CRITTERS GIVE CLUES; TOAD TRACKERS SEEK SOLUTIONS FOR LAND USE.

Byline: Greg Botonis Daily News Staff Writer

After months of debate about the closure of 3,000 acres of the Angeles National Forest because of an endangered toad, U.S. Forest Service biologists have taken a new step to better understand the creature's habits and habitat.

Six southwestern arroyo toads were captured May 14 and fitted with dime-size radio transmitters weighing about two grams each, and 10 more toads will be fitted within the next several days.

``This is the best way we know of to study them,'' said Bill Brown, a U.S. Forest Service biologist. ``The more we know about the critters, the greater opportunity we have to make informed opinions.''

The transmitters will let biologists track the Littlerock Creek Canyon toad population and gather data about the toads' habits, including how far they roam from streams, which are breeding grounds in spring and summer, and what time of the year they move into the adjoining mountain terraces.

Such information will let forest officials decide whether to open parts of the closed area, which runs from Littlerock Reservoir back into the San Gabriel Mountains almost to Angeles Crest Highway. The closure has particularly angered off-road vehicle enthusiasts, because it forced them out of a popular off-roading area near the reservoir and closed two vehicle trails.

``Once we figure out their habits, we can then do seasonal closures in the areas they inhabit,'' Brown said. ``If they move up to the terraces in the winter then we know we can open the rest of the area during that period.''

The transmitter packs, which are strapped onto the two- to three-inch long toads with a tiny belt, cost about $30 each.

Biologists track them using hand-held receivers, hooked to antennas like a rooftop television aerial. The receiver beeps when it detects a transmitter: the closer the transmitter, the quicker the beeps.

The biologists return periodically to check where the toads are living, carrying the receivers along the Littlerock Creek but otherwise leaving the toads alone.

``We have to hike through all the inhabited areas, but just tracking them,'' Brown said. ``The less we handle them the better. Our job is to aid and protect the endangered species but we also want the OHVers (off-highway vehicle users) to be able to use the area.''

The arroyo toad, Bufo microscaphus californicus, was declared endangered in 1994. Experts say the toad is near extinction because Southern California has dammed and paved nearly all the streams where it lived, except for far upstream stretches like Littlerock Creek in the San Gabriel Mountains or Piru Creek in Ventura County.

Before getting the transmitters onto the toads, biologists tried to locate the creatures by going out at night with a flashlight and listening for toad calls.

If a biologist heard a toad, he'd shine a flashlight in the direction of the call. That makes the toad's eyes shine.

Biologists will track the transmitter-wearing toads for at least three years. They have to catch them every six weeks to replace the batteries.

Although the transmitters have been used in field studies before, Brown says it is hard to know how they will affect the toads wearing them. The tiny device was designed to allow the creature as much freedom as possible, he said.

Trailing a thin antenna longer than the toad who wears it, the device itself is covered in a pliable tubing that protects it from water and from the sand into which the toad burrows.

``These things were designed to hold up in the toad's natural environment,'' said district ranger Mike Wickman. ``They're a great help in our studies.''

CAPTION(S):

5 Photos

PHOTO (1--Color) Above, a southwestern arroyo toad sticks its head out of the sand near Littlerock Creek. Barely visible to the left of the toad is a thin black antenna attached to a radio transmitter strapped to the toad's back.

(2--Color in AV Edition only) At left, biologists Bill Brown, left, and Ruben Ramirez track toads using radio receivers and antennas.

(3--Color--Ran in AV Edition only) Below, endangered species habitat signs designate the 3,000-acre closed area originating in the Littlerock Reservoir.

(4--Color in AV Edition only) Six toads, like this one, have been fitted with dime-size radio transmitters, which help biologists to track their movements. Ten more toads will be fitted with the devices.

(5) Ruben Ramirez photographs an endangered toad with a radio transmitter strapped to its back, found near Littlerock Creek.

Jeff Goldwater/Daily News