Texas Desert Bighorn Numbers Increase

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The desert bighorn sheep is a native of Texas and it has a history that most outdoors lovers have not heard.

On this podcast Chester Moore interviews Froylan Hernandez, desert bighorn sheep program leader for the Texas Parks & Wildlife Department and uncovers some fascinating information about this regal species.

According to Herandez the current population sits at around 1,500 which is remarkable when comparing to the 1970s.

The Sierra Diablo Mountains population, in Culberson and Hudspeth counties, is a result of two successful releases of pen-raised sheep, consisting of 4 rams and 3 ewes in June 1973, and 3 rams and 4 ewes in January 1979. This herd grew to an estimated 100 head in early 1989. It was supplemented with 3 rams from the Sierra Diablo Wildlife Management Area (SDWMA) pens in April 1988, and 28 rams and 8 ewes from the Area pens in October 1989. An additional 10 yearling rams and 1 ewe were released from the brood pen facility in April, 1992 and 25 rams were released in December, 1993. In May 1997, because of ongoing disease problems, the Sierra Diablo Wildlife Management Area brood pen facility was vacated. Forty-five sheep were released into the north end of the Sierra Diablo Mountains. This release consisted of 12 rams, 21 ewes, and 12 lambs.

The Elephant Mountain Wildlife Management Area (EMWMA) herd, in Brewster County, resulted from a release of 10 rams and 10 ewes on February 4, 1987. A supplemental release of 3 rams occurred in April 1988. All of these were pen-raised bighorns from the SDWMA brood facility. These sheep have since increased in number substantially.

The bighorns in the Sierra Vieja Mountains of Presidio County are the result of a release of 4 rams and 1 ewe from the 600-acre Chilicote Ranch brood pasture on March 16, 1987. More sheep were scheduled for release, but the attempt was aborted when the animals could not be trapped.

The Van Horn Mountains herd, in Culberson County, resulted from a release of wild-trapped bighorns from Nevada. In October 1987, 25 sheep, consisting of 5 rams and 20 ewes, were released. An additional 4 rams and 11 ewes were wild-trapped in Nevada and released in October 1988. A total of 22 of these sheep were fitted with telemetry collars to assist in evaluating the restocking effort. High predation losses to mountain lions and drought conditions initially resulted in a decline of the released broodstock.

The Baylor Mountains herd, in Culberson County, resulted from a release of 2 rams and 8 ewes, which were wild-trapped in Nevada in October 1988. This release was supplemented with 4 rams and 7 ewes, in December 1988 from the Chilicote Ranch brood pasture. A total of 15 sheep released in the Baylor Mountains were radio collared to facilitate evaluation of the restocking effort.

The Beach Mountains, in Culberson County, were restocked in May 1991 with 26 bighorns, which were in a temporary holding pen on the Beach Mountain Ranch. These sheep consisted of 1 mature ram, 5 mature ewes, 13 yearling rams, and 4 yearling ewes relocated from the Sierra Diablo brood facility in December 1990, plus 3 lambs born in the holding pen. The Beach Mountains received an additional 12 bighorns from the brood facility in November 1992 consisting of 2 rams and 10 ewes. The sheep were placed in a soft release holding pen awaiting release. These sheep, plus 9 lambs born in the holding pen, were released in June 1993.

In October 1995, 20 bighorn sheep (16 ewes and 4 rams) were transplanted from Nevada to the Black Gap Wildlife Management Area (BGWMA) in Brewster County. Three rams from the EMWMA were subsequently transplanted to augment the existing population and assure breeding. In December 1996, 5 more rams and 5 ewes were transplanted to BGWMA. An additional release of 15 adult ewes and 5 lambs from Nevada was completed in January 1998. Forty-five desert bighorn sheep (23 ewes and 22 rams) were transplanted from Elephant Mountain Wildlife Management Area to Black Gap Wildlife Management Area in December of 2001. All 23 of the ewes and 19 of the rams were fitted with telemetry collars to assist in evaluating the population augmenting effort.

Wildlife managers have recognized the need for systematic surveys to determine desert sheep numbers and trends for many years. During the 1950s many techniques were introduced to determine bighorn sheep populations but most survey methods and census techniques were found to be inadequate. Desert bighorn sheep surveys improved through time as technology advanced. Fall helicopter surveys consistently produced narrower ram:ewe ratios, better correlation of fall lambs to annual recruitment, consistent sex ratios, reliable sex:age ratios, and increased total observations. Systematic desert bighorn sheep aerial population surveys did not occur in Texas prior to 1990. Annual fall helicopter surveys were initiated in West Texas during the fall of 1990.


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