GUADALUPE MOUNTAINS An Administrative History

CHAPTER IX: NATURAL RESOURCE ISSUES (continued)

Trespass Grazing

Trespass grazing has been a problem in the park because of the impact it has on vegetation and water sources, and because it created unnatural competition for the wildlife in the park. Trespass grazers included domestic livestock such as cattle, horses, and sheep, and exotic animals such as Barbary sheep. They entered the park easily because most of the boundary was unfenced. As discussed in Chapter VIII, portions of the boundary most susceptible to trespass grazing have been fenced in recent years, and in 1987, completion of the boundary fence was the number one priority for natural resource management for the park.

In the interest of maintaining friendly relations with neighboring ranchers, domestic livestock found in the park simply were herded off the parklands. However, Park Service and park policies provided for more stringent measures to be taken with exotics. Until 1987, the only exotic animal species threatening the park was the Barbary sheep, or aoudad. Barbary sheep moved into the vicinity from the north, relatives of escapees from a ranch in the Hondo Valley, some 90 miles away. After the escape, around 1950, the animals slowly dispersed southward, reaching the southern Guadalupe Mountains in the late 1970s. Agency policy provided for control or eradication of exotic species that threaten ecological communities and native species. The diets of Barbary sheep overlap with those of mule deer and also would compete with desert bighorn sheep, if they were reintroduced in the park. At Guadalupe Mountains, a management program for Barbary sheep, adopted in 1979, called for direct reduction of the species, through shooting by qualified park personnel. The New Mexico Department of Game and Fish agreed to cooperate with the plan for direct reduction. [28]

Pesticide Control

At Guadalupe Mountains, pesticide control was an issue of concern to resource managers because of the effect of DDT on the peregrine falcons that nest in the park. Because the American peregrine falcon (Falco peregrinus anatum) was recognized as an endangered species, park managers were not alone in their concern. Scientists attributed the decline of the species since the 1950s to increased use of organochlorine pesticides, especially DDT. The falcons feed on insectivorous birds and bats, which may be contaminated with high levels of pesticides. DDE, the chemical resulting from the digestive breakdown of DDT, affects the reproductive system of the falcon, causing weak eggshells that break during incubation. Although the U.S. banned DDT in 1972, farmers in Central and South America, areas where the falcons winter, continued to use the pesticide. [29]

Between 1975 and 1978, falcons nesting in the Peregrine Palace eyrie, above McKittrick Canyon, produced fourteen young. This was one of the most productive eyries recorded in the United States. However, the pair that returned in 1979 produced no offspring, and in 1980 and 1981 only a lone male was observed in the canyon. A pair returned to the canyon eyrie each year from 1983 to 1986, and in 1986 fledged one young bird. In 1987 the pair fledged four offspring. [30]

In 1977 the park cooperated with the Chihuahuan Desert Research Institute and the Texas Department of Parks and Wildlife in a study of peregrine falcons. Analysis of eggshells collected from falcon nests in the area showed them to be 18 percent thinner than was considered normal prior to 1947. Lipids from the egg showed 1,000 ppm of DDE. Eggshells collected in 1984, however, were not unduly thin. [31]

The Endangered Species Act mandated federal agencies to manage their lands affirmatively to preserve or to allow the recovery of endangered species. In 1987, resource managers of Guadalupe Mountains proposed studies to ascertain levels and sources of DDT contamination in local prey species, asserting that failure to address the problem of pesticide contamination could make attempts to manage the peregrine futile. [32]

Endangered Species

Besides the peregrine falcon, resource managers have identified two other endangered species in the park: Sneed's pincushion cactus (Coryphantha sneedii var. sneedii), which grows on limestone ledges at lower elevations; and Lloyd's hedgehog cactus (Echinocereus lloydii), which grows only at low elevations on the west side of the park. A threatened species, McKittrick penny royal (Hedeoma apiculatum), which grows on limestone ledges at higher elevations, has also been found in the park. Field surveys have been made to identify the distribution of these plants within the park and newly found locations are recorded as they are reported. The Fish and Wildlife Service provided recovery plans for each of these species and park managers have been working to implement the recommendations. Before any construction took place in the park, particularly trail construction, resource managers made certain that these species would not be affected, either directly or indirectly, by human-caused disturbances. A monitoring program for known populations also has been established. [33]

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