BAT RESEARCH NEWS VOLUME 46: No. 1 SPRING 2005 BAT RESEARCH NEWS Volume 46: Numbers 1–4 2005 Publisher and Managing Editor: Dr. Margaret A. Griffiths, CB 257, 700 College Place, Lycoming College, Williamsport PA 17701; TEL 570-321-4399, FAX 570-321-4073; E-mail: [email protected] OR [email protected] Editor for Feature Articles: Dr. Allen Kurta, Dept. of Biology, Eastern Michigan University, Ypsilanti MI 48197; TEL 734-487-1174, FAX 734-487-9235; E-mail: [email protected] Editor for Recent Literature: Dr. Karry Kazial, Dept. of Biology, SUNY at Fredonia, Fredonia, NY 14063, TEL 716-673-3284, FAX 716-673-3493; E-mail: [email protected] Editor for Conservation/Education: Patricia A. Morton, The Nature Conservancy, Mukwonago River Watershed Project Director, N8957 Pickerel Jay Road, East Troy WI 53120; TEL 262-642-7276; E-mail: [email protected] Emeritus Editor: Dr. G. Roy Horst Copyright 2005 Bat Research News. All rights reserved. This material is protected by copyright and may not be reproduced, transmitted, posted on a Web site or a listserve, or disseminated in any form or by any means without prior written permission from the Publisher, Dr. Margaret A. Griffiths. The material is for individual use only. Bat Research News is ISSN # 0005-6227. BAT RESEARCH NEWS Table of Contents for Volume 46, 2005 Volume 46: Number 1, Spring 2005 i Volume 46: Number 2, Summer 2005 Volume 46: Number 3, Fall 2005 ii Volume 46: Number 4, Winter 2005 iii BAT RESEARCH NEWS VOLUME 46: No. 1 Spring 2005 Table of Contents The Use of Bat Gates at Abandoned Mines in Colorado Kirk W. Navo and Paul Krabacher . 1 Long-term Fidelity by Tree-roosting Bats to a Home Area Lisa Winhold, Emily Hough, and Allen Kurta . 9 An Inexpensive, Mobile Antenna Tower for Radio-telemetry Timothy C. Carter . 11 Recent Literature Compiled by Karry Kazial . 17 News from the Czech Republic: The 70th Birthday of Professor Jirí Gaisler, D.Sc. Zdenek Rehák and Jan Zukal . 35 In Memory: Eugene H. Studier Dennis P. Viele. 37 Future Meetings and Events Compiled by Margaret A. Griffiths . 43 Front Cover The front cover illustration is a portrait of Antrozous pallidus by Fiona Reid of Toronto, ON. This drawing of the pallid bat is copyrighted by the artist, and is used with her generous permission. Thank you, Fiona. The Use of Bat Gates at Abandoned Mines in Colorado Kirk W. Navo1 and Paul Krabacher2 1Colorado Division of Wildlife, 722 S. Rd 1E, Monte Vista, CO 81144;and 2Colorado Division of Minerals and Geology, Grand Junction, CO 81505 E-mail: [email protected] and [email protected] Introduction Availability of roosts affects the distribution and viability of most nearctic populations of bats (Humphrey, 1975; Pierson, 1998). Bats find suitable roosting habitat in various natural and man-made features, including trees, rock crevices, caves, buildings, and mines. Subterranean roosts are used occasionally by many species, but some species are dependent on these features for all or some of their seasonal roosting requirements (e.g., Humphrey and Kunz, 1976; Kunz and Martin, 1982). Abandoned mines often serve as surrogates for caves and recently have received attention in efforts aimed at bat conservation (Navo et al., 1991; Riddle, 1995; Tuttle and Taylor, 1998; Vories and Throgmorton, 2000). One tool available to resource managers for protection of caves and mines is a “gate” (Currie, 2002; Vories et al., 2002), which restricts access by humans and eliminates disturbance to roosting bats. Gates, when properly designed and constructed, can aid in the recovery of bat populations at formerly impacted roosts (Richter et al., 1993). However, improperly designed gates can have negative impacts on bats, including abandonment of roosts (Tuttle 1977) and alteration of internal microclimate (Currie, 2002; Richter et al., 1993). Additionally, bat gates may alter normal patterns of flight at cave entrances or increase predation (Hammer and Arlettaz, 1998; Ludlow and Gore, 2000; Tuttle, 1977; White and Seginak, 1987). Gate designs have changed over the years to increase their resistance to vandalism and reduce impacts to air movement and subsequent modification of internal temperature (Currie, 2002). Current designs are used successfully at some North American caves and mines that harbor large colonies of bats, such as gray bats (Myotis grisescens) and Indiana bats (Myotis sodalis), but their construction can be expensive and difficult to justify with smaller colonies or species not known to be endangered or declining. In some western states, bats often use abandoned mines, but colonies typically are smaller (Sherwin et al., 2000a, 2000b; Sherwin et al., 2003) than those in the East (Currie, 2002; Ducummon, 2000). Resource managers, with limited funds and many pressing issues, need alternative designs to aid in conservation of bat roosts at abandoned mines in the West. However, it is important to include a monitoring program with implementation of new designs to evaluate the effectiveness of the design and resultant success of the conservation action (Currie, 2000; Burghardt, 2000). In Colorado, protection of bat roosts in abandoned mines began in 1990 (Navo et al., 1991). Species using abandoned mines in Colorado include Antrozous pallidus, Corynorhinus townsendii, Eptesicus fuscus, Myotis lucifugus, M. volans, M. evotis, M. thysanodes, M. ciliolabrum, M. californicus, Pipistrellus hesperus, and Tadarida brasiliensis. The focus of gating efforts, however, is C. townsendii, a species that is declining over much of its range (Perkins, 1985; Pierson et al., 1999). To reduce the cost of gates and increase the number of mines that are protected, modifications of standard designs were developed and installed during mine reclamation activity from 1991 to 2004. Herein, we report the results of 13 years of post- 1 2 Bat Research News Volume 46: No. 1 construction monitoring on these designs and their implications for conservation of bat roosts in abandoned mines of the West. Methods We evaluated four types of gate—full gates, ladder gates, culverts with full gates, and culverts with ladder gates (Fig. 1)—mostly at sites with evidence of use by C. townsendii. Full gates are the traditional design and provide for passage of bats across the entire gate (Vories et al., 2002). Some full gates were constructed of flat iron bars instead of the standard angle iron. The ladder design (Navo and Krabacher, 2002) was similar to that reported in Pierson et al. (1991), with the center of the gate designed to allow bat passage and the sides allowing airflow only. The entire gate was welded to steel anchors secured into the surrounding bedrock. Occasionally, the ribs (sides) of a mine were weathered or otherwise too unstable for anchoring the gate, and in these cases, a steel culvert (<6 m in length) was placed in the portal; the gate then was welded to the culvert, or mortared rock walls were keyed into the sides to provide a secure anchoring for the gate. These “wing walls” did not interfere with airflow, because the face of the walls was at the excavated side of the adit and did not constrict the opening of the mine. Spacing between bars in a full gate or the center of a ladder gate was 15 cm (6 inches). Gated mines were located throughout central and western Colorado. Elevation of the mines ranged from ca. 1,750 to 3,600 m, and surrounding forests included pinyon-juniper, ponderosa pine, mixed conifer, and spruce-fir woodlands; most mines were in pinyon- juniper/desert shrub or mixed conifer habitats. Four types of bat-friendly closures were monitored, including 28 ladder gates, 8 full gates, 6 culverts with ladder gates, and 5 culverts with full gates. Our post-gating surveys documented only whether or not bats were using the mines and not whether the size of the population changed after gating. Surveys were conducted using a variety of techniques, including capture of bats at entrances, internal surveys, and passive monitoring. Surveys at the portal of a gated mine involved harp traps and were intended to document use of a gate by the capture of bats going in or out of the mine; all captured bats were identified to species, aged, sexed, and released. Internal surveys involved actually entering a gated mine to document roosting bats and followed standard safety guidelines (Altenbach, 1995; Navo, 2001). Most passive surveys used video cameras (Sony, Handycam Nightshot Digital 8, DCR-TRV120; Sony Corp. of America, New York, New York), but as an additional evaluation for some ladder gates, an infrared motion detector (Trailmaster 1500, Goodson & Associates, Inc., Lenexa, Kansas) was installed on the inside to document passage of bats. Number of surveys conducted at a single mine ranged from one to ten, and some sites were monitored using multiple methods. Time between pre- and post-gating surveys was 1–12 years. Average time between installation and initial evaluation was 1.6 ± 0.2 (SE) years and ranged from <1 to 5 years. Results During 13 years of reclamation activities, 330 gates were installed at 295 mines. We selected 47 mines for 89 post-gating surveys that occurred from June 1992 to July 2004. Post- gating monitoring consisted of 58 capture surveys, 22 internal surveys, and 9 video surveys; in addition, use of five mines was further evaluated with a motion detector. We documented Spring 2005 Bat Research News 3 A B C D C Figure 1. Styles of gate used at mines in Colorado. A) ladder, B) culvert with ladder, C) full, and D) culvert with full. continued use by bats at 43 mines (91%; Table 1), and of the four mines at which we failed to document bat use, three received only one post-gating survey.