San Jacinto Resurvey
  Overview
  Methods
  Birds
  Herpetofauna
  Mammals
  Specimens
  Schedule
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CONTACT:
Phil Unitt
619.255.0235
fax: 619.232.0248
birds@sdnhm.org

Mammals

Rodents and Insectivores
Rodents will be sampled by live-trapping. At each site, we will set out a line of 40 Sherman and 10 Tomahawk traps as close as possible to Grinnell and Swarth’s trapping sites as can be determined from their field notes and as needed to sample the habitat diversity around each site. The traps will be opened for four consecutive days and nights, baited, and provided with cotton batting for the animals’ insulation. The coordinates of the ends and center of each trap line will be recorded by the GPS.

Shrews (and some rodents resistant to other trapping methods) will be sampled by pitfall trapping (see Herpetofauna). Each animal trapped, by any technique, will be identified, weighed, measured (as needed for identification), photographed (as needed for identification), and marked before being released, unless it is retained as a specimen.

Some species, such as the flying squirrel (Glaucomys sabrinus), may require more custom-tailored techniques for detection.

Carnivores
At each of the 20 camp sites we will set up three stations for detection of carnivores. The stations will be distributed to sample the habitat diversity around the sites, and the coordinates of each will be recorded by the GPS. The focus of each station will be a 12-inch metal stake wrapped around its top with a pipe cleaner and baited with a scent lure (Carman’s Pro-Choice) suitable for multiple species of carnivores. The scent is applied to the pipe cleaner with a toothbrush. Below the pipe cleaner, double-sided tape is wrapped around the stake. Placing the bait on a removable stake allows us to remove the scent after the survey. Using a toothbrush to apply lure to a pipe cleaner leaves a consistent amount of lure at each station. At each station, a Game-Vu digital camera is placed 1 to 2 meters from the stake and 20 cm off the ground. The camera is enclosed in a metal box, protecting it from weather, animals, and people (York et al. 2001). The camera is activated by a motion sensor. Also, animals often rub against the stake, leaving hairs on both the pipe cleaner and the double-sided tape, and these hairs (collected and compared with hairs on museum specimens) identify the animal, providing independent corroboration of identifications from the photographs (Ernest et al. 2002, Taberlet et al. 1999). After an animal has visited the station, the stake is cleaned and the pipe cleaner and tape are replaced.

Coyotes photographed by use of motion-detecting camera.

Bats
Bats will be surveyed by means of electronic and audible detection of their vocalizations and mist-net capture. At each of the 20 camp sites we will set up from one to six Anabat detectors, distributed to sample the habitat diversity around the sites and in places where bats are likely to be active (possible roost sites, sources of drinking water, riparian settings, woodland edges and interiors). The coordinates of each detector will be recorded by the GPS. Each detector is placed in a weatherproof plastic container with an extension cable connecting it to a microphone placed 1 meter above ground. Each detector will be operated from dusk to dawn through our stay at each camp site.

Anabat ultrasonic detector.
Angelo Soto

Housing for microphone detecting bat vocalizations.
Angelo Soto

The detector records the bats’ vocalizations in computer memory, and we use a filtering program to sort the recordings by their time/frequency signature. We use the program Analook W to convert the recordings to sonograms, then compare the sonograms visually with a library of bat calls to identify the species.

Sonogram of call of the western mastiff bat (Eumops perotis) filtered through Analook software.

Mist-netting will be used when appropriate to capture bats for species identification. Suitable mist-netting locations include over drinking water sources, in vegetation flyways, and along forested edges. The nets’ situation and location will be recorded by photography and a hand-held GPS unit. Mist-nets will be erected and opened at approximately sunset and will be monitored continuously for a period of at least 3 hours beyond sunset. They will be closed and taken down after the monitoring period. All captured bats will be identified to the species, weighed and measured, photographed, and then released immediately after processing.

Spot-lighting
Some mammals, especially ungulates and rabbits, are best recorded visually. At each camp, we will establish a spot-lighting survey route. In this technique, a team of two mammalogists, each carrying a spotlight, will walk together along a pre-established route at night. Each shines the light back and forth through 180° on one side of the route, covering the full field of vision. Animals are located by their reflected eyeshine and identified through binoculars or spotting scope. The color of the eyeshine also helps identify the species. The location, distance, and direction of the animal are recorded, as with the variable-distance point counts of birds.

All mammals observed incidental to other activities will be noted.

Specimens

Bighorn (Ovis canadensis) bedding place in Deep Canyon, 1908.
Joseph Grinnell

Animals will be collected under permit from the California Department of Fish and Game and U.S. Fish and Wildlife Service (for birds), with a goal of up to three specimens per species per site. Specimens are needed because of the long time-scale on which this study is based and to uphold the highest standard of scientific documentation. Just as the concepts and definitions of some species have changed from 1908 to the present, these are likely to continue changing. For example, Grinnell and Swarth recognized only two species of chipmunk in the San Jacinto Mountains, yet it is now known there are actually three. Without collected specimens the identification of the chipmunks recorded by Grinnell and Swarth would have been lost. Some species, even some with profound differences in biology, differ only subtly in external appearance, making voucher specimens essential to confirming identifications. For birds, migratory individuals often mix with resident populations, and dissection, assessment of physiological condition, and identification of specimens to subspecies are needed in these cases to evaluate a bird’s status accurately. An accurate understanding of what is going on inside an animal is essential to interpreting changes, which can be represented by changes in seasonal activity, breeding, and migration as well as simple occurrence. Furthermore, analysis of DNA may give perspective on a population’s history of dispersal or isolation, so preserving samples of genetic material, with specimens to attest to the samples’ identity, is also critical. It is our goal that a new expedition also serve as a basis for evaluation of future changes. Just as we judge the value of the 1908 expedition, ultimately, on the specimens and data Grinnell and Swarth left for us to evaluate, future generations will judge our effort on the same basis.

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