mainly to loss of habitat resulting in the Ocelot being listed as endangered by the United States Fish and Wildlife Service. In southern Texas, the northern distribution of the Ocelot overlaps the southern distribution of the bobcat (Lynx rufus). Because bobcats could adversely affect populations of Ocelots through interspecific competition, we examined habitat selection of sympatric Ocelots and bobcats to determine if habitat partitioning could be functioning to reduce interspecific interactions. Using radiotelemetry, we analyzed macro-scale (vegetative communities) and micro-scale (structural components) selection of habitats by sympatric Ocelots and bobcats on Laguna Atascosa National Wildlife Refuge, Cameron County, Texas. We looked for differences in placement of home ranges within the general study area, selection of cover within home ranges, and use of structural components of vegetation within types of cover. There was substantial evidence for habitat partitioning with Ocelots selecting 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 ultimo siglo debido principalmente a la perdida de habitat. Como resultado, esta especie ha sido enlistada en peligro de extincion por el United States Fish and Wildlife Service. En el sur de Texas, la distribucion septentrional del Ocelote se sobrepone con la distribucion meridional del lince rojo (Lynx rufus). Debido a que el lince rojo podro ´a afectar negativamente las poblaciones del Ocelote con la competencia interespeco ´fica, examinamos la seleccion de habitat de las dos especies simpatricas para determinar si la particion de ha podo ´a reducir las interacciones interespeco ´ficas. Usando radiotelemetro ´a, analizamos la seleccion de habitat 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 ubicacion de rangos de hogar dentro del area general de estudio, la seleccion del tipo de cobertura dentro del rango de hogar, y el uso de componentes estructurales de vegetacion dentro del tipo de cobertura. Encontramos evidencia substancial de la particion de habitat, con Ocelotes seleccionando a con .75% de cobertura del dosel mientras que el lince rojo seleccionoareas con ,75% de cobertura del dosel. Por lo tanto, la particion de los recursos del habitat podro ´a facilitar la co-existencia entre estas dos especies.
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A habitat-based population viability analysis for Ocelots (Leopardus pardalis) in the United States
Biological Conservation, 2006Co-Authors: Aaron M. Haines, Michael E Tewes, Jon S. Horne, Linda L. Laack, John H YoungAbstract:Abstract Strategies are needed to recover the Ocelot Leopardus pardalis from the endangered species list. Recently, a population viability analysis (PVA) was developed which concluded that combinations of different recovery strategies were needed to effectively reduce Ocelot extinction probability in the United States (US), with habitat protection and restoration identified as the most effective recovery scenario. We expanded this PVA model by incorporating landscape data to develop a more realistic habitat-based PVA for Ocelots in southern Texas. We used RAMAS/ gis software to conduct a habitat-based PVA by linking landscape data with a demographic metapopulation model. The primary goal of this study was to provide a model for evaluating Ocelot recovery strategies in the US. Each model scenario was simulated 1000 times over 50 years and we defined extinction as one individual remaining. Using the RAMAS/ gis program we identified 11 possible Ocelot habitat patches (i.e., subpopulations) occurring in southern Texas. In addition, based on the habitat-based PVA model we found that combinations of different recovery strategies were needed to effectively reduce Ocelot extinction probability in the US, with reducing road mortality the single most effective strategy. Short-term recovery strategies should include reducing Ocelot road mortality, and translocation of Ocelots into the US from northern Mexico. Long-term recovery strategies should include the restoration of habitat between and around existing Ocelot habitat patches and the establishment of a dispersal corridor between Ocelot breeding populations.
Linda L. Laack - One of the best experts on this subject based on the ideXlab platform.
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Food Habits of Ocelots and Potential for Competition With Bobcats In Southern Texas
Southwestern Naturalist, 2013Co-Authors: Susan D. Booth-binczik, Linda L. Laack, Louis C Bender, Robert D. Bradley, Cody W. Thompson, Jerry W. Huntley, Johanna A. Harvey, Jody L. MaysAbstract:Recovery efforts for the endangered Ocelot (Leopardus pardalis) would be aided by knowledge of its feeding ecology in the affected region. We analyzed scat of Ocelots and bobcats (Lynx rufus) from southern Texas. As has been found for most other populations of Ocelots, rodents were the primary prey, but the principal species of rodent, the Mexican spiny pocket mouse (Liomys irroratus), is smaller than the principal prey reported for other populations of Ocelots. Lagomorphs were more common prey than has been reported in other studies of Ocelots, and birds more common prey than in all but one previous study. The diet of bobcats appeared similar overall to the diet of Ocelots, but lagomorphs occurred in a significantly higher proportion of scats from bobcats. The data suggest that bobcats also preyed more heavily on the largest rodents and less on the medium-sized rodents than Ocelots did. There was no clear division by type of habitat; both felids preyed approximately equally on species that are found primarily in grassland and those that are found in thornscrub. Near the United States-Mexico border, where the ranges of these felids overlap, there is the potential for substantial competition for resources between the two species. An important component of efforts to restore the population of Ocelots in this region, therefore, will be a thorough investigation of this possibility. Studies of the dietary differences when both or only one of the felid species is present in an area, use of foraging habitat by both species, and the relationship between densities of prey and felids would allow the likelihood of negative impacts of competition to be fully evaluated.
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SURVIVAL AND SOURCES OF MORTALITY IN OcelotS
Journal of Wildlife Management, 2012Co-Authors: Aaron M. Haines, Michael E Tewes, Linda L. LaackAbstract:Abstract Survival and cause-specific mortality estimates are needed to develop effective conservation strategies for the endangered Ocelot (Leopardus pardalis) in the United States. We radiomonitored 80 Ocelots (36 F, 44 M) from 1983 to 2002 and analyzed survival and cause-specific mortality rates. Pooled estimates of annual survival rates differed between resident (Ŝ = 0.87) and transient (Ŝ = 0.57) Ocelots (P = 0.02); therefore, survival and cause-specific mortality analyses were partitioned for resident and transient Ocelots. Sex-specific annual survival was similar between resident Ocelots (M = 0.92, F = 0.83, P = 0.16) and transient Ocelots (M = 0.53, F = 0.63, P = 0.75). Most mortalities were from human (e.g., Ocelot–vehicle collisions; M = 45%) and natural (e.g., animal attack, disease; M = 35%) sources. Transient Ocelots had higher natural mortality rates (disease, intraspecific mortality; M = 0.26) than resident Ocelots (M = 0.04, P = 0.03). Other sources of mortality did not differ (P ≥ 0.10) be...
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reduced genetic diversity and isolation of remnant Ocelot populations occupying a severely fragmented landscape in southern texas
Animal Conservation, 2011Co-Authors: Aaron M. Haines, Lon I. Grassman, Jan E. Janecka, Michael E Tewes, Linda L. Laack, D B Shindle, Arturo Caso, Brian W DavisAbstract:The Ocelot Leopardus pardalis has become a conservation priority in the US as a result of severe population decline and loss of habitat during the 20th century. Only two small populations remain in this country. Their short-term viability is threatened by the disappearance of dense thornshrub communities, human-caused mortality and demographic stochasticity. The influence these factors have on Ocelot persistence must be considered to develop effective conservation initiatives. We therefore examined neutral genetic diversity and connectivity among Ocelots in the US and northeastern Mexico using 25 autosomal microsatellites and a 395-bp segment of the mitochondrial control region. Genetic variation was lowest in the population occurring on Laguna Atascosa National Wildlife Refuge, Texas (autosomal microsatellite HE = 0.399 and mtDNA-haplotype diversity = 0) and highest in northeastern Mexico (0.637 and 0.73, respectively), while intermediate on private lands in Willacy County, Texas (0.553 and 0.252, respectively). Significant genetic differentiation between the two Texas populations was observed, despite their close proximity (� 30 km). Both populations were also significantly divergent from northeastern Mexico. The absence of any detectable gene flow implies that the human modified landscape of the Lower Rio Grande Valley in southern Texas acts as a strong barrier to Ocelot movement, disrupting metapopulation dynamics and contributing to loss of diversity. As a consequence, continued genetic erosion among the Texas populations is expected. The lack of movement through the fragmented landscape also suggests it is unlikely Ocelots will recolonize unoccupied habitat patches along the Lower Rio Grande and the delta interior where agriculture and urban land uses predominate. The continued rapid development will exacerbate this problem. These factors threaten the persistence of the Texas populations and limit their recovery. Translocations are necessary to link Ocelot populations in the US.
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Habitat Partitioning by Sympatric Ocelots and Bobcats: Implications for Recovery of Ocelots in Southern Texas
Southwestern Naturalist, 2009Co-Authors: Jon S. Horne, Aaron M. Haines, Michael E Tewes, Linda L. LaackAbstract:Populations of Ocelots (Leopardus pardalis) have declined during the past century due mainly to loss of habitat resulting in the Ocelot being listed as endangered by the United States Fish and Wildlife Service. In southern Texas, the northern distribution of the Ocelot overlaps the southern distribution of the bobcat (Lynx rufus). Because bobcats could adversely affect populations of Ocelots through interspecific competition, we examined habitat selection of sympatric Ocelots and bobcats to determine if habitat partitioning could be functioning to reduce interspecific interactions. Using radiotelemetry, we analyzed macro-scale (vegetative communities) and micro-scale (structural components) selection of habitats by sympatric Ocelots and bobcats on Laguna Atascosa National Wildlife Refuge, Cameron County, Texas. We looked for differences in placement of home ranges within the general study area, selection of cover within home ranges, and use of structural components of vegetation within types of cover. There was substantial evidence for habitat partitioning with Ocelots selecting 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 ultimo siglo debido principalmente a la perdida de habitat. Como resultado, esta especie ha sido enlistada en peligro de extincion por el United States Fish and Wildlife Service. En el sur de Texas, la distribucion septentrional del Ocelote se sobrepone con la distribucion meridional del lince rojo (Lynx rufus). Debido a que el lince rojo podro ´a afectar negativamente las poblaciones del Ocelote con la competencia interespeco ´fica, examinamos la seleccion de habitat de las dos especies simpatricas para determinar si la particion de ha podo ´a reducir las interacciones interespeco ´ficas. Usando radiotelemetro ´a, analizamos la seleccion de habitat 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 ubicacion de rangos de hogar dentro del area general de estudio, la seleccion del tipo de cobertura dentro del rango de hogar, y el uso de componentes estructurales de vegetacion dentro del tipo de cobertura. Encontramos evidencia substancial de la particion de habitat, con Ocelotes seleccionando a con .75% de cobertura del dosel mientras que el lince rojo seleccionoareas con ,75% de cobertura del dosel. Por lo tanto, la particion de los recursos del habitat podro ´a facilitar la co-existencia entre estas dos especies.
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A habitat-based population viability analysis for Ocelots (Leopardus pardalis) in the United States
Biological Conservation, 2006Co-Authors: Aaron M. Haines, Michael E Tewes, Jon S. Horne, Linda L. Laack, John H YoungAbstract:Abstract Strategies are needed to recover the Ocelot Leopardus pardalis from the endangered species list. Recently, a population viability analysis (PVA) was developed which concluded that combinations of different recovery strategies were needed to effectively reduce Ocelot extinction probability in the United States (US), with habitat protection and restoration identified as the most effective recovery scenario. We expanded this PVA model by incorporating landscape data to develop a more realistic habitat-based PVA for Ocelots in southern Texas. We used RAMAS/ gis software to conduct a habitat-based PVA by linking landscape data with a demographic metapopulation model. The primary goal of this study was to provide a model for evaluating Ocelot recovery strategies in the US. Each model scenario was simulated 1000 times over 50 years and we defined extinction as one individual remaining. Using the RAMAS/ gis program we identified 11 possible Ocelot habitat patches (i.e., subpopulations) occurring in southern Texas. In addition, based on the habitat-based PVA model we found that combinations of different recovery strategies were needed to effectively reduce Ocelot extinction probability in the US, with reducing road mortality the single most effective strategy. Short-term recovery strategies should include reducing Ocelot road mortality, and translocation of Ocelots into the US from northern Mexico. Long-term recovery strategies should include the restoration of habitat between and around existing Ocelot habitat patches and the establishment of a dispersal corridor between Ocelot breeding populations.
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habitat use of the Ocelot leopardus pardalis in brazilian amazon
Ecology and Evolution, 2019Co-Authors: Andre Luis Sousa Goncalves, Daniel Gomes Da Rocha, Bingxin Wang, Mark I Abrahams, Andre Pinassi Antunes, Hugo C M Costa, Wilson R Spironello, Milton Jose De PaulaAbstract:: Amazonia forest plays a major role in providing ecosystem services for human and sanctuaries for wildlife. However, ongoing deforestation and habitat fragmentation in the Brazilian Amazon has threatened both. The Ocelot is an ecologically important mesopredator and a potential conservation ambassador species, yet there are no previous studies on its habitat preference and spatial patterns in this biome. From 2010 to 2017, twelve sites were surveyed, totaling 899 camera trap stations, the largest known dataset for this species. Using occupancy modeling incorporating spatial autocorrelation, we assessed habitat use for Ocelot populations across the Brazilian Amazon. Our results revealed a positive sigmoidal correlation between remote-sensing derived metrics of forest cover, disjunct core area density, elevation, distance to roads, distance to settlements and habitat use, and that habitat use by Ocelots was negatively associated with slope and distance to river/lake. These findings shed light on the regional scale habitat use of Ocelots and indicate important species-habitat relationships, thus providing valuable information for conservation management and land-use planning.
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Ocelot leopardus pardalis density in central amazonia
PLOS ONE, 2016Co-Authors: Daniel Gomes Da Rocha, Rahel Sollmann, Emiliano Esterci Ramalho, Renata IlhaAbstract:Ocelots (Leopardus pardalis) are presumed to be the most abundant of the wild cats throughout their distribution range and to play an important role in the dynamics of sympatric small-felid populations. However, Ocelot ecological information is limited, particularly for the Amazon. We conducted three camera-trap surveys during three consecutive dry seasons to estimate Ocelot density in Amana Reserve, Central Amazonia, Brazil. We implemented a spatial capture-recapture (SCR) model that shared detection parameters among surveys. A total effort of 7020 camera-trap days resulted in 93 independent Ocelot records. The estimate of Ocelot density in Amana Reserve (24.84 ± SE 6.27 Ocelots per 100 km2) was lower than at other sites in the Amazon and also lower than that expected from a correlation of density with latitude and rainfall. We also discuss the importance of using common parameters for survey scenarios with low recapture rates. This is the first density estimate for Ocelots in the Brazilian Amazon, which is an important stronghold for the species.