Thursday, June 01, 2006
Ocelot Research
POPULATION GENETICS OF OCELOT IN SOUTHERN TEXAS AND NORTHERN MEXICO
Researchers: Jan Janecka, Linda Laack (USFWS), Rodney Honeycutt (TAMU), Michael Tewes
Wildlife genetics is a quickly growing field because it provides new approaches for studying wildlife biology that can supplement more traditional methods such as radio-telemetry. Genetic variation has important impacts in fitness and adaptability of populations. Genetics variation also provides information on population structure, dynamics, history, and distribution of populations. Previous research has documented reduced ocelot genetic variation in southern Texas. This study will further examine population genetics of ocelot in southern Texas and northern Mexico.
We have collected blood samples from radio-collared ocelots for over 20 years and have the largest collection of ocelot samples from southern Texas. We will use microsatellites and mtDNA markers (control region and cytochrome b) to examine population genetics of ocelot. This study has several main objectives: 1) estimate movement between the two remaining ocelot populations in the United States, 2) examine the rate of genetic erosion and the implications it has on conservation decisions, and 3) examine the effects of reduced genetic variation on fitness, and 4) examine the social structure of ocelot. The reduction in genetic variation has important implications on recovery efforts for the ocelot.
HISTORIC PATTERNS IN GENETIC VARIATION OF OCELOT IN THE TAMAULIPAN BIOTIC PROVINCE
Researchers: Jan Janecka, Rodney Honeycutt (TAMU), Michael Tewes
This research project examines the temporal variation of ocelot in southern Texas and northern Mexico. This study will supplement previous work on ocelot genetics that used samples collected in the 1980’s and early 1990’s. In our previous research we found reduced genetic variation in the remaining ocelot populations of southern Texas. There are several theories that may explain this lack of variation, none of which can be rejected or supported because we have no data on historic genetic variation of ocelot in this region.
There is debate as to the implications reductions in genetic variation have on fitness and dynamics of a population. Loss of variation may cause significant reductions in fitness that may lead to extinction of small populations. Also, there is contradictory evidence that any negative effects of genetic depletion are significantly less important than demographic variables. As populations of endangered species become more reduced and isolated, it is important to determine if genetic factors limit the recovery of these species. The ocelot population in southern Texas is among the highest conservation priorities in the United States. Therefore it is important to determine the loss of genetic variation and its effects on the conservation of this species.
We are using microsatellite and mtDNA markers to examine the effects population reductions since turn of the century have had on the genetic variation of ocelot in south Texas. We will compare predicted rates of loss of variation to the genetic depletion observed. Also, we will examine the historic connectivity of ocelot populations in northern Mexico and southern Texas in order to guide any future population supplementation projects.
EVALUATING RECOVERY STRATEGIES FOR AN OCELOT POPULATION IN THE UNITED STATES
Aaron M. Haines, Michael E. Tewes, Linda L. Laack, and William E. Grant
The ocelot (Leopardus pardalis) population in the United States was listed as endangered in 1982, with only two known isolated breeding populations occurring in southern Texas. Conservation concerns for ocelots include loss of dense thornshrub habitat, mortality from ocelot-vehicle collisions, and genetic erosion. In this study, we used a population viability analysis (PVA) to evaluate three recovery strategies (i.e., habitat protection and restoration, road culvert construction, and supplementation of additional ocelots) for ocelot conservation management. We used the VORTEX (Version 9.42) program to conduct our PVA for an ocelot population located in Cameron County, Texas. Each scenario was simulated 500 times over 100 years. We compared the effectiveness of recovery strategies and combinations thereof with estimates of extinction probability. Model scenarios with no recovery strategies predicted an extinction probability of 0.65 to 0.98 for the Cameron population of ocelots over 100 years. The protection and restoration of thornshrub habitat was the most effective recovery strategy, followed by construction of culverts, and supplementation of ocelots being the least effective strategy. Preferred scenarios that reduced ocelot extinction probability to ≤0.01 over 100 years included habitat protection and restoration used simultaneously with construction of culverts, as well as all three recovery strategies used simultaneously. Protection and restoration of ocelot habitat cannot be accomplished without the participation of private landowners. Using an adaptive management approach, future actions need to be taken to monitor ocelot populations and habitats and help reduce the high probability of extinction predicted in our PVA for the ocelot population in Cameron County.
SURVIVAL AND CAUSE-SPECIFIC MORTALITY OF OCELOTS IN SOUTH TEXAS
Researchers: Aaron M. Haines, Michael E. Tewes, and Linda L. Laack
Survival and cause-specific mortality estimates are needed to develop effective conservation strategies for the ocelot in the United States. We analyzed seasonal and annual survival and cause-specific mortality rates of ocelots. We found that survival of resident ocelots was higher than of transient ocelots. Sex-specific annual survival was similar between resident ocelots and transient ocelots. Majority of mortalities observed were human caused, primarily ocelot-vehicle collisions. Transient ocelots suffered from higher natural mortality rates (disease, intraspecific mortality) than resident ocelots. Resident ocelots had higher mortality due to unidentified causes than transient ocelots.
Human population expansion within the Lower Rio Grande Valley of southern Texas will increase transportation related effects and possibly decrease the quantity of ocelot habitat. This expansion could lead to increased ocelot-vehicle collisions and possibly cause more transient behavior within ocelots, thus significantly lowering ocelot survival. Conservation strategies are needed to mitigate these impacts, and the implementation of a population viability analysis will address these concerns.
REPRODUCTIVE ECOLOGY OF OCELOT IN SOUTHERN TEXAS
Researchers: Linda Laack (USFWS), Michael Tewes, Aaron Haines, John Rappole
Data on ocelot reproductive biology is needed to develop models of population viability. The objective of this study was to gather preliminary data on ocelot parturition, fecundity, sex ratios, den characteristics and first year survival for ocelots in south Texas. Adult female resident ocelots were radio-collared and monitored to study their reproductive ecology.
Eight parturition dates ranging from mid-May to late December were observed for 6 female ocelots. Litters consisted of 1-2 kittens with a mean litter size of 1.4. Cumulative sex ratio from this study and historical observations of ocelots in southern Texas was dominated by females 1:2.2 . Six den sites were found in the study. All den sites were in close proximity to (≤ 10 m) to thorn shrub. Adult female ocelots used 2-4 den sites per litter with distance between consecutively occupied den sites ranging from 110-280 m. Ocelots aged ≤ 3 months old had a lower survival than ocelots aged 6-11 months old. Ocelots were shown to have short inter-parturition periods if a litter failed and evidence suggest that ocelots may breed more than once every other year. Results from this study provide preliminary ocelot reproduction estimates to be used in population modeling.
OCELOT SPATIAL PATTERNS RELATIVE TO ROADS IN SOUTHERN TEXAS
Researchers: Jan Janecka, Stephen Webb, Linda Laack (USFWS), Michael Tewes
One of two known ocelot populations occurs in the eastern portion of Cameron County, Texas. The road network in this area is one of the primary mortality threats to ocelots. Road development often leads to increases in human activity, habitat alterations, and road mortality. Consequently, we are exploring the distribution of ocelot home ranges relative to the road density in eastern Cameron County.
We analyzed telemetry locations of 28 ocelots (14 males, 14 females) in southern Texas and classified roads into secondary highway, hard surface, and other roads. We are examining road densities and proximity of telemetry locations to roads. Preliminary analysis suggests that ocelot home ranges have lower secondary highway mean density than the study area and greater hard surface road and other road mean densities. Ocelot locations are at greater distances from secondary roads than from hard surface roads. We are also comparing road ecology patterns in ocelot to bobcat.
Understanding the relationship between road development and ocelot distribution is important in the conservation of ocelot. We will work with U. S. Fish and Wildlife Service, Texas Department of Transportation, and Texas Parks and Wildlife to design management policies that minimize road mortality.
Cooperative funding by the Texas Department of Transportation.
IMPORTANCE OF ROAD ECOLOGY FOR OCELOT
Researchers: Jan Janecka, Michael E. Tewes, Stephen Webb, and Robert Hughes
The reduction of ocelot mortality due to automobile collisions is a priority in management of this endangered species. The primary source of documented mortality for ocelots in Texas is vehicle collisions. A proposed method to minimize the danger of road crossings has been to construct "cat underpasses" in critical areas. The Texas Department of Transportation installed 5 ocelot-crossing structures in Cameron County in an effort to reduce vehicle related deaths of ocelots. Barrier fencing was erected at 4 of the 5 crossing structures in an effort to guide the cats into the structures. The objective of this study was to monitor the use of these structures by mammals with emphasis on possible ocelot usage.
Remote infrared-triggered camera systems were placed at each of these culverts to monitor use by ocelot. Data recorded from the camera systems included date, time and species of animal using the crossing structure. Although no ocelots have been documented in over 700 trap-nights, multiple bobcats and feral house cats have been observed utilizing these structures. Results of this study will be used to plan future crossing structures in sensitive areas, as well as to develop alternatives to reduce road impacts on ocelots.
Cooperative funding by Texas Department of Transportation.
HELMINTH PARASITES OF OCELOTS FROM SOUTHERN TEXAS
Michael Tewes (professor) handling a sedated ocelot.
Researchers: Danny Pence (Texas Tech), Michael Tewes, and Linda Laack (USFW)
In order to recover ocelots, it is imperative we identify potential limiting factors that may negatively affect the population. Large populations of helminth parasites, such as hookworms and ascarid nematodes, could be pathogenic to wild ocelots. Our objective is to identify parasitism occurring in ocelots from southern Texas.
Helminth parasites collected from live-trapped ocelots will be examined for species identification. We have also examined 14 adult ocelots that died from various causes. These parasites are common species found in other wild and domestic felids in southern Texas and could be pathogenic if present in large numbers. To date, none of the adult ocelots examined have been heavily infected with helminth parasites. In fact, all of the ocelots had extremely low numbers of helminth species and individuals. Preliminary results suggest that the adult ocelot population is at little pathogenic risk by helminth parasites. However, since young animals are at higher risk for heavy ascarid infections and other potentially pathogenic helminth species, ocelot kittens and juveniles must be examined to assess the effects of helminth infections and their potential negative effects.
Researchers: Jan Janecka, Linda Laack (USFWS), Rodney Honeycutt (TAMU), Michael Tewes
Wildlife genetics is a quickly growing field because it provides new approaches for studying wildlife biology that can supplement more traditional methods such as radio-telemetry. Genetic variation has important impacts in fitness and adaptability of populations. Genetics variation also provides information on population structure, dynamics, history, and distribution of populations. Previous research has documented reduced ocelot genetic variation in southern Texas. This study will further examine population genetics of ocelot in southern Texas and northern Mexico.
We have collected blood samples from radio-collared ocelots for over 20 years and have the largest collection of ocelot samples from southern Texas. We will use microsatellites and mtDNA markers (control region and cytochrome b) to examine population genetics of ocelot. This study has several main objectives: 1) estimate movement between the two remaining ocelot populations in the United States, 2) examine the rate of genetic erosion and the implications it has on conservation decisions, and 3) examine the effects of reduced genetic variation on fitness, and 4) examine the social structure of ocelot. The reduction in genetic variation has important implications on recovery efforts for the ocelot.
HISTORIC PATTERNS IN GENETIC VARIATION OF OCELOT IN THE TAMAULIPAN BIOTIC PROVINCE
Researchers: Jan Janecka, Rodney Honeycutt (TAMU), Michael Tewes
This research project examines the temporal variation of ocelot in southern Texas and northern Mexico. This study will supplement previous work on ocelot genetics that used samples collected in the 1980’s and early 1990’s. In our previous research we found reduced genetic variation in the remaining ocelot populations of southern Texas. There are several theories that may explain this lack of variation, none of which can be rejected or supported because we have no data on historic genetic variation of ocelot in this region.
There is debate as to the implications reductions in genetic variation have on fitness and dynamics of a population. Loss of variation may cause significant reductions in fitness that may lead to extinction of small populations. Also, there is contradictory evidence that any negative effects of genetic depletion are significantly less important than demographic variables. As populations of endangered species become more reduced and isolated, it is important to determine if genetic factors limit the recovery of these species. The ocelot population in southern Texas is among the highest conservation priorities in the United States. Therefore it is important to determine the loss of genetic variation and its effects on the conservation of this species.
We are using microsatellite and mtDNA markers to examine the effects population reductions since turn of the century have had on the genetic variation of ocelot in south Texas. We will compare predicted rates of loss of variation to the genetic depletion observed. Also, we will examine the historic connectivity of ocelot populations in northern Mexico and southern Texas in order to guide any future population supplementation projects.
EVALUATING RECOVERY STRATEGIES FOR AN OCELOT POPULATION IN THE UNITED STATES
Aaron M. Haines, Michael E. Tewes, Linda L. Laack, and William E. Grant
The ocelot (Leopardus pardalis) population in the United States was listed as endangered in 1982, with only two known isolated breeding populations occurring in southern Texas. Conservation concerns for ocelots include loss of dense thornshrub habitat, mortality from ocelot-vehicle collisions, and genetic erosion. In this study, we used a population viability analysis (PVA) to evaluate three recovery strategies (i.e., habitat protection and restoration, road culvert construction, and supplementation of additional ocelots) for ocelot conservation management. We used the VORTEX (Version 9.42) program to conduct our PVA for an ocelot population located in Cameron County, Texas. Each scenario was simulated 500 times over 100 years. We compared the effectiveness of recovery strategies and combinations thereof with estimates of extinction probability. Model scenarios with no recovery strategies predicted an extinction probability of 0.65 to 0.98 for the Cameron population of ocelots over 100 years. The protection and restoration of thornshrub habitat was the most effective recovery strategy, followed by construction of culverts, and supplementation of ocelots being the least effective strategy. Preferred scenarios that reduced ocelot extinction probability to ≤0.01 over 100 years included habitat protection and restoration used simultaneously with construction of culverts, as well as all three recovery strategies used simultaneously. Protection and restoration of ocelot habitat cannot be accomplished without the participation of private landowners. Using an adaptive management approach, future actions need to be taken to monitor ocelot populations and habitats and help reduce the high probability of extinction predicted in our PVA for the ocelot population in Cameron County.
SURVIVAL AND CAUSE-SPECIFIC MORTALITY OF OCELOTS IN SOUTH TEXAS
Researchers: Aaron M. Haines, Michael E. Tewes, and Linda L. Laack
Survival and cause-specific mortality estimates are needed to develop effective conservation strategies for the ocelot in the United States. We analyzed seasonal and annual survival and cause-specific mortality rates of ocelots. We found that survival of resident ocelots was higher than of transient ocelots. Sex-specific annual survival was similar between resident ocelots and transient ocelots. Majority of mortalities observed were human caused, primarily ocelot-vehicle collisions. Transient ocelots suffered from higher natural mortality rates (disease, intraspecific mortality) than resident ocelots. Resident ocelots had higher mortality due to unidentified causes than transient ocelots.
Human population expansion within the Lower Rio Grande Valley of southern Texas will increase transportation related effects and possibly decrease the quantity of ocelot habitat. This expansion could lead to increased ocelot-vehicle collisions and possibly cause more transient behavior within ocelots, thus significantly lowering ocelot survival. Conservation strategies are needed to mitigate these impacts, and the implementation of a population viability analysis will address these concerns.
REPRODUCTIVE ECOLOGY OF OCELOT IN SOUTHERN TEXAS
Researchers: Linda Laack (USFWS), Michael Tewes, Aaron Haines, John Rappole
Data on ocelot reproductive biology is needed to develop models of population viability. The objective of this study was to gather preliminary data on ocelot parturition, fecundity, sex ratios, den characteristics and first year survival for ocelots in south Texas. Adult female resident ocelots were radio-collared and monitored to study their reproductive ecology.
Eight parturition dates ranging from mid-May to late December were observed for 6 female ocelots. Litters consisted of 1-2 kittens with a mean litter size of 1.4. Cumulative sex ratio from this study and historical observations of ocelots in southern Texas was dominated by females 1:2.2 . Six den sites were found in the study. All den sites were in close proximity to (≤ 10 m) to thorn shrub. Adult female ocelots used 2-4 den sites per litter with distance between consecutively occupied den sites ranging from 110-280 m. Ocelots aged ≤ 3 months old had a lower survival than ocelots aged 6-11 months old. Ocelots were shown to have short inter-parturition periods if a litter failed and evidence suggest that ocelots may breed more than once every other year. Results from this study provide preliminary ocelot reproduction estimates to be used in population modeling.
OCELOT SPATIAL PATTERNS RELATIVE TO ROADS IN SOUTHERN TEXAS
Researchers: Jan Janecka, Stephen Webb, Linda Laack (USFWS), Michael Tewes
One of two known ocelot populations occurs in the eastern portion of Cameron County, Texas. The road network in this area is one of the primary mortality threats to ocelots. Road development often leads to increases in human activity, habitat alterations, and road mortality. Consequently, we are exploring the distribution of ocelot home ranges relative to the road density in eastern Cameron County.
We analyzed telemetry locations of 28 ocelots (14 males, 14 females) in southern Texas and classified roads into secondary highway, hard surface, and other roads. We are examining road densities and proximity of telemetry locations to roads. Preliminary analysis suggests that ocelot home ranges have lower secondary highway mean density than the study area and greater hard surface road and other road mean densities. Ocelot locations are at greater distances from secondary roads than from hard surface roads. We are also comparing road ecology patterns in ocelot to bobcat.
Understanding the relationship between road development and ocelot distribution is important in the conservation of ocelot. We will work with U. S. Fish and Wildlife Service, Texas Department of Transportation, and Texas Parks and Wildlife to design management policies that minimize road mortality.
Cooperative funding by the Texas Department of Transportation.
IMPORTANCE OF ROAD ECOLOGY FOR OCELOT
Researchers: Jan Janecka, Michael E. Tewes, Stephen Webb, and Robert Hughes
The reduction of ocelot mortality due to automobile collisions is a priority in management of this endangered species. The primary source of documented mortality for ocelots in Texas is vehicle collisions. A proposed method to minimize the danger of road crossings has been to construct "cat underpasses" in critical areas. The Texas Department of Transportation installed 5 ocelot-crossing structures in Cameron County in an effort to reduce vehicle related deaths of ocelots. Barrier fencing was erected at 4 of the 5 crossing structures in an effort to guide the cats into the structures. The objective of this study was to monitor the use of these structures by mammals with emphasis on possible ocelot usage.
Remote infrared-triggered camera systems were placed at each of these culverts to monitor use by ocelot. Data recorded from the camera systems included date, time and species of animal using the crossing structure. Although no ocelots have been documented in over 700 trap-nights, multiple bobcats and feral house cats have been observed utilizing these structures. Results of this study will be used to plan future crossing structures in sensitive areas, as well as to develop alternatives to reduce road impacts on ocelots.
Cooperative funding by Texas Department of Transportation.
HELMINTH PARASITES OF OCELOTS FROM SOUTHERN TEXAS
Michael Tewes (professor) handling a sedated ocelot.
Researchers: Danny Pence (Texas Tech), Michael Tewes, and Linda Laack (USFW)
In order to recover ocelots, it is imperative we identify potential limiting factors that may negatively affect the population. Large populations of helminth parasites, such as hookworms and ascarid nematodes, could be pathogenic to wild ocelots. Our objective is to identify parasitism occurring in ocelots from southern Texas.
Helminth parasites collected from live-trapped ocelots will be examined for species identification. We have also examined 14 adult ocelots that died from various causes. These parasites are common species found in other wild and domestic felids in southern Texas and could be pathogenic if present in large numbers. To date, none of the adult ocelots examined have been heavily infected with helminth parasites. In fact, all of the ocelots had extremely low numbers of helminth species and individuals. Preliminary results suggest that the adult ocelot population is at little pathogenic risk by helminth parasites. However, since young animals are at higher risk for heavy ascarid infections and other potentially pathogenic helminth species, ocelot kittens and juveniles must be examined to assess the effects of helminth infections and their potential negative effects.
