Ecology of the Mountain Lion on Big Bend Ranch State Park in Trans-Pecos Texas August 1, 1999 Ecology of the Mountain Lion on Big Bend Ranch State Park in the Trans-Pecos Region of Texas FINAL REPORT Wildlife Division Research Study Project Number 86 By Michael T. Pittman Gilbert J. Guzman Billy Pat McKinney November 1, 2000 Ecology of the Mountain Lion on Big Bend Ranch State Park in the Trans-Pecos Region of Texas 1 Abstract Twenty-one mountain lions (Puma concolor) were captured on Big Bend Ranch State Park (BBRSP), 18 December 1992 - 31 August 1997, using leghold snares or trained hounds. Captured lions were examined and aged, and morphological measurements were recorded. Sixteen lions were fitted with radio transmitters operating on individual frequencies. Collared lions were monitored from the ground and fixed-wing aircraft. One radio failed to work, but a total of 711 locations was recorded for 10 male and 5 female radio-collared mountain lions. Home ranges were delineated for 6 male and 5 female lions. Average annual ranges (100% minimum convex polygon) for adult male lions (348.6 km2 or 86,140 acres) were 59.1% larger (P<0.05) than for adult female mountain lions (205.9 km2 or 50,878.8 acres). Average percent overlap (100% minimum convex polygon) of annual female-female, male-male, and female-male lion ranges were 26.1, 22.9, and 28.9, respectively. Annual shifts were apparent (P<0.05) for female lions and for the cumulative male mountain lion ranges. Analysis of fecal scats (n=135) indicated collared peccary (Tayassu tajacu) and mule deer (Odocoileus hemionus) were preferred prey and were consumed almost equally. Genetic analysis, comparing lions from this study to individuals from South Texas, defined two distinct groups of mountain lions with evidence of reduced gene flow between the groups and indicated the effective number of breeding individuals in the West Texas population may be greater than for South Texas. Mountain lion density (#/100 km2 or 24,710.4 acres) ranged from 0.26-0.59. Observed and deduced lion litters (n=13) indicated minimum mean litter size was 1.54. A total of 19 mountain lions was killed, 17 during and 2 after the study. Causes of mortalities included predator control practices on private lands near BBRSP (n=15), capture activities (n=3), and shooting by a concerned citizen (n=1). The mountain lion population on BBRSP was limited by high mortality rates of female and male mountain Billy Pat McKinney with large male mountain lion that has been immobilized and radio collared. Photo by Gilbert Guzman. lions. A follow up survey conducted 2 years after completion of this study indicated a moderate replacement of resident lions on BBRSP. I. OBJECTIVES 1. Determine home ranges of male and female collecting blood samples for DNA and adult lions on Big Bend Ranch State Park disease analysis. (BBRSP), and estimate population density. 4. Evaluate diets of mountain lions by analyzing 2. Determine reproductive potential of female fecal samples. lions and monitor mortality rates, survival, and dispersal of young lions after they 5. Improve the department's knowledge of the become independent from their mothers. technical requirements and support needed to conduct mountain lion research. 3. Evaluate the genetics and health of the mountain lion population at BBRSP by Ecology of the Mountain Lion on Big Bend Ranch State Park in the Trans-Pecos Region of Texas 1 Abstract Twenty-one mountain lions (Puma concolor) were captured on Big Bend Ranch State Park (BBRSP), 18 December 1992 - 31 August 1997, using leghold snares or trained hounds. Captured lions were examined and aged, and morphological measurements were recorded. Sixteen lions were fitted with radio transmitters operating on individual frequencies. Collared lions were monitored from the ground and fixed-wing aircraft. One radio failed to work, but a total of 711 locations was recorded for 10 male and 5 female radio-collared mountain lions. Home ranges were delineated for 6 male and 5 female lions. Average annual ranges (100% minimum convex polygon) for adult male lions (348.6 km2 or 86,140 acres) were 59.1% larger (P<0.05) than for adult female mountain lions (205.9 km2 or 50,878.8 acres). Average percent overlap (100% minimum convex polygon) of annual female-female, male-male, and female-male lion ranges were 26.1, 22.9, and 28.9, respectively. Annual shifts were apparent (P<0.05) for female lions and for the cumulative male mountain lion ranges. Analysis of fecal scats (n=135) indicated collared peccary (Tayassu tajacu) and mule deer (Odocoileus hemionus) were preferred prey and were consumed almost equally. Genetic analysis, comparing lions from this study to individuals from South Texas, defined two distinct groups of mountain lions with evidence of reduced gene flow between the groups and indicated the effective number of breeding individuals in the West Texas population may be greater than for South Texas. Mountain lion density (#/100 km2 or 24,710.4 acres) ranged from 0.26-0.59. Observed and deduced lion litters (n=13) indicated minimum mean litter size was 1.54. A total of 19 mountain lions was killed, 17 during and 2 after the study. Causes of mortalities included predator control practices on private lands near BBRSP (n=15), capture activities (n=3), and shooting by a concerned citizen (n=1). The mountain lion population on BBRSP was limited by high mortality rates of female and male mountain Billy Pat McKinney with large male mountain lion that has been immobilized and radio collared. Photo by Gilbert Guzman. lions. A follow up survey conducted 2 years after completion of this study indicated a moderate replacement of resident lions on BBRSP. I. OBJECTIVES 1. Determine home ranges of male and female collecting blood samples for DNA and adult lions on Big Bend Ranch State Park disease analysis. (BBRSP), and estimate population density. 4. Evaluate diets of mountain lions by analyzing 2. Determine reproductive potential of female fecal samples. lions and monitor mortality rates, survival, and dispersal of young lions after they 5. Improve the department's knowledge of the become independent from their mothers. technical requirements and support needed to conduct mountain lion research. 3. Evaluate the genetics and health of the mountain lion population at BBRSP by 2 Ecology of the Mountain Lion on Big Bend Ranch State Park in the Trans-Pecos Region of Texas Ecology of the Mountain Lion on Big Bend Ranch State Park in the Trans-Pecos Region of Texas 3 II. BACKGROUND III. STUDY AREA Since 1983, Texas Parks and Wildlife (TPW) has This study was conducted in mid-elevation desert Big Bend Ranch State Park, which is owned by Figure 1. collected mountain lion sightings and mortality scrub and desert grassland habitats in a locale Texas Parks and Wildlife, contains approximately data statewide (Job No. 69, Federal Aid Project with an unusually large number of perennial 1,100 km2 (271,814.8 acres) located within the W-125-R). These data seem to indicate increas- water sources for the region. The widely distrib- Chihuahuan Desert in southwestern Brewster ing populations in the west, central, and southern uted and abundant perennial water of the study and southeastern Presidio Counties (Fig. 1). portions of Texas with isolated occurrences in area made the site unique within the Trans-Pecos BBRSP is situated north of the Mexican State Trans-Pecos North and East Texas (Russ 1992). However, Region. Despite their geographic proximity, the of Chihuahua and is separated from it by the this information alone does not produce accurate BBRSP habitats stand in sharp contrast to the Rio Grande. Big Bend National Park and the estimates of lion population densities for the state low desert scrub and isolated montane habitats of town of Lajitas, Texas are located to the east and must be supported by research on lion Big Bend National Park. BBRSP was considered and the city of Presidio to the west. ecology in the respective regions. This study is an ideal site for obtaining data comparative to the first attempt by TPW to supplement mountain most of the other Texas studies because BBRSP The most distinctive feature of BBRSP is its lion status information with field research. and Big Bend National Park were of similar size. topography. The terrain is rugged, ranging from Study Area broad mesa tops to steep canyons draining into Research on mountain lions in Texas has been In this study, research emphasis was placed on the Rio Grande. Elevations range from 700 m limited primarily to the Chihuahuan Desert the basic factors affecting mountain lion popula- (2,296 ft.) at Lajitas, Texas along the Rio Grande 28 cm (11.0 inches) per year with most falling Region and includes studies by McBride (1976), tions: reproductive rate, mortality rates of different to 1,565 m (5,135 ft.) at the peak of Oso from July through October in the form of torrential Smith et al. (1986), Pence et al. (1986), Leopold age groups, and juvenile dispersal rate. Juvenile Mountain (Deal 1976a,b). Approximately 100 thunderstorms. Occasional winter snowfalls and Krausman (1986), Waid (1990), Packard dispersal rate is an important factor because it perennial springs and associated riparian areas contribute to the annual precipitation. (1991), and Ruth (1991). The only studies may act as a population regulating mechanism are scattered throughout the park. conducted outside Big Bend National Park were that results in the colonization of previously Average annual temperature is 19oo C (66 F) and Smith et al. (1986) in the Guadalupe Mountains, unoccupied habitat and also contributes to gene The climate of BBRSP is characterized as the frost-free season is 230-245 days long and McBride (1976) who did some of his work in flow (Greenwood 1980).