A Survey of Flora and Fauna on Bracken Cave Property Techniques in Wildlife Management Project Spring 2013

1 A Survey of Flora and Fauna on Bracken Cave Property Techniques in Wildlife Management Project Spring 2013 Texas State University, San Marcos‐ Department of Biology Ring‐tailed cat photo by Kendall AuBuchon Edited by Thomas R. Simpson Jacqueline Ferrato 2 INTRODUCTION Bat Conservation International (BCI) was founded in 1982 with a mission to conserve the world’s bats and their ecosystems in order to ensure a healthy planet. In 1991 BCI pursued that commitment by purchasing five acres surrounding the world’s largest bat colony, Bracken Bat Cave (BCI 1999). Bat Conservation International stewards the entire property by protecting endangered birds and providing efforts to restore the land by removing invasive species and revitalizing the native plants and animals on the property (Moore 2005). The Bracken Cave property is noted to be an area with a high concentration of invertebrates and vertebrates. In order to accomplish the desired restoration efforts a baseline inventory must be conducted to acquire a basal knowledge of the plants and animals residing in the area. The Bracken Cave property is primarily composed of oak‐juniper and mixed brush woodland with juniper encroachment. The comfort‐rock outcrop complex and rumple‐comfort association characterizes the land (Moore 2005). The parent material is residuum weathered from limestone. The landform is comprised of plains with mixed grassland and midgrass oak savannah including a landscape of plateaus (USDA 2012). The hydrologic soil group consist of gravelly clay loam 0‐10 inches, very gravelly clay 10‐28 inches and bedrock from 28‐36 inches (More 2005). Historically the property is believed to be an area that was once predominantly grassland studded with occasional oak trees (Moore 2005). Our objectives involved determining the species richness and diversity of avifauna, herpetofauna, mammals, and vegetation on the Bracken Bat Cave and Natural Reserve area through a baseline inventory of various survey techniques. The purpose of conducting a baseline inventory involves recording the important community conservation values such as the species composition and richness of a variety of different biota and the current conditions of the property. Baseline information establishes the foundation from which future management plans will be generated. By documenting 3 current conditions a foundation is established to provide future stewardship guidelines and management activities (Land Trust Alliance 2011). STUDY SITE The Bracken Bat Cave property consists of 282 ha (697 ac) of grassland and woodland habitat located northeast of San Antonio in Comal County. This area can potentially support unique flora and fauna as it lies at the juncture between two eco‐regions, the Edwards Plateau and the Blackland Prairie. This property is of ecological importance because it is home to the largest bat colony in the world and provides habitat for endangered birds; however, it is surrounded by housing development, and urban expansion has increased over the past 20 years since BCI acquired ownership of the cave. The survey was conducted on three separate weekends with the first being Feb. 15‐17, second March 8‐10, and the final trip March 28‐30. Ten survey points were selected with a minimum distance between each point of 250 m to prevent sample overlap. Ten points were selected based on habitat type, either forested or open grassland, and used as sampling sites. The sites were selected to provide an equal mixture of grass prairie and dominate tree cover (Figure 1). 4 Figure 1. Bracken Bat Cave property boundary with ten sampling sites, including the bat cave located at point 8 (29.687057°N 98.352532°W). Coordinates for all points found in Appendix B. 5 AVIFAUNA Sara Miller, Mindy Murray, Michelle Rivera, Katelyn Turner METHODS Point counts were chosen for sampling the bird community because this technique is widely used and requires less time and effort than other survey methods (Forcey et al. 2006). Points were located in two habitat types, grassland and woodlands, to adequately represent the habitat found on the BCI property. A group of 4 researchers undertook this study, two as scribes and two as observers, working in pairs. Periodically other researchers had to stand in for individual surveyors due to schedule conflicts; however, efforts were made to curtail personnel substitutions to maximize consistency. Morning observations began at first light, or as soon as possible thereafter, in order to survey during the “dawn chorus” when birds are more active; and, on average, evening observations began 3‐4 hours before dusk and ended no later than sundown (Carlton and Mooy 2005). Each team of researchers 6 surveyed the same 5 points each iteration (points 1‐5 or 6‐10), and the order of site visits was reversed on alternating days to reduce the possibility of skewed data among sites due to time of day. After arriving at each point, surveyors observed a 1‐min rest period followed by a 5‐min observation period (Hipperson 2010). During the observation period, all birds seen or heard within a 50‐m radius were recorded (Dettmers 1999). Aside from birds of prey, flyovers and flushed birds were excluded from the counts. An audio recorder was kept on hand, and field experts were consulted to confirm identification of unfamiliar bird calls. Researchers recorded GPS coordinates of points observed (Table 4), time of day, species, and number of individuals. (All tables are located in Appendix A). All data analysis was based on direct counts from the 10 survey points. We used the Shannon‐Wiener Index, H’ = ‐∑[(pi) × ln(pi)] to quantify diversity, and Pielou’s Index, J’ = H’/ H’max., to measure evenness for each site, for the two habitat types, and for the total study area. RESULTS AND DISCUSSION From 80 point count surveys, we identified 310 individuals of 37 different species (Appendix A). We also detected 4 more species incidentally: Cedar Waxwing (Bombycilla cedrorum), Common Ground Dove (Columbina passerine), Great Blue Heron (Ardea herodias), and Western Scrub‐jay (Aphelocoma californica). Over 63% of all individuals identified at point counts consisted of six species: Northern Cardinal (Cardinalis cardinalis), Baeolophus spp., Bewick’s Wren (Thryomanes bewickii), Mourning Dove (Zenaida macroura), Carolina Chickadee (Poecile carolinensis), and Ruby‐crowned Kinglet (Regulus calendula) (Appendix A). Cumulative analysis consisted of species richness, abundance, relative abundance, diversity, and evenness. Figure 3 shows the distribution of cumulative data. For each point, data analysis included species richness, abundance, relative abundance, diversity, and evenness (Fig. 4, 5). Species richness values varied from 6‐19 at points 6 and 8, respectively. The Golden‐cheeked Warbler (Setophaga chrysoparia), an endangered species in central Texas, was found at points 1, 3, and 10, all of which were forested areas. Evenness was lowest at point 7 10, with a value of 0.8469, and highest at point 6, with a value of 0.9435, closely followed by point 5, at 0.9415. Raw abundance values varied from 19 at point 6, to 87 at point eight. Species richness, abundance, relative abundance, diversity and evenness were calculated for each habitat type. In the grassland habitat 23 species were identified while 28 were identified in the woodland habitat. Abundance was also much higher in woodland habitat (188) than grassland habitat (122) as well as evenness (0.8638 and 0.6466, respectively) (Fig. 6). Figure 3. Cumulative abundance data of birds from all identifications and point counts. Abbreviations accepted by American Ornithological Union are listed in Appendix 1. Figure 4. Species richness estimates at each point. 8 Figure 5. Evenness estimates at each point Figure 6. Evenness, abundance, and species richness values in grassland and woodland habitats. Evenness values were multiplied by 100 to incorporate these variables into one figure. Bars reflect 95% confidence intervals. The most abundant bird species found on this property was the Northern Cardinal, making up 20.32% of all sightings, followed by Baeolophus spp. which made up 12.58% of all sightings (Table 3). The surprising part of this data however was the appearance of the endangered Golden‐cheeked Warbler making up 1.29% of all sightings (Table 3). It was unique to see several raptor species within 50 meters of our points; these included Turkey Vulture, Sharp‐shinned Hawk, Great Horned Owl, Red‐tailed 9 Hawk, and Red‐shouldered Hawk, each making up less than 1% of total sightings (Table 3). When we examined the abundance, richness, and evenness of species found in woodlands versus grassland habitats in Figure 5, all 3 indices were higher in woodland habitats. This could indicate that this is the preferred habitat for a large number of the bird species found on the BCI property. Point 8 was unique among the points in that it was the location of the Bracken Bat Cave entrance. This point can be considered, at least in part, edge habitat; it is shown also to have significantly higher species richness and abundance than the other points 10 HERPETOFAUNA Kristin Covert, Michelle Durfee, Jose Martinez, Ann McMaster, Sarah Reverman METHODS Sampling techniques employed consisted of using drift‐fence funnel traps, cover boards, and time constraint active searches with the use of stump rippers. Identification of herpetofauna was determined with the use of A Field Guide to Reptiles and Amphibians: Eastern and Central North America (Conant and Collins 1998). Drift‐Fence Funnel Trap. ‐ Drift‐fence funnel traps have been shown to be superior in overall trap success with lowest incidents of capture fatalities (Todd et al. 2007, Farallo et al. 2010). Combining drift‐fence funnel traps with large drift‐fence pit fall traps is the best practice for maximizing trap efficiency and yields (Todd et al. 2009; Farallo et al. 2010). Using these sampling techniques increases the potential of collecting fossorial, semifossorial and cryptic species (Todd et al.

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