U.S. Army Monitors Intruders' Movements

Date:  May 27, 1997
Editor: D'Lyn Ford  (505) 646-6528, dlford@nmsu.edu

LAS CRUCES -- A western whiptail lizard scurries across the desert floor searching for a meal of insect larvae, beetles and termites. The little, brown, spotted reptile carries on its daily routine, not knowing the U.S. Department of Defense is tracking its moves.

In 1989, the U.S. Army at White Sands Missile Range (WSMR), located east of Las Cruces, N.M., began collecting data on the number and distribution of herpetofauna (lizards, snakes and amphibians) species in the area to determine the effect military land use has on wildlife. One goal was to identify sensitive areas that need protection or rehabilitation, as well as those areas that can withstand military activities.

In 1990, the project was turned over to the Cooperative Fish and Wildlife Research Unit, a joint state and federal effort housed at New Mexico State University's College of Agricultural, Consumer and Environmental Sciences .

"People may not realize it, but often munitions explosions cause small wildfires," said Phil Zwank, director of the co-op research unit. "The Army wanted to know what effect their activities have on the surrounding wildlife and how long it takes for animals to return to disturbed areas."

To detect changes in herp numbers, NMSU researchers must first determine the current population of lizards, snakes and amphibians on WSMR.

"Since 1991, students have been collecting data during the summer months when these animals are most active," Zwank said. "To date, 56 herpetofauna species have been documented on WSMR." Lizards and snakes are most common, while turtles are fairly rare. Only one turtle species, the ornate box turtle, has been accounted for in the study.

So far, the whiptail lizard is the most-collected species, accounting for 51 percent of all animals captured. "This is probably because they are active foragers and are highly mobile," said Sean Austin, a recent graduate student in fishery and wildlife sciences involved in the survey.

All other types of lizards make up the second most commonly collected group, followed by snakes, toads, salamanders and turtles. "However, in 1993 and 1994, more snakes and other lizard types, such as the prairie lizard, were collected than whiptails," Austin said. "It's difficult to determine species' populations on WSMR, because the most active animals are easier to capture."

Austin noted that certain animals are more susceptible to a particular trapping method based on their movement. "Lizards are more active and more likely to be trapped than toads, salamanders and turtles, which don't travel far from their immediate habitat."

Animals' movement depends on a variety of factors including rainfall, temperature fluctuations and behavior patterns. "For example, toads limit their above-ground activities based on the amount of water available for rehydration," Austin said. This makes them difficult to study.

Various live traps are used to get an accurate species count, including five-gallon buckets buried in the ground flush with the soil surface. Aluminum sheets connecting the buckets guide the animals into the traps. The animals are shaded by a cover supported by twigs or rocks over the trap.

Researchers also capture the creatures by hand and use glue board traps. All animals are identified, recorded and released, Zwank said.

"More data needs to be collected to get a better estimate of the herp populations," Austin said. Currently, researchers are testing the effectiveness of various traps on different habitats.

Through this ongoing reconnaissance mission, the Department of Defense can examine how the Army's daily operations affect another army -- an army of whiptails, rattlesnakes and spadefoot toads.