2013 NORTHEASTERN NATURALIST 20(2):309–324
Bat Species Diversity in the Boreal Forest of Northeastern
Stephen C. Mills1,*, Amanda M. Adams2, and R. Dean Phoenix1
Abstract - In southern Ontario, Canada, the range and distribution of bats is well
known, but their activity in the northeastern part of the province (north of 47°N, east of
85°W) is poorly documented. Using acoustic sampling, we documented the occurrence
of six species of bats in the boreal forest of northeastern Ontario: Eptesicus fuscus
(Big Brown Bat), Lasiurus borealis (Eastern Red Bat), L. cinereus (Hoary Bat), Myotis
lucifugus (Little Brown Bat), M. septentrionalis (Northern Long-eared Bat), and Lasionycteris
noctivagans (Silver-haired Bat). Hoary Bats were recorded more frequently
than all other species. Little Brown Bats were second-most frequently recorded, and the
remaining four species were encountered (mean number passes/hour) significantly less
often. Our records are the most northerly for Big Brown Bats in this part of Ontario.
Although the other species were expected in this area, this is the first study to identify
and confirm the bats present in the boreal forest of northeastern Ontario. This new information
will contribute to efforts to conserve biodiversity in the province and may
inform future studies or monitoring programs associated with the spread of white-nose
syndrome in Ontario.
There are many gaps in knowledge regarding species at the northern limits
of their range, including basic information such as presence, and these gaps
can impact decisions concerning conservation and management. Knowledge
of bats especially is sparse in the north, but this information has become vital
with the discovery of white-nose syndrome (WNS) in Ontario in 2009 (Turner
et al. 2011). White-nose syndrome is an infectious disease caused by a fungal
pathogen that was first discovered in the northeastern United States in 2006;
the disease causes substantial mortality in hibernating bats and ultimately results
in significant population decline, to the point where local extinction of
one of more species may occur (Frick et al. 2010). Regional data related to the
diversity of bat species will help inform conservation efforts because this new
threat has the potential to drastically change regional communities (Timpone
et al. 2011). The importance of species diversity is recognized in Ontario’s
Biodiversity Strategy (Ontario Ministry of Natural Resources 2005), but conserving
biodiversity at the species level is difficult without knowing which
species inhabit a particular region.
1Northeast Science and Information Section, Ontario Ministry of Natural Resources,
5520 Highway 101 East, South Porcupine, ON P0N 1H0, Canada. 2Department of
Biology, Western University, London, ON N6A 5B7, Canada. *Corresponding author -
310 Northeastern Naturalist Vol. 20, No. 2
Eight species of bats are known from Ontario (Dobbyn 1994, van Zyll de
Jong 1985), but little information exists about their distribution in northeastern
Ontario (north of 47°N, east of 85°W). Although extensive range maps
exist for these species, they are often extrapolated from a few confirmed
occurrences (van Zyll de Jong 1985). Historic information exists for Myotis
lucifugus LeConte (Little Brown Bat) near Timmins, ON, the closest city to
our study area (Fig. 1; Fenton 1970), and the Atlas of Mammals of Ontario
(Dobbyn 1994) also reports the presence of the Little Brown Bat and M. septentrionalis
Trouessart (Northern Long-eared Bat) within 100 km of this
location. In addition, Dobbyn (1994) states that Lasionycteris noctivagans
LeConte (Silver-haired Bat), Lasiurus borealis Müller (Eastern Red Bat), and
L. cinereus Palisot de Beauvois (Hoary Bat) can be found throughout Ontario.
We expected these five species to be present in this part of northeastern Ontario.
Furthermore, records for the Eastern Red Bat, Hoary Bat, and Silver-haired
Bat from locations greater than 200 km north of our study area suggest that it
is within the known range of these species (Dobbyn 1994).
The closest records for Eptesicus fuscus Palisot de Beauvois (Big Brown Bat)
are greater than 100 km south of our study site (Dobbyn 1994), but this species
has been documented farther north in northwestern Ontario (van Zyll de Jong
1985), Saskatchewan (Kalcounis et al. 1999), and Alaska (Parker et al. 1997).
These locations are all within the boreal forest region, a vast area dominated by
coniferous forests interspersed with wetlands. The boreal forest is the largest
forest region in Canada and stretches from the Yukon in the west to Newfoundland
in the east (Rowe 1972). This forest region represents the northern extent
of distribution of many species of bats (van Zyll de Jong 1985) and is important
habitat for other wildlife (e.g., landbirds; Blancher 2003).
Published reports for Perimyotis subflavus F. Cuvier (Tricolored Bat) and
Myotis leibii Audobon and Bachman (Eastern Small-footed Bat) indicate that
these species are no closer than 200 km south of our study area. New research,
however, suggests that the Tricolored Bat occurs farther north than previously
documented. Based on data from stable isotopes, Fraser et al. (2012) postulate
that Tricolored Bats spend the summer as far north as the southern tip of James
Bay (Fig. 1)
In the boreal forest of northern Alberta, Patriquin and Barclay (2003) examined
the effects of timber harvesting on bats but documented only three species
(Little Brown Bat, Northern Long-eared Bat, and Silver-haired Bat). They suggested
that other species (e.g., Big Brown Bat and Hoary Bat) not captured or
otherwise detected during their study may have been present. Published range
maps for these additional species (van Zyll de Jong 1985) include the study
area of Patriquin and Barclay (2003), supporting our assertion that the few
documented occurrences for some species of bats may have caused inaccurate
portrayals of their distributions. Extensive work to investigate distribution and
diversity of bats in other northern jurisdictions has been completed (Grindal et
al. 2011, Parker et al. 1997), but studies in Ontario have generally focused on
2013 S.C. Mills, A.M. Adams, and R.D. Phoenix 311
the Little Brown Bat (Dubois and Monson 2007; Fenton 1969,1970) or on areas
south of the boreal forest (Jung et al. 1999).
This study will provide information on both the diversity and relative activity
of bats in our project area and serve as an important baseline against which
we may assess the potential spread and impact of WNS on bat activity. Since
the discovery of WNS in Ontario in 2009, the disease has been documented in
bats in many regions of the province, including locations approximately 100 km
east of our study area during winter 2010 and less than 50 km north of our study area
during winter 2011. These locations represent the most northerly detection of
WNS in Ontario (Turner et al. 2011). The disease is likely to have a dramatic
negative effect on several species of bats in Ontario, including the Little Brown
Bat, Northern Long-eared Bat, and Tricolored Bat (Turner et al. 2011). A recent
emergency assessment by the Committee on the Status of Endangered Wildlife
in Canada (2012) concluded that the Little Brown Bat, Northern Long-eared Bat,
and Tricolored Bat are endangered.
The objectives of our study were to identify the species of bat in clearcut areas
and along edges of patches and intact forest in northern Ontario and examine differences
in relative activity among species, using passive acoustic sampling. We
hypothesized that all species previously documented or predicted to occur in this
area (van Zyll de Jong 1985) would be present. We also predicted that we would
detect the Big Brown Bat and Tricolored bat, because of published evidence suggesting
that they occur farther north than currently indicated (Fraser et al. 2012,
van Zyll de Jong 1985). Based on the mixed composition of the forest and essentially
contiguous forest matrix, we expected that species such as the Little Brown
Bat, a habitat generalist (Fenton and Barclay 1980), and the Northern Long-eared
Bat, a forest specialist (Caceres and Barclay 2000, Henderson and Broders 2008,
Henderson et al. 2008, Hogberg et al. 2002), would both be highly active at edge
sites and less active at clearcut sites. We also predicted that activity of the Hoary
Bat, Eastern Red Bat, and Silver-haired Bat would be highest in clearcut areas
because these species are better suited to forage in open habitats (Lacki et al.
2007, Owen et al. 2004).
Field site description
We conducted our study within a forestry research area of approximately 528
ha (384 ha harvest area and 144 ha residual, unharvested area) south of Timmins,
ON, Canada (N48°28'34",W81°19'42"; Fig. 1) in the boreal forest region of Ontario
(Rowe 1972). The area has flat-to-rolling topography and a mixed-forest
composition. The most abundant species of deciduous trees are Betula papyrifera
Marsh. (Paper Birch) and Populus tremuloides Michx. (Quaking Aspen) (Forestry
Research Partnership 2008); the most common species of conifers are Thuja
occidentalis L. (Eastern White Cedar), Picea mariana (P. Mill.) B.S.P. (Black
Spruce), Picea glauca (Moench) Voss (White Spruce), and Abies balsamea (L.)
312 Northeastern Naturalist Vol. 20, No. 2
P. Mill. (Balsam Fir). Ambient temperatures are highest in July, with an average
daily minimum of 10.5 °C and average daily maximum of 24.2 °C; mean annual
precipitation is 831.3 mm (Environment Canada 2011).
Sampling points were located in 3 site-types: clearcut areas, edges of patches
(patch-edge), and edges of intact forest (forest-edge). Clearcuts were defined as
harvested areas having a residual retention of approximately 25 trees/ha. Patches
were separated from intact forest by at least 30 m and were at least 0.25 ha but not
Figure 1. Map of Ontario, Canada, showing the area where acoustic sampling of bats was
conducted. Light shading indicates the extent of the boreal forest (as described in Rowe
1972). Hatched area represents the distributional range of the Big Brown Bat (from van
Zyll de Jong 1985).
2013 S.C. Mills, A.M. Adams, and R.D. Phoenix 313
greater than 2.0 ha, whereas intact forest was defined as not previously disturbed,
primary forest. No permanent, standing or flowing water was located within the
study area, but water was available in small ephemeral pools and low-lying areas.
We did not quantify the area or number of these features.
We sampled 8 locations within each of the 3 site-types, for a total of 24
sampling sites, from 24 June to 3 August 2009. Each site was surveyed for 1
(n = 17 sites), 2 (n = 5), 3 (n = 1), or 4 (n = 1) nights. From 18 June to 28 July
2010, we surveyed 8 patch-edge sites and 8 forest-edge sites, but only one of
the clearcut sites, for a total of 17 sampling sites; each site-type was surveyed
for 2 (n = 10 sites), 3 (n = 6), or 4 (n = 1) nights. At each site, echolocation
calls were recorded using a full-spectrum ultrasonic detector (batcorder 2.0,
ecoObs, Nuremberg, Germany). On all sampling nights, we deployed two
detectors, each at a different location. Detectors were attached to trees that
were approximately 15–20 cm in diameter at 1.2 m above the ground; the
microphone was oriented parallel to the ground or angled slightly downward,
to prevent water from falling on the microphone. We cleared surrounding
vegetation for 1–2 m around the microphone to minimize interference.
Detectors were programmed to record whenever an echolocation call was
detected within the fixed recording period of 2200 hours (2009: 29–61 min
after sunset; 2010: 30–52 min after sunset) to 0400 hours (2009: 84–123
min before sunrise; 2010: 83–115 min before sunrise).
We used weather data from Timmins, ON, the closest weather station (37 km)
to our study area (Environment Canada 2011). We recognize that meteorological
factors can affect activity levels of bats (Erickson and West 2002) and eliminated
sampling nights from our analyses during which mean nightly temperature was
less than 10 °C, total duration of precipitation (rain, rain showers, or drizzle) was >4 h,
or if precipitation occurred for the entire first 2 h of our sam pling period.
We identified acoustic recordings to species using quadratic discriminant
function analysis (DFA). The DFA compared our unidentified data to a training
dataset and classified each call based on 11 call parameters that were extracted
by the automated detection feature of callViewer18 (Skowronski and Fenton
2008). CallViewer is a custom echolocation sound-analysis program written
with MATLAB (The MathWorks, Nadick, MA). The 11 call parameters were
minimum frequency (Fmin), maximum frequency (Fmax), duration, frequency
of most energry (FME), 10th percentile of energy (F10), 60th percentile
of energy (F60), 90th percentile of energy (F90), median frequency slope
(dFmedian), median energy slope (dEmedian), median frequency smoothness
(sFmedian), and median energy smoothness (sEmedian).
The training dataset consisted of known echolocation calls for seven species
of bats present in Ontario; it did not include the Eastern Small-footed Bat because
314 Northeastern Naturalist Vol. 20, No. 2
we cannot distinguish its echolocation calls from those of the Little Brown Bat
(Table 1). The training dataset was compiled by biologists at Western University
from various locations over numerous years. All reference recordings came from
free-flying bats, with search-phase echolocation calls outside of known roosts or
at foraging sites where species and individual bats were identified unambiguously.
No reference recordings came from hand-released individuals.
We always analyzed the harmonic with most energy within each call, which
was the fundamental harmonic for all species. We used only one call from each
individual bat to eliminate pseudoreplication in the training dataset. Our data
were filtered to eliminate noise and weak or fragmented calls, because the DFA is
not capable of assigning “unknown” classifications. Cross-validation was run to
determine the classification accuracy of the training dataset (Table 1). All species
were weighted equally in the DFA. We used R, version 2.13.1 (R Development
Core Team 2011) for all acoustic analyses. Additionally, 41% of the files that
contained bat calls were visually validated as additional confirmation of the accuracy
of the DFA, and calls that could not be visually identified to species were
classified as “unknown”.
To account for differences in the number of sampling nights among sites,
we calculated bat activity as mean number of acoustic files per hour (hereafter
referred to as passes/hour). Each acoustic file was counted as a pass because
of the nature of the trigger algorithm on batcorders, with most (98%) acoustic
files containing only a call sequence (>2 calls) from a single individual
of one species. We determined mean number of passes/hour for each species
by site-type combination, which we then transformed using log(passes/hour
+ 1)0.25. Because data were still non-normal, we used the Kruskal-Wallis test
in R, version 2.13.1 (kruskal.test; R Development Core Team 2011) to look
for significant differences in transformed passes/hour among species, among
site-type, and among species within each site-type and conducted post-hoc
tests with kruskalmc in the pgirmess package, version 1.5.2 (Giraudoux 2011).
Multiple pairwise comparisons using kruskalmc determine which groups are
significantly different (P < 0.05). Pairwise differences are significant when
Table 1. Classification accuracy (%), representing the proportion of known calls in the training
dataset correctly identified to species with quadratic discriminant function analysis, using crossvalidation.
Species known from OntarioA Number of reference calls Classification accuracy (%)
Big Brown Bat 50 78
Eastern Red Bat 58 88
Hoary Bat 52 90
Little Brown Bat 50 90
Northern Long-eared Bat 33 82
Silver-haired Bat 50 94
Tricolored Bat 42 93
AClassification did not include the Eastern Small-footed Bat, due to difficulty in distinguishing it
acoustically from the Little Brown Bat.
2013 S.C. Mills, A.M. Adams, and R.D. Phoenix 315
pairs have an observed value that is statistically different from a critical value.
We also calculated the proportions of total sites and 95% confidence intervals
where each species was encountered, as a relative measure of occurrence for
the study area. These statistical analyses were conducted with SYSTAT version
13 (Systat Software, Inc., Chicago, IL).
We recorded 3607 files (passes), and 1490 were visually validated. We were
unable to identify 31 (2%) of the visually validated files with bat calls to species
and excluded them from further analyses. The remaining 3576 passes with
bat activity (2009: 2273 passes, 2010: 1303 passes), included 24,131 individual
echolocation calls (2009: 15,907 calls, 2010: 8224 calls) that we were able to
identify to species (Table 2).
We confirmed the presence of 6 species of bats: Big Brown Bats, Eastern
Red Bats, Hoary Bats, Little Brown Bats, Northern Long-eared Bats, and Silver-
haired Bats. Little Brown Bats occurred at the highest proportion of sites
(21 sites, 87.5%), and Big Brown Bats at the lowest (12 sites, 50.0%), whereas
all other species occurred at an intermediate proportions of sites (Table 2). We
speculated that since Eastern Small-footed Bats were uncommon in Ontario
(Dobbyn 1994, van Zyll de Jong 1985), especially at the northern extent of
their range, and that misidentification of these bats as Little Brown Bats occurred
rarely, if at all, and would not affect our estimates of relative activity
levels for Little Brown Bats.
Bat activity was not equal among site-types or species. Overall, bats were significantly
more active (mean number passes/hour ± SE) at patch edge sites (2.10
± 0.68) than at clearcut sites (0.21 ± 0.07) (H2 = 12.08, P = 0.0024; Fig. 2A).
Hoary Bats (3.75 ± 1.22) and Little Brown Bats (1.37 ± 0.54) had significantly
higher activity levels than all other species (H5 = 107.01, P < 0.001; Fig. 2B).
Hoary Bats were significantly more active at clearcut sites than all species except
Little Brown Bats, whereas Little Brown Bats had significantly higher activity
levels than Silver-haired Bats at the same sites (H5 = 40.25, P < 0.001; Fig. 3).
Within the forest-edge site-type, activity levels of Little Brown Bats, Hoary Bats,
and Northern Long-eared Bats were not significantly different from each other,
Table 2. Summary of passes and number of calls, by species of bat, for 2009 and 2010, and the
proportion (95% C.I.) of sampling sites at which each species was detected.
Species Passes Calls Passes Calls Proportion Sites (95% C.I.)
Big Brown Bat 52 312 18 94 0.500 (0.204)
Eastern Red Bat 19 135 76 939 0.667 (0.193)
Hoary Bat 1867 11,701 782 2473 0.833 (0.152)
Little Brown Bat 254 3097 372 4312 0.875 (0.135)
Northern Long-eared Bat 38 373 29 307 0.667 (0.193)
Silver-haired Bat 43 289 26 99 0.583 (0.201)
316 Northeastern Naturalist Vol. 20, No. 2
Figure 2. Comparison of bat activity among site-types (all species; A) and among species (all
site-types; B) in the boreal forest of northeastern Ontario, Canada. Activity is represented by
mean number of passes/hour (± SE). Different lowercase letters above bars denote significant
differences, as determined by nonparametric multiple comparisons (P < 0.05).
2013 S.C. Mills, A.M. Adams, and R.D. Phoenix 317
but were significantly higher than the other 3 species (H5 = 46.88, P < 0.001;
Fig. 3). At patch-edge sites, Hoary Bats had significantly higher activity levels
than Eastern Red Bats, Northern Long-eared Bats, and Silver-haired Bats (H5 =
32.36, P < 0.001; Fig. 3).
Using acoustic sampling, we demonstrated the occurrence of six species of
bats in a study area presumably representative of the boreal forest of northeastern
Ontario, a region where few records previously existed. Our findings support our
hypothesis that all previously documented species were present, and we added to
the region’s list of species by detecting the Big Brown Bat; however, Tricolored
Bats were not detected in our study. Our acoustic sampling has helped fill a gap
in existing data sets, similar to surveys in other regions (e.g., Virginia; Timpone
et al. 2011), and has increased our knowledge of bat communities in the boreal
forest of Ontario.
Bat activity is commonly highest at edge habitats (e.g., Grindal and
Brigham 1998, Morris et al. 2010), for reasons such as increased insect activity
(Grindal and Brigham 1998, Morris et al. 2010) and corridor-like features
for commuting (Owen et al. 2004). This pattern is consistent with our findings
that patch edges had the highest levels of activity, most likely because of the
benefit of edges to bats. Additionally, patches have greater edge-to-area ratios
Figure 3. Activity, by site type (clearcut, forest edge, patch edge), of 6 species of bats
in the boreal forest of northeastern Ontario, Canada. Activity is represented by mean
number of passes/hour (± SE) for each species. Different lowercase letters denote species
that were significantly different from each other within each site-type, as determined by
nonparametric multiple comparisons (P < 0.05).
318 Northeastern Naturalist Vol. 20, No. 2
due to their relatively small size (0.25–2.0 ha) than comparable intact forest
and more edge available to foraging bats. Although we focused on sampling at
edges and not in the more cluttered environment within forests, we believe this
approach had little impact on our detection of the highly maneuverable forest
specialist, the Northern Long-eared Bat (Hogberg 2002, Kalcounis et al. 1999,
Patriquin and Barclay 2003, Owen et al. 2004). Jantzen (2012) found that
Northern Long-eared Bats had highest activity along edges compared to forest
interiors and fields, while Sleep and Brigham (2003) reported that clutter-tolerant
species still avoid cluttered areas.
We predicted that Hoary Bats would be present, based on historical records,
but did not expect them to be the most active species along patch edges. Hoary
Bats are considered open-area specialists, because of their morphology and echolocation
call characteristics (Owen et al. 2004, Veilleux et al. 2009), but were
most likely attracted to the patch-edge habitat because of the intermediate level
of disturbance. This intermediate level of disturbance may provide increased
foraging opportunities associated with structural diversity created by irregular
patch boundaries and windthrow, where trees are more susceptible to blowing
down along edges. Hoary Bats also have a close association with forest habitat
because they roost solitarily in foliage (Cryan and Veilleux 2007, Klug et al.
2012). Although acoustic recordings indicated that Hoary Bats were the most
active species in all site-types, we consider that a difference in echolocation call
characteristics and foraging strategies may explain the disagreement with our
prediction that this species would be most active in clearcut areas. Hoary Bats
can be more detectable because they have narrowband, low-frequency echolocation
calls that travel farther and are less affected by atmospheric attenuation than
the calls of the other species in the area.
Like Hoary Bats, Eastern Red Bats and Silver-haired Bats are long-distance
migratory species known to occur in close association with forests and roost
almost exclusively in trees (Brigham 2007). Their range is fairly extensive in
Ontario, as well as most of Canada from British Columbia to Nova Scotia (Kunz
1982, Shump and Shump 1982, van Zyll de Jong 1985). Eastern Red Bats roost
alone in hardwood trees and prefer trees located in low-density stands (Carter
and Menzel 2007, Hutchinson and Lacki 2000), which might also explain their
higher activity along patch edges. Silver-haired Bats roost alone or in small
groups in crevices of tree trunks, behind loose bark or the folds of heavily furrowed
bark (Barclay et al. 1988, Mattson et al. 1996, Vonhof and Barclay 1996).
Selectively harvested Pinus strobus L. (Eastern White Pine) stands did not exist
in our study area, but are important habitat for Eastern Red Bats (Jung et al. 1999)
and Silver-haired Bats elsewhere in Ontario, as both species roost preferentially
in large trees (Crampton and Barclay 1998, Jung et al. 1999). These two species
had relatively low activity at our site, potentially because of a lack of suitable
roosting habitat. Other possibilities exist to explain the low relative activity of
Eastern Red Bats, such as potential long-term population decline (see Winhold
et al. 2008) or spatial partitioning with Hoary Bats (Kunz 1973).
2013 S.C. Mills, A.M. Adams, and R.D. Phoenix 319
Little Brown Bats occurred at 87.5% of sites during our study, which agrees
with the extensive range and ubiquitous nature of this species throughout the
rest of the province. Although they did not occur at significantly more sites
than most other species, Little Brown Bats were more active than all other
species, except Hoary Bats. We did not detect a difference in Little Brown
Bat activity among site-types, likely because of their preference to forage
(Patriquin and Barclay 2003) and commute (Hogberg et al. 2002) along edges.
Their higher-than-expected level of activity in clearcut areas may be due to
their avoidance of clutter (Sleep and Brigham 2003), although Kalcounis and
Brigham (1995) found some intraspecific variation in Little Brown Bats, so
that individuals with lower wing loading were able to forage in more cluttered
environments. The Little Brown Bat typically forages above water (Jung et al.
1999) and in riparian habitats more than in upland habitats (Owen et al. 2004),
although they will forage over ephemeral pools (Francl 2008). These bats may
be more common in other parts of the boreal forest where standing or flowing
water is more abundant.
Activity levels of Northern Long-eared Bats were statistically equal in
both types of edge sites, as predicted, but activity at edges was not significantly
higher than at clearcut sites. We speculate that the relatively low level
of activity for this species overall made it difficult to detect any difference in
activity among site-types. Northern Long-eared Bats are common at latitudes
above 50°N (Caceres and Barclay 2000) and are considered forest specialists,
typically foraging in cluttered habitats and roosting in tree cavities or behind
exfoliating bark (Henderson and Broders 2008, Henderson et al. 2008, Hogberg
et al. 2002, Jung et al. 1999). Although the species can be common, it still
had a lower activity level than the Hoary Bat and Little Brown Bat. Northern
Long-eared Bats, though, have low-intensity, high-frequency calls that are
difficult to detect (Grindal et al. 2011, Jung et al. 1999), and these bats are often
under-represented in acoustic surveys. Furthermore, Grindal et al. (2011)
found that Northern Long-eared Bats were more commonly captured in mistnets
than detected with acoustic sampling, supporting this assertion and also
confirming that different sampling techniques (e.g., capture versus acoustic)
will often result in different estimates of occurrence.
With no previous records of Big Brown Bats in this part of northeastern Ontario,
we are now able to confirm their presence beyond the current distributional
range of this species (Fig. 1). Big Brown Bats occurred at fewer sampling sites
and at significantly lower levels of activity than Hoary Bats or Little Brown Bats.
Although we predicted Big Brown Bats would be present in our study area, we
also presume that our study site is at, or near, the northern extent of their range
in northeastern Ontario. We expect the relative activity of this species to be low
in the boreal forest, which may account for the low activity levels detected in
our study. Kurta et al. (1989) found that this species decreased greatly in abundance
between the Deciduous and Coniferous Forest Biomes, and other studies
have failed to detect Big Brown Bats at the northern extent of the known range
320 Northeastern Naturalist Vol. 20, No. 2
in Ontario and Alberta (Jung et al. 1999, Patriquin and Barclay 2003). We assert
that low abundance may have been a factor affecting the detection of this species.
Relative activity of Big Brown Bats was equal among site types, consistent with
their lack of preference for a particular type of foraging habitat (Kurta and Baker
1990). Big Brown Bats roost in buildings, rock crevices, and tree cavities (Agosta
2002, Kurta and Baker 1990) and have shown a preference for roosting sites in
Quaking Aspen in southern Saskatchewan (Kalcounis and Brigham 1998). All
cavities that were searched in that study showed evidence of use by bats, and
Kalcounis and Brigham (1998) hypothesize that roost sites may be limiting for
Big Brown Bats. Quaking Aspens are present in our study area but are not the
most abundant tree species (Forestry Research Partnership 2008). Big Brown
Bats normally roost within 2 km of foraging areas (Kurta and Baker 1990), and
a limited number of roost sites within commuting distance of our study area may
explain the low relative activity of Big Brown Bats.
We were unable to confirm the presence of Tricolored Bats, even though recent
evidence suggests they occur at more northern latitudes (Fraser et al. 2012).
Although our site might be beyond the range of this species, there is a chance
that we would not have detected Tricolored Bats in the area because they have
a preference for foraging over water (Broders et al. 2001). Similarly, we may
not have detected these bats near roost sites due to a lack of suitable roost trees.
Although Tricolored Bats roost in many species of deciduous trees (Carter and
Menzel 2007), Veilleux et al. (2003) found that roosts were located in oak trees
more frequently than would be expected based on the occurrence of oaks in their
study area. Also, there is no evidence that these bats roost in Paper Birch or Quaking
Aspen (Carter and Menzel 2007), the most common deciduous trees in our
Confirming species richness of bats in northeastern Ontario is an important
contribution to the efforts to conserve biodiversity in the province. With greater
knowledge of which species are present in a given area, managers are better able
to consider things like habitat requirements relative to proposed developments or
resource-extraction activities and potential impacts of those activities and developments
on habitat use or activity levels of these species. Additionally, this report
and other studies (e.g., Timpone et al. 2011) provide important baseline data to
inform future surveys or analyses intending to examine the impact of WNS on bat
activity. Although the relatively high activity levels of Little Brown Bats in our
study indicate that there still are healthy colonies in Ontario, presumably unaffected
by WNS, our data provide a valuable comparison for future studies and the
increased monitoring efforts for this species as WNS continues to spread.
The Ontario Ministry of Natural Resources’ Science and Information Branch provided
funding for this project. This project was conducted at a collaborative research site
established by partners from Natural Resources Canada: Canadian Forest Service, the
Forestry Research Partnership, and the Ontario Ministry of Natural Resources. We thank
2013 S.C. Mills, A.M. Adams, and R.D. Phoenix 321
L. Venier for helping determine sampling locations, D. Etheridge for logistical support,
and A. Chodenski, K. Cowcill, J. Dane, L. Eckert, T. Fleury, C. McLister, D. Potvin, and
N. Romanow for field and analytical support. We would also like to thank L. Hooton for
significantly contributing to the development of the DFA with A.M. Adams. Statistical
advice was contributed by L. Landriault, and E. Fraser provided helpful comments on an
earlier draft of this manuscript. This manuscript has benefited from thoughtful comments
by 2 anonymous reviewers.
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