FISH &WILDLIFE REFERENCE LIBRARY Technical Report #88-5-01 1987 DISTRIBUTION, STATUS, AND HABITAT AFFINITIES OF TOWNSEND'S BIG-EARED BAT (PLATOTUS TO WNSENDIT) IN okPdaN m Tr Oregon Department of Fish and Wildlife Nongame Wildlife Program DISTRIBUTION, STATUS, AND HABITAT AFFINITIES OF TOWNSEND'S BIG-EARED BAT (PLECOTUS TOWNSENDII) IN OREON J. Mark Perkins Consulting Wildlife Biologist Compiled with Connie Levesque Oregon Department of Fish and Wildlife Oregon Department of Fish and Wildlife Nongame Wildlife Program Technical Report #86-5-01 1987 CONTENTS P age FIGURES ............................................................... iii TABLES iv ................................................................ ABSTRACT 1 .............................................................. INTRODUCTION 1 .............................. .................... ...... STUDY AREA 2 ............................................................ METHODS 3 ...................................... ........................ 3 Winter Surveys ; .................. ................................ Summer Surveys 3 ................................................... RESULTS 6 ............................................................... 6 Winter Surveys ................................................... Summer Surveys 10 Roost Sites...................................................and Nursery Colonies 10 Mist Net ............................ 11 Sites .............................................. Museum Searches 17 ...................................... ........... Statewide Distribution 17 Summary of Distribution........................................... 17 Comparison of ..................................Records _ 17 Distribution .......................... DISCUSSION 27 ............................................................ Requirements 27 Habitat ............................................. Size and 28 Population Status ..... ............................... MANAGEMENT RECOMMENDATIONS 31 ............................................ General Recommendations 31 Habitat Protection .......................................... 31 Population Monitoring...... ................................... 32 Education and Recovery.......................................Programs 32 ............................. Site-specific Recommendations 32 . .................................... U.S. Forest ervi ce 33 Bureau of Land Management......................................... 37 Private/State/Other .................. ................ 39 ......................................... ACKNOWLEDGMENTS 42 ................ ...................................... REFERENCES 43 ........................................... ................ i CONTENTS (continued) Page APPENDICES 45 ............................................................ Appendix A: Sources used to determine potential bat 46 hibernacula in central Oregon I ............... ..... Appendix B: Museuins visited or contracted for additional bat 47 records ....................................... Appendix C: Habitat types and definitions used for mist 48 net inventories ................................... Appendix D: Availability of maps for caves containing bat hibernacula and colonies 50 roosts, nursery .......... FIGURES Number Page 1. Study areas surveyed for Townsend's Big-eared bats in Oregon between 1982 and 1986 4 ............................................ 2. Known of Townsend's in Oregon 19 distribution big-eared bat ......... TABLES Number Page 1. Chronology of areas surveyed for Townsend's big-eared bat by Perkins between 1982 and 1986 5 .................................... 2. Nufuber of sites successfully searched lor nilbernacula of Townsend's big-eared bat ........................................ 7 3. Bat species found during hibernacula searches between 1982 and 1986 7 .................................................... 4. Hibernacula of Townsend's big-eared bat found between 1982 and 1986 by 8 county ............................................... 5. Number of sites successfully searched for summer roosts and of Townsend's 10 nursery colonies big-eared bat ................. 6. Bat species found during summer roost and nursery colony between 1982 and 1986 12 searches ............................ 7. Nursery colonies of Townsend's big-eared bat found between 1982 and 1986 by 13 county .......................................... S. Mon-nursery day and night roosts found for Townsend's between 1982 and 1986 by 14 big-eared bat county .................... 9. Number of Townsend's big-eared bats found at summer roost sites and nursery colonies between 1982 and 1986 .................. 15 10. Number of sites successfully mist netted for Townsend's between 1982 and 1986 15 big-eared bat .............................. 11. Number of bats captured at summer mist net sites by 16 species ....................................................... 12. Mist net sites for Townsend's big-eared bat between 1982 and 1986 by 17 county ............................................... 13. Previously unreported museum records for Townsend's in Oregon 18 big-eared bat .......................................... 14. Statewide distribution records for Townsend's big-eared bat in Oregon 20 ........................................................ 15. Comparison of historical and present winter records Townsend's in Oregon 27 of big-eared bat central .................... iv DISTRIBUTION, STATUS, AND HABITAT AFFINITIES OF TOWNSEND'S BIG-EARED BAT (PLECOTUS TOWNSENDII) IN ORECO-N' J. Mark Perkins ABSTRACT A five-year survey of the distribution, status, and habitat affinities of Townsend's big-eared bat (Plecotus townsendii) in Oregon was conducted between 1982-7n-d [email protected], mines, bridges, and buildings were surveyed for winter hibernacula, summer nursery colonies, and day or night roosting bats. Water sites and cave or mine entrances were mist netted to identify areas of bat activity. Townsend's big-eared bats were found at 34 hibernacula and accounted for approximately 997 (94%) of the 1,062 bats found wintering in Oregon. Nine nursery colonies with about 970 Townsend's big-eared bats and 22 summer roost sites with 43 bats were found in the study area. Only six Townsend's big-eared bats were mist netted. Caves and cave-like structures, which provide critical habitat for hibernacula and nursery colonies of Townsend's big-eared bats in Oregon, are increasingly subjected to disturbance from recreational use and vandalism. Townsend's big-eared bats were not found or had greatly reduced numbers at many historic sites in Oregon. Critical hibernacula and nursery colonies for Townsend's big-eared bat are defined, and statewide distribution records are summarized. Management recommendations include habitat protection, population monitoring, and education of the public as well as federal and state land management personnel. INTRODUCTION The general ecology and distribution of bat species in Oregon was summarized by Maser and Cross (1981) and Maser et al. (1981). Cross (1976), restricted his bat survey to southern Oregon. Specific information is lacking on the current status, distribution and management guidelines of bat species in Oregon. This information is needed for state and federal agencies to maintain viable bat populations. In March 1982, a five-year study was initiated by the Oregon Department of Fish and Wildlife through the Nongame Wildlife Program, to inventory those portions of Oregon not previously surveyed for bats by Cross (1976). The study objectives were to: 1. Determine the distribution of each bat species occurring in Oregon; 2. Determine comparative population levels of e ach species in Oregon; 3. Determine, if possible, habitat(s) necessary for viable populations of each species; 4. Locate critical reproductive, hibernating, and feeding sites; 5. Collect potentially useful ecological data; and 6. Develop management recommendations for each species and for critical. sites. This report summarizes information on the Townsend's big-eared bat (Plecotus townsendii) from the survey conducted between 1982 and 1986, the work of Cross (1976), Maser and Cross (1981), and additional museum specimens. Hall (1981) recognizes two subspecies of Townsend's big-eared bat. P. t. townsendii is found west of the Cascade Mountains in Oregon; P. t. ingens occurs east of the Cascade Range. Maser and Cross (1981) recognize I one subspecies - P. t. townsendii. have encountered at least two distinct color phases, but am reluctant to recognize subspecies on this basis alone. In 1985, Townsend's big-eared bat (P. t. townsendii) was designated a federal candidate species (category 2) by the U.S. Fish and Wildlife Service (U.S. Fish and Wildlife Service 1985). This report provides statewide distribution records for this sensitive species, defines critical hibernacula and maternity colony sites, and recommends management guidelines to prevent further population declines of the Townsend's big-eared bat in Oregon. STUDY AREA The study area consisted of potential bat habitat throughout the State of Oregon, excluding the portions of southern Oregon surveyed by Cross (1976), with the exception of two limestone caves in Josephine County and a cave in -2- the southern portion of Malheur County (Figure 1). The state was inventoried over broad geographic areas between 1982 and 1986 as shown in Table 1. METHODS To inventory Townsend's biq-eared bat. suitable habitat was identified as existing caves and mines. Barbour and Davis (1969) considered Townsend's big-eared