Santa Cruz Island Reserve

12 Aug, 03 AM - 16 Aug, 03 AM

Our overall objective in this study is to produce a more complete inventory of amphibians, reptiles, and bats of the northern Channel Islands (Anacapa, Santa Cruz, Santa Rosa, and San Miguel). This will include more extensive data on population parameters. Specific goals are to provide detailed, systematic data on: 1) species occurrence ? conduct systematic inventories of the northern Channel Islands, using effective and well-quantified survey techniques; 2) population data ? collect and analyze information on distribution, relative abundance, and habitat occurrence of amphibians, reptiles, and bats on the northern Channel Islands; 3) population genetics and relationships ? collect tissue samples from selected species to allow for comparisons among the islands, and between the islands and the mainland (NOT IMPLEMENTED THIS YEAR). METHODS -- Amphibians and Reptiles We will use a variety of targeted survey methods for this study, including: 1) artificial cover boards 2) drift fence / funnel trap arrays 3) road surveys 4) general surveys of selected sites and habitats The survey will be extensive, covering the entire island. Specific sites for trapping methods (cover boards and funnel traps) will be selected based on preliminary field surveys, and pending any necessary approvals. The trapping methods will not involve digging or significant ground disturbance. We will trap amphibians and reptiles using funnel trap arrays with drift fences (Campbell and Christman 1982, Jones 1986, Corn 1994), and artificial cover boards (Fellers and Drost 1994). We will place traps and / or cover boards at sites in all of the major habitats on the Park islands. For cover boards, we will make use of boards that were previously set out in earlier work on the islands, as well as ?naturally?-occurring human debris, where appropriate. New cover boards will be set out where needed. These boards will consist of 2 cm (3/4 inch) plywood, measuring 60 cm x 120 cm. A typical array installation consists of drift fence (upright metal flashing, plastic, or other material that intercepts the movement of small animals, and turns them in the direction of the fence) arranged in a ?Y?-shape, with pitfall traps and / or funnel traps arranged along the drift fence (Jones 1986). We will experiment with a variety of drift fence installations (including long straight-line fences) to see what arrangement is most effective. Spacing between traps in the array will be 7 m. We will sample trap sites twice a month during the spring and summer. During each session, funnel traps will be placed out and checked every day. Cover boards will be checked once per sampling session. Drift fence arrays will primarily be placed in stream valleys, near cliffs, and other areas where small animal movement tends to be funneled. We anticipate having approximately 15 arrays operating on any one island at a time. These arrays will be moved periodically, to provide thorough coverage of each island. We will conduct night driving surveys (Shaffer and Juterbock 1994) on the main roads on Santa Cruz and Santa Rosa Island, between dusk and 10 ? 11 pm. These surveys are primarily directed toward snakes. We will drive the roads at speeds of 15 ? 20 km/hr, stopping whenever an animal is seen. In addition to the vehicle headlights, we will also have hand-held spotlights for scanning areas alongside the road. All locations will be noted both on hard copy maps and by GPS coordinates. We will generally capture, briefly examine, then release amphibians and reptiles seen along the road. During the examination we will record standard measurements, examine females for reproductive activity, and photograph individuals, as appropriate. Visual encounter surveys (Crump and Scott 1994) will primarily be used to survey for diurnal lizard species, although we also expect to encounter some snakes during these searches. Areas for these surveys will be selected using a stratified random approach to sample the range of habitats and geographic extent of the islands. Particular attention will be given to searching areas not sampled by other methods. As with other methods, animals of particular interest will be captured, their location recorded, and standard measurements recorded. METHODS -- Bats We will use a variety of methods for this study, including: 1) ultrasonic surveys of foraging bats 2) mist-netting at potential feeding and drinking sites 3) counts at known roosts 4) surveys of potential natural and man-made roosts For ultrasonic surveys we will use the Anabat system, which converts ultrasonic vocalizations of bats to time / frequency signals, which are then displayed and stored on a laptop computer. Most of the bats that are known or are likely to occur on the islands (with the exception of some of the Myotis species) produce readily-identifiable feeding calls with the Anabat system. Anabat surveys will be conducted at stationary locations, near likely feeding or drinking sites, or from a vehicle along the roads on the larger islands. For the vehicle surveys, we will drive at speeds of 10-15 km/hr, while scanning with the Anabat recorder. When one or more bats is located, the vehicle will be stopped, a GPS location recorded, and we will track the bat(s) long enough to record a good, identifiable call sequence. Time and other notes will be recorded onto a microcassette recorder. Up to five mist nets will be set up just before dusk in areas where bats are likely to occur ? particularly streams, small ponds and other water sources. At least one person will remain in the vicinity of the nets while they are open, so that bats do not remain in the nets for long. For all bats that are captured, we will record species, sex, reproductive status, and standard measurements. We will also photograph species of particular interest (e.g. new island records). Typically, we will have an Anabat recorder operating while we are mist-netting, and we may record calls of some net-captured individuals after they are identified and released. This will serve as a check on ultrasonic call identifications, particularly for any problematic species (such as Myotis spp). At known roost sites, such as the Pallid Bat and Big-eared Bat roosts at the ranch on Santa Cruz Island, we will set up an automated Anabat / laptop system to record activity and numbers at the roosts at different times of the year. At present, we only know of the two main roost sites on Santa Cruz. If more roosts are found, the systems will be moved from site to site to record at least one month of data per site during the spring, summer, and fall. To locate additional roosts, we will carefully search caves, crevices in cliffs, buildings, cisterns, and other potential roost sites. During these searches, we will look both for roosting bats and for other evidence of bat use, such as guano or prey remains. If we locate sites used by bats, but cannot identify the species present, we may return later with an Anabat recorder or mist nets to obtain a positive identification.

Visit #1795 @Santa Cruz Island Reserve

Approved

Under Project # 1450 | Research

USGS Colorado Plateau Field Station -

research_scientist - US Geological Survey

Reservation Members(s)

Group of 2 Research Assistant (non-student/faculty/postdoc) Aug 12 - 16, 2003 (5 days)
Charles Drost Aug 12 - 16, 2003 (5 days)

Reserve Resources(s) | Create Invoice

Dorm 3 Aug 12 - 16, 2003
Jeep 3 Aug 12 - 16, 2003