calamaridog
Expedition Leader
Desert drawn
A hard place
By Scott LaFee
7:23 a.m. November 20, 2008
Scientists are conducting a biological inventory of a desolate area near the Salton Sea to determine if wildlife there should be protected. - JOHN GIBBINS / Union-Tribune -
To the casual eye, the old Freeman property west of the Salton Sea is a corrugated landscape of sandy washes and barren wasteland, a bit of low desert baking in the heat of a late October sun.
But Brad Hollingsworth, curator of herpetology at the San Diego Natural History Museum, knows the emptiness is a mirage. Though hardly fecund with life, this parched patch of land is home – or could be home – to an enormously diverse variety of wildlife, from the hairy scorpions, flat-tailed horned lizards and sidewinders that Hollingsworth studies to prairie falcons, bobcats and the occasional bighorn sheep that come down from the rust-colored Santa Rosa Mountains to forage.
“It's a matter of perception,” Hollingsworth says, squinting in the bright sunlight. “If you don't know what you're looking for, there seems to be nothing here, just a big, empty desert.”
Back in 2006, California State Parks acquired the Freeman property, a 4,000-acre checkerboard of parcels bounded by Highway 86 to the east, the Anza-Borrego Desert State Park to the north and west, and the Ocotillo Wells State Vehicular Recreational Area to the south.
State officials are now trying to figure out exactly what to do with the property. Should it be preserved as parkland, its wildlife protected? Or should the land be officially opened to off-road enthusiasts in their motor homes, dune buggies and motorcycles in tow?
Is there room and reason enough for both?
That's why Hollingsworth is here. He and colleagues from the museum, along with other scientists, have been contracted by the state to survey the Freeman property, to produce a biological inventory others will eventually use to help decide the fate of the land.
“It's not our job to determine what happens here, just to assess it,” Hollingsworth says, shifting his four-wheel-drive Jeep into gear for a bumpy, dusty morning tour of the site. “That's politics. This is science.”
A hard place Taking inventory takes time. The Freeman survey will last at least two years. It began in the spring when Jon Rebman, the museum's curator of botany, arrived with a crew to record the desert in bloom before sun and heat reduced most greenery to withered, unrecognizable twigs and straw.
Now it's time for Hollingsworth, along with Scott Tremor, a mammalogist, and Drew Stokes, a field biologist who specializes in bats. Each has the same general mission, but they will use different techniques to count and record the area's largely invisible wildlife.
Hollingsworth's Jeep bumps and rumbles down a wide wash, its walls pocked with odd spherical concretions created by minerals seeping and accumulating in the exposed clay. The surroundings are far from pristine. Tire treads from off-road vehicles groove across the sand and grit in the wash, sometimes veering up and over eroding hillocks or in and through small, steep ravines cut by past flash floods.
You wonder how any life could possibly thrive here if it means sharing the place with armadas of balloon-tired ATVs. But desert creatures are tough, says Eric Hollenbeck, a senior environmental scientist who oversees biological issues in the adjacent Ocotillo Wells district. Life hangs on.
Hollingsworth pulls his Jeep to a stop near a dense stretch of vegetation, not just the ubiquitous creosote and mesquite, but also smoke trees, brittle brush and Palo Verde, a shrubby tree whose seeds were once pounded into flour by Cahuilla and Kumeyaay Indians for mush and cakes.
Hollingsworth clambers out, records the time and temperature, then climbs up the wash wall to a flat rise, where he is monitoring a pit trap with colleagues Kevin Clark, a private biologist, and Melissa Stepek, a collections technician from the museum.
The setup is simple but effective, consisting of a short fence of green mesh staked to the ground in the shape of a Y. When small animals like lizards or mice confront the fence, they tend to follow its course. At points along the way, holes have been dug and 5-gallon buckets inserted. Sometimes the animals fall into the buckets. At the ends of the Y, there are also boxes with hair-trigger doors.
Hollingsworth, Clark and Stepek quickly but carefully check the traps. Each contains a short piece of plastic pipe to provide shelter for anything trapped. “You don't want to just reach in blindly,” Hollingsworth explains, pulling a large black hairy scorpion out of a box trap. “You never know what might be in there.”
Invertebrates like the scorpion aren't particularly of interest, but Stepek duly notes its capture, tapping details into a hand-held GPS device that will be downloaded later into a central database. The other traps are empty, and the researchers quickly move on to the next site, another Y-shaped pit trap, but one also surrounded by dozens of Sherman traps, small metal boxes with doors that snap closed when anything enters.
Baited with oatmeal, the Sherman traps are designed to capture small mammals like the indigenous Merriam's kangaroo rat, local shrews and grasshopper mice.
At midmorning, the traps are all empty and closed. Tremor, the mammalogist, has already been here, checking the traps before the sun came up, then closing them so that no animals are caught later when the desert heat will turn the Shermans into tiny ovens.
Tremor will return in the evening to reopen the boxes for night visitors.
More pit traps are checked. Nothing. Hollingsworth speculates that it's likely most desert denizens are beginning to settle into winter mode, lessening their activity.
“That's probably a good thing because winter is when human activity out here really gets going,” Hollingsworth says.
Tracking lizards Hollingsworth and the others abandon their cars for fieldwork on foot. Trapping alone is a fairly arbitrary way to account for animal diversity and numbers. It's not uncommon, for example, for some animals to be trapped more than once, though every captured animal is marked so that researchers know which are repeaters. (Snakes and lizards are marked with Sharpie pens, the ink falling away when the animal molts.)
The scientists complement their traps by scrupulously, minutely searching for other signs of animals. In some cases, technology helps. Each day, for example, Tremor sets up camera stations at different sites, baiting the area in front of the lens with a scented stick guaranteed to attract larger mammals like bobcats, coyotes and foxes. When an animal gets close enough, a sensor on the camera is triggered and a picture taken with infrared flash.
Tremor also spreads out patches of gypsum powder near the camera, each patch marked by another scent stick. The flour-like gypsum perfectly captures the footprints of passing animals, allowing researchers to gather more details such as likely age and weight or confirm the identity of an animal caught on film.
(Not all photographed animals are the four-footed variety. Though the cameras are well-hidden and moved regularly, Hollingsworth says non-scientists occasionally discover them. “So far, nobody has tinkered with or stolen them. There's a card on each explaining what they are. We get a lot of pictures of naked humans.”)
With the cameras, the animals come to the researchers. Sometimes it's just the opposite. Hollingsworth calls the process “a death crawl,” a painstakingly slow walk (or crawl) across an area searching for minute evidence of smaller, secretive animals like the fringe horned lizard, which is more commonly but inaccurately called a horned or horny toad.
Hollingsworth, Clark and Stepek are all certified horned lizard trackers. They have been trained to discern the difference between the tracks of a horned lizard and those of a hairy scorpion.
“Both walk with their tail up, so there's no telltale drag like there is with other lizards,” Hollingsworth explained. “And if they're comparable in size, the footprints are going to be roughly the same distance apart. But with scorpions, you can see where the three legs on each side have come down in the same spots, leaving little groups of tiny depressions. You don't see that with horned lizards.”
Eyes glued to the ground, the scientists shuffle across some promising ground. Clark says the trick is to keep the eyes moving and scanning, looking for patterns in observed tracks or places likely to harbor horned lizards, which respond to threats not by scampering away, but by lying very still or scuttling deeper into sand.
Very quickly, Clark finds evidence that horned lizards have passed this way and may still be lurking about. He hands Hollingsworth the fresh bit of horned lizard scat. It's the size of a plump, cooked grain of rice, but black and relatively dry. Hollingsworth crumbles it between his fingers, then sniffs it.
“Horned lizards only eat ants,” Hollingsworth says. “You can smell the formic acid. Ants are full of it, which is what keeps most species from eating them. But what makes this so obviously lizard scat are the ants themselves. The scat is full of undigested ant heads and exoskeletons.”
Indeed, it is. Their crumbly remains are positively iridescent. They sparkle in the sun.
Daily ground surveys like these, says Hollingsworth, help the researchers plot where to set traps or direct more focused efforts. Some of his colleagues are compelled to take a more scattershot approach.
Drew Stokes, for example, studies bats. The region is supposed to be home to several species: the Western pippistrelle or canyon bat, the Mexican free-tailed, the California leaf-nosed and others.
But the Freeman property is far from ideal habitat. There's not a lot of permanent water in the area (the polluted Salton Sea doesn't count) to support expansive vegetation that would, in turn, encourage large populations of insects, the bats' primary food source.
“My guess is, there are bats here but not in any great numbers,” says Stokes.
To find out, Stokes employs high and low technologies. Expensive automated field microphones are tuned to the ultrasonic echolocation of bats seeking flying insects at night. The microphones pick up these sounds, which humans cannot hear, and store them on a flash card. A computer program converts the data to signals that can be linked to individual species. “Each bat species has its own fairly unique sonar,” Stokes says.
Other bat-detecting methods are less elaborate. Stokes and others regularly go out on hikes, both day and night, searching for likely roosts, such as caves or crevices.
In places where there is water, Stokes may erect a near-invisible mist net to capture flying bats looking for a drink or for insects attracted to the moisture. “Mist nets aren't really of much use here, and they're labor-intensive,” says Stokes. “You have to stay there with them to pull out any bats that get caught before they get hurt or something.”
Years to come It's past noon and the temperature, even in fall, is becoming uncomfortably hot. The local inhabitants apparently think so, disappearing into cooler nooks and crannies. The museum scientists follow suit, retreating to a rented house until evening, when they will return to open their traps and continue their work.
They have done this for a month. Soon, they will close down operations until next spring, when they will return for another month to trap, count, identify and record. They will return again in October 2009 and again in spring 2010. After that, they will pull all of their data together and issue a report of their findings.
At this point, says Hollingsworth, it's not possible to know with any certainty what they will discover. But one thing seems certain: They will find more than one would expect.
A hard place
By Scott LaFee
7:23 a.m. November 20, 2008
Scientists are conducting a biological inventory of a desolate area near the Salton Sea to determine if wildlife there should be protected. - JOHN GIBBINS / Union-Tribune -
To the casual eye, the old Freeman property west of the Salton Sea is a corrugated landscape of sandy washes and barren wasteland, a bit of low desert baking in the heat of a late October sun.
But Brad Hollingsworth, curator of herpetology at the San Diego Natural History Museum, knows the emptiness is a mirage. Though hardly fecund with life, this parched patch of land is home – or could be home – to an enormously diverse variety of wildlife, from the hairy scorpions, flat-tailed horned lizards and sidewinders that Hollingsworth studies to prairie falcons, bobcats and the occasional bighorn sheep that come down from the rust-colored Santa Rosa Mountains to forage.
“It's a matter of perception,” Hollingsworth says, squinting in the bright sunlight. “If you don't know what you're looking for, there seems to be nothing here, just a big, empty desert.”
Back in 2006, California State Parks acquired the Freeman property, a 4,000-acre checkerboard of parcels bounded by Highway 86 to the east, the Anza-Borrego Desert State Park to the north and west, and the Ocotillo Wells State Vehicular Recreational Area to the south.
State officials are now trying to figure out exactly what to do with the property. Should it be preserved as parkland, its wildlife protected? Or should the land be officially opened to off-road enthusiasts in their motor homes, dune buggies and motorcycles in tow?
Is there room and reason enough for both?
That's why Hollingsworth is here. He and colleagues from the museum, along with other scientists, have been contracted by the state to survey the Freeman property, to produce a biological inventory others will eventually use to help decide the fate of the land.
“It's not our job to determine what happens here, just to assess it,” Hollingsworth says, shifting his four-wheel-drive Jeep into gear for a bumpy, dusty morning tour of the site. “That's politics. This is science.”
A hard place Taking inventory takes time. The Freeman survey will last at least two years. It began in the spring when Jon Rebman, the museum's curator of botany, arrived with a crew to record the desert in bloom before sun and heat reduced most greenery to withered, unrecognizable twigs and straw.
Now it's time for Hollingsworth, along with Scott Tremor, a mammalogist, and Drew Stokes, a field biologist who specializes in bats. Each has the same general mission, but they will use different techniques to count and record the area's largely invisible wildlife.
Hollingsworth's Jeep bumps and rumbles down a wide wash, its walls pocked with odd spherical concretions created by minerals seeping and accumulating in the exposed clay. The surroundings are far from pristine. Tire treads from off-road vehicles groove across the sand and grit in the wash, sometimes veering up and over eroding hillocks or in and through small, steep ravines cut by past flash floods.
You wonder how any life could possibly thrive here if it means sharing the place with armadas of balloon-tired ATVs. But desert creatures are tough, says Eric Hollenbeck, a senior environmental scientist who oversees biological issues in the adjacent Ocotillo Wells district. Life hangs on.
Hollingsworth pulls his Jeep to a stop near a dense stretch of vegetation, not just the ubiquitous creosote and mesquite, but also smoke trees, brittle brush and Palo Verde, a shrubby tree whose seeds were once pounded into flour by Cahuilla and Kumeyaay Indians for mush and cakes.
Hollingsworth clambers out, records the time and temperature, then climbs up the wash wall to a flat rise, where he is monitoring a pit trap with colleagues Kevin Clark, a private biologist, and Melissa Stepek, a collections technician from the museum.
The setup is simple but effective, consisting of a short fence of green mesh staked to the ground in the shape of a Y. When small animals like lizards or mice confront the fence, they tend to follow its course. At points along the way, holes have been dug and 5-gallon buckets inserted. Sometimes the animals fall into the buckets. At the ends of the Y, there are also boxes with hair-trigger doors.
Hollingsworth, Clark and Stepek quickly but carefully check the traps. Each contains a short piece of plastic pipe to provide shelter for anything trapped. “You don't want to just reach in blindly,” Hollingsworth explains, pulling a large black hairy scorpion out of a box trap. “You never know what might be in there.”
Invertebrates like the scorpion aren't particularly of interest, but Stepek duly notes its capture, tapping details into a hand-held GPS device that will be downloaded later into a central database. The other traps are empty, and the researchers quickly move on to the next site, another Y-shaped pit trap, but one also surrounded by dozens of Sherman traps, small metal boxes with doors that snap closed when anything enters.
Baited with oatmeal, the Sherman traps are designed to capture small mammals like the indigenous Merriam's kangaroo rat, local shrews and grasshopper mice.
At midmorning, the traps are all empty and closed. Tremor, the mammalogist, has already been here, checking the traps before the sun came up, then closing them so that no animals are caught later when the desert heat will turn the Shermans into tiny ovens.
Tremor will return in the evening to reopen the boxes for night visitors.
More pit traps are checked. Nothing. Hollingsworth speculates that it's likely most desert denizens are beginning to settle into winter mode, lessening their activity.
“That's probably a good thing because winter is when human activity out here really gets going,” Hollingsworth says.
Tracking lizards Hollingsworth and the others abandon their cars for fieldwork on foot. Trapping alone is a fairly arbitrary way to account for animal diversity and numbers. It's not uncommon, for example, for some animals to be trapped more than once, though every captured animal is marked so that researchers know which are repeaters. (Snakes and lizards are marked with Sharpie pens, the ink falling away when the animal molts.)
The scientists complement their traps by scrupulously, minutely searching for other signs of animals. In some cases, technology helps. Each day, for example, Tremor sets up camera stations at different sites, baiting the area in front of the lens with a scented stick guaranteed to attract larger mammals like bobcats, coyotes and foxes. When an animal gets close enough, a sensor on the camera is triggered and a picture taken with infrared flash.
Tremor also spreads out patches of gypsum powder near the camera, each patch marked by another scent stick. The flour-like gypsum perfectly captures the footprints of passing animals, allowing researchers to gather more details such as likely age and weight or confirm the identity of an animal caught on film.
(Not all photographed animals are the four-footed variety. Though the cameras are well-hidden and moved regularly, Hollingsworth says non-scientists occasionally discover them. “So far, nobody has tinkered with or stolen them. There's a card on each explaining what they are. We get a lot of pictures of naked humans.”)
With the cameras, the animals come to the researchers. Sometimes it's just the opposite. Hollingsworth calls the process “a death crawl,” a painstakingly slow walk (or crawl) across an area searching for minute evidence of smaller, secretive animals like the fringe horned lizard, which is more commonly but inaccurately called a horned or horny toad.
Hollingsworth, Clark and Stepek are all certified horned lizard trackers. They have been trained to discern the difference between the tracks of a horned lizard and those of a hairy scorpion.
“Both walk with their tail up, so there's no telltale drag like there is with other lizards,” Hollingsworth explained. “And if they're comparable in size, the footprints are going to be roughly the same distance apart. But with scorpions, you can see where the three legs on each side have come down in the same spots, leaving little groups of tiny depressions. You don't see that with horned lizards.”
Eyes glued to the ground, the scientists shuffle across some promising ground. Clark says the trick is to keep the eyes moving and scanning, looking for patterns in observed tracks or places likely to harbor horned lizards, which respond to threats not by scampering away, but by lying very still or scuttling deeper into sand.
Very quickly, Clark finds evidence that horned lizards have passed this way and may still be lurking about. He hands Hollingsworth the fresh bit of horned lizard scat. It's the size of a plump, cooked grain of rice, but black and relatively dry. Hollingsworth crumbles it between his fingers, then sniffs it.
“Horned lizards only eat ants,” Hollingsworth says. “You can smell the formic acid. Ants are full of it, which is what keeps most species from eating them. But what makes this so obviously lizard scat are the ants themselves. The scat is full of undigested ant heads and exoskeletons.”
Indeed, it is. Their crumbly remains are positively iridescent. They sparkle in the sun.
Daily ground surveys like these, says Hollingsworth, help the researchers plot where to set traps or direct more focused efforts. Some of his colleagues are compelled to take a more scattershot approach.
Drew Stokes, for example, studies bats. The region is supposed to be home to several species: the Western pippistrelle or canyon bat, the Mexican free-tailed, the California leaf-nosed and others.
But the Freeman property is far from ideal habitat. There's not a lot of permanent water in the area (the polluted Salton Sea doesn't count) to support expansive vegetation that would, in turn, encourage large populations of insects, the bats' primary food source.
“My guess is, there are bats here but not in any great numbers,” says Stokes.
To find out, Stokes employs high and low technologies. Expensive automated field microphones are tuned to the ultrasonic echolocation of bats seeking flying insects at night. The microphones pick up these sounds, which humans cannot hear, and store them on a flash card. A computer program converts the data to signals that can be linked to individual species. “Each bat species has its own fairly unique sonar,” Stokes says.
Other bat-detecting methods are less elaborate. Stokes and others regularly go out on hikes, both day and night, searching for likely roosts, such as caves or crevices.
In places where there is water, Stokes may erect a near-invisible mist net to capture flying bats looking for a drink or for insects attracted to the moisture. “Mist nets aren't really of much use here, and they're labor-intensive,” says Stokes. “You have to stay there with them to pull out any bats that get caught before they get hurt or something.”
Years to come It's past noon and the temperature, even in fall, is becoming uncomfortably hot. The local inhabitants apparently think so, disappearing into cooler nooks and crannies. The museum scientists follow suit, retreating to a rented house until evening, when they will return to open their traps and continue their work.
They have done this for a month. Soon, they will close down operations until next spring, when they will return for another month to trap, count, identify and record. They will return again in October 2009 and again in spring 2010. After that, they will pull all of their data together and issue a report of their findings.
At this point, says Hollingsworth, it's not possible to know with any certainty what they will discover. But one thing seems certain: They will find more than one would expect.