Bat Research in the West Arm Demonstration Forest
Juliet Craig

Extension Note 013


The consideration of wildlife habitat in the planning of forest harvesting has become an important issue. Insights into the habitat requirements of forest-dwelling animals are essential if biodiversity is to be maintained. Although some mammals have been well-studied, little is known about the ecology of non-game species such as bats.

Bats are the second most diverse mammalian order, having 16 species in British Columbia. They use trees, caves, cliffs and human-made structures as roost sites. All species in B.C. consume only arthropods (mostly insects) and may eat the equivalent of their body weight in insects nightly. Bats survive the winter by hibernating in protected areas or migrating to warmer regions. They are the only mammal capable of true flight and have a well developed echolocation system. This sonar system enables them to detect prey and navigate in complete darkness by listening for the echoes of sounds they emit.

It is expected that at least 10 species of bats inhabit the Interior Cedar-Hemlock (ICH) and Engelmann Spruce-Subalpine Fir (ESSF) biogeoclimatic zones of the Nelson area (Nagorsen and Brigham 1993). These include:

Western small-footed bats (Myotis ciliolabrum) and Western Red bats (Lasiurus blossevillii) may also occur in these areas (Brigham 1993).

Of these bat species, Western Red and Northern long-eared are on the provincial red list (endangered) and Western small-footed and Townsend's big-eared are on the provincial blue list (threatened). Despite this status, there has only been one comprehensive study on bats in the Nelson area (Vonhof and Grindal 1993). Funded by Forestry Canada, it began in 1992 and will continue every summer for four years.

The study sites are located in the West Arm Demonstration Forest (WADF), Kootenay Lake Forest District (Research Summary RS-003, Forest Sciences Section 1992). The study was designed to gather information on distribution, abundance, diversity, roost site selection, diet, and foraging behaviour of bats. The WADF was chosen because bats could be studied in the same areas before and after harvesting. It is the first study to experimentally examine the impact of forest harvesting on bats.

Field research of the long-term study, like most bat studies in Canada, occurs during the summer months only. Information about bats in the fall is also valuable since this is when temperatures drop, insects become less abundant and bats hibernate or migrate. Yet fall data are scarce. This study was designed to supplement summer data by collecting information about species presence, diet, food abundance, and timing of hibernation and migration in the fall.

This 1993 fall study was funded by the Forest Sciences Section of the Ministry of Forests (Nelson Region), Natural Science and Engineering Research Council, and Simon Fraser University. The Universities of Calgary and Regina supplied equipment.


Field research was conducted between September and November, 1993, in the WADF and surrounding area. Presence and activity of bats were determined using QMC mini2bat detectors. These small devices allow high-frequency bat echolocation calls to be heard by an unaided human ear. Bats were also captured in mist nets to be identified, weighed, measured, and subsequently released. Fecal pellets from these bats were collected and dissected to identify the insects consumed, and their contents were compared to insects caught in light/suction traps.


The following results were generated from the fall study. Results from the long-term study are available from Robert Barclay or Mark Brigham.


There is still much to be learned about bats and their habitat requirements. Questions about habitat use, roost trees, foraging sites, diet, and hibernaculum locations remain unanswered. Further information will be essential if bat habitat is to be considered when managing forests for biodiversity. Field work may continue to be extended into the fall months during the remainder of the long-term research project to gain more information. Continued efforts are being made to learn more about these mysterious flying mammals.


Brigham. R. M. 1993. Professor of Biology, Department of Biology, University of Regina, Regina, Saskatchewan, personal communication.

Forest Sciences Section. 1992. The West Arm Demonstration Forest. B.C. Min. For., Nelson, B.C. Research Summary RS-003.

Nagorsen, D. W. and R. M. Brigham. 1993. Bats of British Columbia, UBC Press, Vancouver, B.C.

Vonhof, M.and S. Grindal 1993. Impacts of forest harvesting on the distribution, abundance, and foraging and roosting behavior of bats in the West Arm Demonstration Forest (WADF) near Nelson, B.C. Unpublished progress report for Forestry Canada.

February 1994

For further information, contact:

Robert Barclay Professor of Biology
University of Calgary
Calgary, Alberta
Phone: (403) 220-3564

Mark Brigham Professor of Biology
University of Regina
Regina, Saskatchewan
Phone: (306) 585-4255

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