Effect of gate installation on continued use by bats of four abandoned mine workings in western Montana

Effect of Gate Installation

on Continued Use by Bats

of Four Abandoned Mine

Workings in

Western Montana

A Report to:

Montana Department of Environmental Quality
Mine Waste Cleanup Bureau

2209 Phoenix Avenue
Helena, Montana 59620-0901

Submitted by:
Paul Hendricks

December, 1999

MONTANA

Natural Heritage
Program

599.41518
N11EGI
- 1999
1

^»fLb(Lc.l

Montana State Library

3 0864 1004 6971 0

ox aanssi

EFFECT OF GATE INSTALLATION

ON CONTINUED USE BY BATS

OF FOUR ABANDONED MINE WORKINGS

IN WESTERN MONTANA

December 1999

° 1999 Montana Natural Heritage Program

State Library Building, P.O. Box 201800, 1515 East Sixth Avenue. Helena, MT 59620-1800. 406-444-3009

This document should be cited as follows:

Hendricks, P. 1999. Effect of gate installation on continued use by bats of tour abandoned mine workings in western
Montana. Unpublished report to Montana Department of Environmental Quality. Montana Natural Heritage Program.
Helena. 13 pp.

ACKNOWLEDGMENTS

This project was funded by the Montana Department of Environmental Quality, Mine
Waste Cleanup Bureau, under DEQ Contract No. 480008 to the Montana Natural Heritage
Program, Natural Resources Information System, Montana State Library. Special thanks to Jack
Yates (DEQ) for his continued support of this work, to Lee Flath (Lewis and Clark Caverns State
Park) for his cooperation and interest in the project, and to Marian and Max Johnson of Ravalli
for permission to access the McDonald Mine. Tom O'Shea (USGS-Biological Resources
Division) kindly loaned the data loggers used during this project. Sam Martinez helped with the
surveys and recorded climate data during them.

INTRODUCTION

In 1996 the Mine Waste Cleanup Bureau of the Montana Department of Environmental
Quality installed culvert gate systems in the portals of four abandoned mine adits in western
Montana Two gates were installed at the McDonald ("Ravalli") Mine adits in Lake County, and
two more were placed in portals at the Gypsum Mine workings of Lewis and Clark Caverns State
Park in Jefferson County Inspection of these mine adits prior to gate installation revealed that
each was used at some time during the year by bats, particularly Townsend's Big-eared Bat
(Connor hi mis townsendii), a U.S. Fish and Wildlife Service species of special concern (Harvey
et al 1999)

Gates were installed to allow for continued use of each mine working by bats while
prohibiting accidental livestock entry and unauthorized access by humans. Gates were built with
13 mm rebar attached to an angle iron gate frame, using recommended vetical spacing at least
5.75 inches and horizontal spacing at least 24 inches (Turtle and Taylor 1994, Dalton and Dalton
1995) The gate itself was attached to a corrugated metal pipe that was inserted into the mine
portal, surrounding the pipe with fill to assure that entry into the mine was through the pipe and
gate, the gate was secured with a protected padlock Although the gate design was supposed to
be bat-friendly, no follow-up study had been conducted at any of the sites to determine if bats
were still using the sites after gates were in place

The objectives of the work described in this report were two-fold. First, determine the
effectiveness of the gate design in its primary function of allowing continued access by bats to
the mine workings Second, gather mine environment data (temperature, relative humidity)
continuously over a several month period to aid in characterization of the mine environments
where bats occurred

STUDY SITES AND METHODS

The McDonald ("Ravalli") Mine is just west of the small community of Ravalli, in Lake
County. T18NR20WS3 1NWNE at about 853 m (2800 ft) elevation near the Jocko River and at
the southern boundary of the National Bison Range The mine includes three open adits that
produced crude copper ore, the lower two of which are now gated The mine has not been
worked since 1917 (Rossillon 1995)

The Gypsum Mine lies within the boundary of Lewis and Clark Caverns State Park, in
Jefferson County, about 275-305 m (900-1000 ft) elevation below the mouth of the cave, and
overlooking the Jefferson River The mine is part of a 1 18-acre claim patented in 1915 that
includes a number of prospects, a large open pit, and a couple of adits The two gated adits are
in T1NR2W in S21NWNW (adit #1) and S20NENE (adit #2), at about 1432 m (4700 ft) and
1390 m (4560 ft) elevation, respectively

During mine surveys, all bats encountered were recorded and identified to species, if
possible, taking care not to disturb the bats Location of bats within the mine was noted, and a
series of temperature and relative humidity measurements were made with a Bacharach sling
psychrometer Mines were explored to the fullest extent possible, which depended in part on
underground configuration and relative hazard At least one electronic data logger (HOBO,
Onset Computer Corporation, Bourne. MA) was installed in each working, usually within the
area occupied by bats Data loggers, set to record temperature and relative humidity every 6

hours, were attached to extendable aluminum poles (Mr. Longarm, Inc., Greenwood, MO) using
duct tape, and positioned to within 40 cm of the ceiling (ca. 1.4 to 2.0 m above ground).
Location of data loggers relative to portals was documented; data loggers were left in mines for
6-7 months before retrieval. Data loggers in the McDonald Mine adits were installed on 7
December 1998 and retrieved on 13 July 1999. At the Gypsum Mine, data loggers were installed
on 6 January 1999 and retrieved 13 July 1999. Summary Figures portraying data logger results
are presented at the end of this report.

RESULTS

McDonald Mine Sites. On 7 December (13: 10-16:30 MST), the two (east and west) gated adits
were entered and data loggers installed. In the East Adit, 8 hibernating Townsend's Big-eared
Bats (Corynorhinus townsendii) were found on the walls of the entrance hallway in the first 39.7
m (130 ft) beyond the gate. A data logger ("shallow") was placed at this point 39.7 m from the
portal, where the main passage angles sharply to the west (left). A second data logger ("deep")
was placed 106.7 m (350 ft) from the portal in this west-trending passage, shortly before the
workings open into a large room ascending to at least one additional level. No bats were found
in this section of the mine on the December survey, and the second level beyond the large room
were not checked. On the 1 3 July survey, a single unidentified Myotis flew from the entrance
when it was entered (08: 17) but no additional bats were present in the first part of the mine. One
Townsend's Big-eared Bat was seen flying in the upper parts of the large room. It is possible
other bats were present in this portion of the mine.

In the West Adit no bats were found during the 7 December survey. This working was
surveyed entirely (about 50 m; 164 ft), and a data logger was left where the main haulway angles
sharply to the east, 12.7 m (41.7 ft) from the entrance. On the 13 July survey, a single
Townsend's Big-eared Bat flew from the entrance area and a nursery colony of 20-25 individuals
was found clustered tightly on the wall of the east-trending passage near its juncture with the
entrance passage, about 2.0 m (6 5 ft) beyond the data logger.

The upper ungated adit was surveyed on 7 December; no bats were found. The working
is relatively shallow, extending 17.1m (56 ft) beyond the portal.

Climate data from the lower gated adits (Table 1, Figures 1-6) show all workings were
relatively cool during the recording period (8 December 1998 to 13 July 1999). Temperature

TABLE 1. Maximum and minimum electronic data logger values for temperature (°C) and relative
humidity (RH; %) at the McDonald Mine sacs (8 December 1998 to 13 July 1999) and Gypsum Mine sites (7
January 1999 to 13 July 1999).

Mine Working

Ele\ (m)

Max. Temp

Min. Temp.

Max. RH

Min. RH

McDonald East (shallow)

853

11.1

-0.2

100

28.1

McDonald East (deep)

853

11.9

7.9

100

89.5

McDonald West

853

15.0

9.1

97.8

59.0

Gypsum #1 (upper)

1432

~

-

-

-

Gypsum #2 (lower)

1390

7.1

0.3

989

71.1

varied by 12°C (20°F) 39.7 m from the portal in the East Adit during this period. The range was
6°C (10.4°F) 12.7 m from the portal in the West Adit, and only 3.5°C (6.1°F) deep in the East

Adit 106 7 m from the portal Maximum temperatures were recorded during the first two weeks
of July in each adit, minimum temperatures were recorded on 21-22 December 1998 (see Figures
1. 3, 5) The pattern of variation in relative humidity among adits was identical to the pattern for
temperature Relative humidity varied by 81 9% at the shallow location in the East Adit (Figure
2). but only by 10 .5° o at the deep location (Figure 4, Table 1 ) In the West Adit, relative
humidity varied by 38.8% during the sample period (Figure 6) Maximum values occurred on a
range of dates in each adit, from 29 January until July deep in the West Adit and between 5 May
and July shallow in the same adit, to a shorter period ( 1 8 June to 6 July) in the West adit
Minimum relative humidity was recorded on 21 December in the East Adit, but on 13 July in the
West Adit

Gypsum Mine Sites. The two gated Gypsum Mine adits (#1 "upper" and #2 "lower") were
surveyed completely on 6 January 1999, when a single data logger was installed in each The
upper Adit #1 extends straight back for 22 4 m (73.5 ft) from the portal, the lower Adit #2
extends straight back for 44 0 m ( 144 4 ft) In Adit #1, one Townsend's Big-eared Bat was
hibernating 1 m (3.3 ft) above the floor 5 8 m (19 0 ft) from the drift face. In Adit #2, one
unidentified Myotis (probably the Little Brown Bat A/, lucifugus) was found hibernating wedged
in a crack about 5 0 m (16.5 ft) from the portal, four Townsend's Big-eared Bats were
hibernating between 3 4 and 8.0 m (1 1.2 and 26 2 ft) from the portal Three additional
Townsend's Big-eared Bats were hibernating about 25 5 m (83 7 ft) from the portal No bats
were observed in either adit when data loggers were retrieved on 13 July 1999

In Adit n\ a data logger was installed where the lone bat was hibernating 5 8m from the
drift face Unfortunately, this data logger failed to record any data during the recording period (7
January to 13 July 1999) However, at the time the data logger was installed, temperature in this
adit ranged from 3.9-6 4°C (39-43 5°F), the warmest value about 3 m (9 8 ft) from the drift face,
relative humidity was 53% 1 2 6 m (4 1 3 ft) from the portal to the drift face In Adit #2 a data
logger was installed 8 m (26.2 ft) from the portal (36 m from the drift face), at the far end of the
primary zone of bat occupancy At this location mine temperature varied by 6 8°C (12 2°F) in 6
months, relative humidity varied by 27 8% (Table 1 ) Maximum temperature and relative
humidity (Table 1 , Figure 7 and 8, respectively) were recorded in the first part of July, just prior
to data logger retrieval, minimum values for each variable were recorded on 24 January

DISCUSSION

Workings at both mine sites were gated because they were known to harbor bats in
winter Townsend's Big-eared Bat (( 'orynorhmus townsendii) has been known to occupy the
McDonald Mine workings since at least 1965 (specimens UMZ9942 through UMZ9945,
collected 5-6 December, P L Wright Vertebrate Museum, University of Montana) More
recently the three adits of this mine were surveyed on 6 November 1996 Five hibernating
Townsend's Big-eared bats were present in the East Adit (20-61 m from the portal) and another
was activelv thing, no bats were present in the West Adit One fresh dead big-eared bat was
found in the upper adit as was one active individual, probably the same active bat in the East
Adit Use of the Gypsum Mine adits is less well-documented, but bat activity in and around
Lewis and Clark Caverns has been reported for many decades (Lee Flath, pers comm )

The surveys reported here indicate continued use of all gated mine workings by bats,
certainly an encouraging finding that indicates the gate design in use is. indeed, bat friendly

Furthermore, the number of bats present (8) at the McDonald Mine adits on 7 December 1998
was nearly identical to the number (7) found in the same portion of workings surveyed on 6
November 1996, just prior to gate installation. This further supports the idea that the gating had
little impact on the attractiveness of these mine workings to bats.

The West Adit of the McDonald Mine appears to be used mostly as a maternity site,
whereas the East Adit is used as a hibernaculum. The West Adit was warmest with the least
humidity, both of which promote more rapid development of young (Humphrey and Kunz 1976).
The McDonald East Adit and the two Gypsum Mine adits provide conditions suitable for use as
hibernacula by Townsend's Big-eared Bat: temperatures < 10°C but above freezing with high
relative humidity (Table 1, Figures 1-8). High relative humidity reduces water loss and
desiccation while bats are inactive, low temperature reduces metabolic costs and use of fat stores.
The temperature values are similar to those reported for big-eared bat hibernacula in northern
California (Pierson et al. 1991), Idaho (Genter 1986), Kansas (Twente 1955), and Oklahoma
(Humprey and Kunz 1976), but not as warm as in other parts of its range (summary in Webb et
al. 1996).

RECOMMENDATIONS

1) The gate design at the McDonald and Gypsum mines is bat friendly and works. Continue
using this design where appropriate at other adits as additional abandoned mines are
reclaimed.

2) Other gate designs have been installed by the state on abandoned mine workings elsewhere in
Montana that are not effective in preventing unauthorized human entry. Some of these
designs, using brick walls that may alter airflow, could also alter mine environments and
affect their suitability as hibernacula or maternity roosts (Richter et al. 1993). Consider
replacing these with the current design, especially at sites where use by bats has been
documented.

3) Continue monitoring bat use at the McDonald and Gypsum mines. Both sites are ideal for
long-term monitoring of a bat species of special concern, and provide both hibernacula and
maternity roosts. Monitoring could include multiple visits (every other month) by qualified
bat biologists to document timing of occupancy and location in each working throughout the
year; special care must be taken to minimize disturbance of bats if monitoring is done this
frequently. However, these data will provide a better understanding of roost requirements
that may help determine the suitability or lack of suitability of other abandoned mines, and
aid in decisions to close or gate other sites.

LITERATURE CITED

Dalton, D. C, and V. M. Dalton. 1995. Mine closure methods including a recommended gate
design. Pp. 130-135 in Riddle, B. R. (ed). Inactive mines as bat habitat: guidelines for
research, survey, monitoring and mine management in Nevada. Biological Resources
Research Center, University of Nevado, Reno.

Genter, D. L. 1986. Wintering bats of the Upper Snake River Plain: occurrence in lava-tube
caves. Great Basin Naturalist 46:241-244.

Harvey, M J , J S Altenbach, and T L Best 1999 Bats of the United States. Arkansas Game
& Fish Commission, and the U S Fish and Wildlife Service 64 pp

Humphrey, S R , and T H Kunz 1976 Ecology of a Pleistocene relict, the Western Big-eared
Bat {Plecotus townsendii), in the southern Great Plains Journal of Mammalogy 57:470-
494

Pierson, E D , W E Rainey, and D M Koontz 1991 Bats and mines: experimental mitigation
for Townsend's Big-eared Bat at the McLaughlin Mine in California Pp. 3 1-42 in
Proceedings V: Issues and technology in the management of impacted wildlife Thome
Ecological Institute, Boulder, CO.

Rjchter, A R., S R Humphrey, J B Cope, and V. Brack, Jr 1993 Modified cave entrances
thermal effect on body mass and resulting decline of endangered Indiana Bats (Myotis
sodalis) Conservation Biology 7:407-415

Rossillon, M. 1995. The McDonald Mine, west of Ravalli: a cultural resource inventory and
evaluation Renewable Technologies, Inc., Butte, MT. Unpublished report. 24 pp

Tuttle, M D, and D A. R. Taylor 1994 Bats and mines Bat Conservation International
Resource Publication Number 3 4 1 pp

Twente, J W, Jr. 1955. Some aspects of habitat selection and other behavior of cavern-
dwelling bats Ecology 36:706-732.

Webb, P I , J R Speakman, and P A Racey. 1996. How hot is a hibernaculum9 A review of
the temperatures at which bats hibernate Canadian Journal of Zoology 74:761-765.

02/06 03/08 04/07

New logger S/M213620 TEMP/RH

05/07

06/06 07/06
S/N 213620

Figure 1. Mine temperature of the McDonald Mine East Adit (shallow location), Lake County,
Montana, from December 1998-July 1999. Electronic data recorder was 39.7 m from the
mine portal.

01/08

02/07 03/09 04/08 05/08
New logger S/H/213620 TEMP/RH ...

06/07 07/07
S/N 213620

Figure 2. Relative humidity of the McDonald Mine East Adit (shallow location), Lake County,
Montana, from December 1998-July 1999. Electronic data recorder was 39.7 m from the
mine portal

12/10
1998

01/09

02/08 03/10 04/09

New logger S/NS213613 TEMP/RH

05/09

06/08 07/06
S/N 213613

Figure 3. Mine temperature of the McDonald Mine East Adit (deep location), Lake County,
Montana, from December 1998-July 1999. Electronic data recorder was 106.7 m from
the mine portal.

05/07

Hew logger S/N/213613 TEMP/RH

~1

06/06 07/06
S/N 213613

Figure 4 Relative humidity of the McDonald Mine East Adit (deep location), Lake County,
Montana, from December 1998-July 1999. Electronic data recorder was 106 7 m from
the mine portal

02/08 03/10 04/09

Hew logger S/N/213624 TEMP/RH

05/09

06/08 07/0E
S/N 213624

Figure 5. Mine temperature of the McDonald Mine West Adit, Lake County, Montana, from
December 1998-July 1999. Electronic data recorder was 12.7 m from the mine portal.

10

12/09
1998

02/07 03/09 04/08

Mew logger S/H/213624 TEMP/RH

05/08

06/07 07/07
S/N 213624

Figure 6 Relative humidity of the McDonald Mine West Adit, Lake County, Montana, from
December 1998-July 1999. Electronic data recorder was 12.7 m from the mine portal

u

03/10 04/09 05/09

New logger S/M213604 TEMP/RH ...

06/08

07/06
S/N 213604

Figure 7. Mine temperature of the Gypsum Mine Adit #2, Jefferson County, Montana, from
January- July 1999. Electronic data recorder was 8.0 m from the mine portal.

12

01/08
1999

02/07

03/09 04/08 05/08

New logger S/N/213604 TEMP/RH ...

06/07 07/07

S/N 213604

Figure 8 Relative humidity of the Gypsum Mine Adit #2, Jefferson County, Montana, from
January-July 1999 Electronic data recorder was 8 0 m from the mine portal

13