Boyd Deep Canyon Desert Research Center

17 Apr, 05 PM - 17 Apr, 05 PM

Statement of Issue Bats are increasingly recognized as important components of natural communities, as sensitive indicators of overall environmental conditions, for their control of insects, and for pollinating agave and cactus species,. The Western Yellow bat (L. xanthinus) is one of California?s 23 species of bat present in the state (Bat Conservation International,2012). L. xanthinus is also one of the most poorly understood bat species with very little information known about its specific occurrence patterns, natural history or ecological needs. The species has numerous gaps in knowledge regarding baseline data regarding the species distribution, habitat requirements, migration, activity patterns (both daily and seasonally) and threats including palm frond trimming and pesticide use in orchards. The information gained as a result of my proposed research will create a baseline assessment of the patterns of occurrence of this species throughout much of the Colorado Desert and will provide an analysis of habitat characteristics where the bats occur compared to where they are absent. These data will be an asset to the land managers which have or may have western yellow bats present on their lands, providing insights as to how public use, fire and hydrology affect the bats? occupancy on their lands. As this species is also one of the 27 species protected under the Coachella Valley Multiple Species Habitat Conservation Plan (CVMSHCP), any knowledge and insight gained about the distribution and roost selection preferences of the species will greatly aid land managers in conserving the species. Objectives 1.) Gather baseline data regarding the occupancy of L. xanthinus in areas in which the native Desert Fan Palm (Washingtonia filifera) is distributed. 2.) Acquire statistical data on the habitat characteristics of oases where L. xanthinus are detected and contrast those with conditions where they are not detected. The environmental variables I will collect at each oasis will include: number of palm trees, area of palm oasis, palm density, length of palm skirts, human disturbance, invasion of Tamarix spp., proximity to other palm clusters/oases (i.e. isolation), surface water availability, distance to closest water source, and fire history. My specific objective is to test the hypothesis that western yellow bats are selective in their preference for seeking out a palm oases as roosting habitat, and that the suite of variables I will measure will distinguish occupied versus unoccupied oases. Methods Each of the outlined palm oases will be surveyed acoustically with an Anabat SD2 bat detector. Visual confirmation of the species will be assessed using a spot light, which in conjuncture with the bat detector provides active monitoring. All surveys will begin a half hour before sunset and end an hour after sunset, providing each site with one and a half hours of monitoring for the presence of L. xanthinus. The best time to observe L. xanthinus, is at emergence time of the roost (Western Bat Working Group, 2007). The bats medium size and yellow coat make it fairly easy to identify in the field, compared to other bat species that may also occupy the biotic community in a palm oasis. All data collection involving palm oasis parameters and GPS data collection will be conducted prior to starting acoustic surveys. All outlined palm oases will be surveyed, via active monitoring, at least once. If L. xanthinus cannot be confirmed through acoustic and visual affirmation on the first round of surveys than those oases where the bats are not detected will be resurveyed up to two more times (up to a maximum of three surveys) or until a detection is made. Any necessary secondary surveys will be conducted after all initial surveys are completed and the same follows for any tertiary survey needs. The actual number of surveys conducted will vary anywhere from a minimum of 40 nights of surveys to a maximum of 120 nights of surveys. Collections Of the forty palm oases studied acoustically, eight to ten sites will be selected for capture surveys. Sites used for capture need to have water available at the surface, in or nearby the palm oasis. Tentative sites for mist netting are listed below: Grapevine Canyon (CDFG) Deep Canyon (UCR) Palm Canyon (ACBCI) Mc Callum Oasis (CNLM) Magnesia Canyon (CDFG) Whitewater Canyon (TWC) Murray Canyon (ACBCI) Boo Hoff (BLM) Cottonwood Springs (NPS) The purpose of capturing bats is to confirm the presence of L. xanthinus at the site, as well as to aid in the classification of other bat species present in the palm oasis. None of the bats captured will be collected. All species captured will be individually documented by species and other physical attributes that may offer insight as to the use of the palm oasis as a roosting location for bats present. Only Mr. Stokes posses a valid scientific collecting permit from the California Department of Fish and Game. A copy of the permit is attached at the end of this document. Only Mr. Stokes will be processing bats captured in the mist net. Analysis Surveys will be conducted using an Anabat SD2, bat detector. Active monitoring will be employed, by which a PDA unit attached to the Anabat acoustic device will show real time calls from bats at the site and allow for spot lighting bats, in which L. xanthinus call is displayed on PDA screen attached to the Anabat. Spot lighting and video recording bat during the field survey will be used as a means of confirming the presence of L. xanthinus at the palm oasis site during flight in the palm oasis. Species is fairly easy to identify during emergence from roost and exhibits a distinctive flight pattern, as specified in the Western Bat Working Groups survey recommendations (2007). Flight is slow and steady. All bat call information will also be recorded onto a memory card by which all calls collected will be screened through the ANALOOK program, in which a screening filter will be used to remove excess noise and isolate quality calls within a sequence. Calls and sequences will be compared to call libraries acquired from Chris Corben (Anabat bat detector creator) and Drew Stokes (bat biologist who has done previous studies on western yellow bats in the Indian Canyons Tribal Park). Species is easy to identify acoustically, but there can be some acoustic overlap with Lasiurus borealis and Eptesicus fuscus (Western Bat Working Group, 2007). With the employment of mist-netting at the sites that have surface water available or steep canyon walls, another means of species confirmation will be accessed through capture, as well as other species which may be difficult to access acoustically. This form of capture technique is extremely helpful in providing insight into how bat species use the site. Statistical techniques/mathematical models I expect to compare environmental characteristics of occupied versus unoccupied sites using a Logistic Regression analysis. My dependent variable will be occupancy (1 = detected, 0 = undetected), and my independent variables will be environmental characteristics of the individual palm oases, including: number of palm trees, area of palm oasis, palm density, mean length of palm skirts, human disturbance (categorical variable 0 = rarely visited, 1 = regular daytime but no nighttime human use, 2 = daytime and nighttime use (i.e. campground), invasion of Tamarix spp., distance to other palm clusters/oases (i.e. isolation), surface water availability (categorical variable 0 = no surface water, 1 = surface water present), distance to closest water source, and fire history (categorical variable 0 = no evidence of recent fires, skirts reach to the ground, 1 = fire within the past 10 or more years ? skirts well formed near the top of the palm but not extending below half of the palm height, 3 = recent fire ? charred palm trunks and little or no skirt development. Safety In order to conduct this study, hiking after dark will occur after the acoustic monitoring and mist netting are completed. The initial hike out to the palm oasis to be surveyed will be done during daylight hours, as well as collection of data regarding palm oasis parameters outlined in the procedure section. Each survey will include a schedule with the thesis advisor, landowner agency and friends/parents, with phone confirmation prior to embarking and after returning from each survey. All acoustic surveys will be conducted with two or more surveyors who will be in constant contact throughout the survey period. Each will have a working cell phone/walkie-talkie, water, flashlight with extra batteries, and first aid kit. No one will be working alone at any time. All surveyors will wear long pants and sturdy hiking boots. Each survey will include a safety discussion with all new participants, detailing behaviors to avoid, such as contact with poisonous snakes, spiders, and scorpions (no handling, be able to clearly see the ground before stepping, no reaching into spaces where the ground cannot be clearly seen). A few sites that have surface water will be used to set up mist nets to capture bats. Only Mr. Stokes will be able to handle the bats that are caught in the net. Access to study sites All means of access to the study site, palm oasis, will be done on foot. Any and all field equipment to be used will be carried in by the Lead Investigator, Danielle Ortiz, and 2-3 volunteer assistants that have worked alongside Ms. Ortiz for multiple years on various wildlife monitoring programs for the Santa Rosa and San Jacinto Mountains National Monument. There are some sites outlined in the description of study area section mentioned previously, that will include travel into wilderness areas. All rules and regulations associated with entry into wilderness areas will be executed as specified by the park?s wilderness management plan. Any palm oasis sites that will require camping will only be for the duration of one night and will only be for a group of two to four individuals.

Visit #28403 @Boyd Deep Canyon Desert Research Center

Approved

Under Project # 25186 | Research

Identifying patterns of occuancy by western yellow bats (Lasiurus xanthinus) in palm oases in the lower Colorado Desert: What environmental factors limit or facilitate their occurance?

graduate_student - Green Mountain College

Reservation Members(s)

Danielle Ortiz Apr 17, 2012 (1 days)
Danielle Ortiz Apr 17, 2012 (1 days)
Danielle Ortiz Apr 17, 2012 (1 days)
Group of 5 Volunteer Apr 17, 2012 (1 days)

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