Bat Inventory
Importance / IssuesAs secretive, mobile, and nocturnal animals, bats are often under represented in native wildlife inventories. The life histories of many species of bats are poorly understood, yet their longevity, low reproductive rates, and strong habitat preferences suggest they may be potential indicator species in landscapes. Regional and continent-wide declines in bat populations have heightened attention for these species (Verts and Caraway 1998). The causes attributed to bat declines include loss of roosting habitat, natural habitat changes, and environmental contaminants. Due to their low reproductive rates, bats appear to be highly sensitive to disturbances which impact roosting habitat or affect reproductive success (Hayes in prep). Even short-term human disturbance may cause some species of bats to vacate optimal roosting or hibernation sites (hibernacula) for less suitable habitat. Detailed data on species presence, roosting sites or hibernacula, and populations are considered essential management information in the Klamath parks. Diverse life histories and habitat needs have hampered definitive analysis of population trends for many bat species. Colonial roosting bats associated with caves have been the focus of most bat monitoring in the parks, and there has been an ongoing monitoring effort for cave-roosting bat colonies in LABE and ORCA. Over dispersed species, which roost singly or in small groups across the landscape, are much less poorly known. Basic information on status and trends of most species is so inadequate that scientists are presently unable to document or predict species population declines, or to direct management. |
 ObjectivesThe primary objective of this inventory is to document the full bat fauna of each park as cost-effectively as possible. The second objective is to inventory likely habitats and locate new populations of species in the parks to support future monitoring efforts. ParksCrater Lake National Park Project StatusCompleted Principal InvestigatorsDr. Tom Morrell Andrew Duff |
ReportsDuff, Andrew. 2005. Investigator's Annual Report - Crater Lake National Park Duff, Andrew. 2005. Investigator's Annual Report - Oregon Caves National Monument Duff, Andrew. 2005. Investigator's Annual Report - Redwood National and State Parks | |
ResultsCrater Lake National Park 119 bats representing six species were captured in mist nets during 24 nights (10,339 m2 net hours of netting effort). Three species represented 68.1% of my mist net captures: silver-haired bats (26.1%), long-eared myotis (21.0%), and long-legged myotis (21.0%). The remaining 31.9% of captures consisted of Yuma myotis (16.0%), little brown myotis (11.8%), and big brown bats (4.1%). Long-eared myotis and Yuma myotis appeared to be the most widespread species being captured at 6 (60%) sites. Silver-haired bats were captured at 4 (40%) sites. Most (87.4%) of my captures were males. Anabat sequence files were recorded at 19 sites during 80 nights. Three species or species groups represented 93.4% of the activity. Forty kHz myotis (long-legged myotis and little brown myotis), provided the highest bat activity, long-eared myotis provided the second highest activity (11.6%), followed by 50 kHz myotis (California myotis and Yuma myotis) (11.3%). The remaining 6.6% of activity was represented by big brown bats (2.4%), silver-haired bats (1.8%), hoary bats (0.3%), Mexican free-tailed bats (0.06%), and California myotis (0.01%). Eagle Lake Ranger District 2,043 bats representing 14 species were captured in mist nets during 76 nights (39,377 m2 net hours of netting effort). Five species accounted for 82% of the captures: silver-haired bat (19.8%), long-eared myotis (18.2%), little brown bat (16.8%), big brown bat (26.8%), long-legged myotis (14.4%), and Yuma myotis (13.5%). The remaining 18% of the captures included bid brown bat (7.1%), fringed myotis (3.0%), California myotis (2.2%), pallid bat (2.1%), hoary bat (1.4%), small-footed myotis (0.5%), Townsend's Big-eared bat (0.1%), Mexican free-tailed bat (0.1%), and western red bats (0.05%). The remaining 11.2% of the captures included: pallid bat (4.7%), long-eared myotis (3.2%), western red bat (2.0%), hoary bat (1.2%), and fringed myotis (0.7%). Lassen Volcanic National Park 338 bats representing eight species were captured in mist nets during 54 nights (28,904 m2 net hours of netting effort). Five species accounted for 88.0% of the captures: long-eared myotis (26.5%), Yuma myotis (19.7%), little brown bat (19.7%), long-legged myotis (14.4%), and big brown bats (7.0%). The remaining 12.0% of the captures included: silver-haired bats (5.9%), hoary bats (4.4%), and fringed myotis (2.4%). Oregon Caves National Monument Five bats representing four species were captured during 3 nights (343.2 m2 net hours of netting effort in mist nets and 9.75 m2 harp hours of effort). The two focal sites, Monument Deep and High Hopes, were acoustically surveyed during mid September. At Monument Deep, an average of 32.5 Anabat sequence files were recorded at the gated opening and an average of 35.3 were recorded at non-gated openings. At High Hopes, an average of 30 sequence files were recorded at gated openings and 12.5 sequence files were recorded at non-gated openings. Additionally, at the 110 cave entrance, 87 sequence files were recorded without the tarp deployed and 80 sequence files were recorded with a tarp covering approximately one-half of the bat-friendly gate. Long-eared myotis was the most commonly captured bat (40.0%), followed by Townsend’s big eared bat (Corynorhinus townsendii) (20.0%), California myotis (20.0%), and fringed myotis (20.0%). At ORCA, 100.0% of my captures were males. All of my bat captures came from harp traps; unfortunately I was unsuccessful capturing bats at the upper chalet pond using mist nets during two attempts. Redwood National and State Parks77 bats representing nine species were captured in mist nets during 25 nights (12,270 m2 net hours of netting effort). Two species represented 77.3% of mist net captures, Yuma myotis (49.4%) and silver-haired bats (27.9%). The remaining 22.7% of the captures consisted of seven species: California myotis (7.5%), big brown bats (5.1%), little brown bats (3.8%), hoary bats (2.4%), long-legged myotis (1.3%), Townsend’s big-eared bats (1.3%), and pallid bats (Antrozous pallidus) (1.3%). Males represented 58.4% of the captures. No bats were captured at two sites: Tall Trees Grove on Redwood Creek and the pool near the Miner’s Ridge trailhead. In addition to the captures made at other sites, five Townsend’s big-eared bats were observed in the northern most building at the World War II Radar Station in September 2004. In addition to live capture techniques, I recorded Anabat sequence files at 20 sites during 57 nights. At REDW, 96.8% of the activity during the first 2.5 hours of the night was represented by the two myotis species groups. Fifty kHz myotis provided the highest bat activity (71.1%), and forty kHz myotis provided the second highest activity (25.7). The remaining 4.2% of activity was represented by silver-haired bats (1.3%), hoary bats (0.5%), big brown bats (0.3%), long-eared myotis (0.2%), Mexican free-tailed bats (0.02%), and fringed myotis (0.02%). Based upon the Anabat data collected during the first 2.5 hours of the night, 40 and 50 kHz myotis were most widespread, being documented at 19 (95.0%) sites. Big brown bats were documented at 6 (30.0%) sites. Whiskeytown National Recreation Area 403 bats representing ten species were captured in mist nets during 77 nights (31,760 square meter net hours of netting effort). Five species accounted for 89% of the captures: Yuma myotis (27.8%), big brown bat (26.8%), silver-haired bat (12.9%), California myotis (11.2%), and Mexican free-tailed bat (10.2%). The remaining 11.2% of the captures included: pallid bat (4.7%), long-eared myotis (3.2%), western red bat (2.0%), hoary bat (1.2%), and fringed myotis (0.7%). |
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