RESEARCH EXTENSION NOTE
NO. 9 – July 2014

BURNING FOR NORTHERN MOUNTAIN UNGULATES:
EFFECTS OF PRESCRIBED FIRE

By
Krista L. Sittler, Katherine L. Parker, Michael P.
Gillingham, Roger D. Wheate & Douglas C. Heard

Krista Sittler completed a MSc. in the Natural Resources and Environmental
Studies Graduate Program, University of Northern British Columbia, Prince
George, B.C., Canada. Katherine Parker and Michael Gillingham are faculty
members in the Ecosystem Science and Management Program and members of the
Natural Resources and Environmental Studies Institute, University of Northern
British Columbia, Prince George, B.C., Canada. Roger Wheate is a faculty member
in the Geography Program and a member of the Natural Resources and
Environmental Studies Institute, University of Northern British Columbia, Prince
George, B.C., Canada. Douglas Heard is with BC Fish, Wildlife and Habitat
Division, BC Ministry of Forests, Lands and Natural Resource Operations, Prince
George, B.C., Canada.

Sittler, K.L., Parker, K.L., Gillingham, M.P., Wheate, R.D. & Heard, D.C. 2014. Burning
for northern mountain ungulates: effects of prescribed fire. Natural Resources and
Environmental Studies Institute. Research Extension Note No. 9, University of Northern
British Columbia, Prince George, B.C., Canada.
This paper can be downloaded without charge from:
http://www.unbc.ca/nres-institute/research-extension-note-series

Sittler, Parker, Gillingham, Wheate & Heard  Effects of Prescribed Fire on Ungulates

ii

The Natural Resources & Environmental Studies Institute (NRESi) is a formal
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iii

NRESi Research Extension Note No. 9
July 2014

CONTENTS
Abstract ........................................................................................................................................... 2
Introduction. .................................................................................................................................... 3
Methods........................................................................................................................................... 4
Study area ................................................................................................................................... 4
Vegetation response to prescribed fire ........................................................................................ 5
Ungulate response to prescribed fire .......................................................................................... 5
Data analyses .............................................................................................................................. 6
Results & Discussion ...................................................................................................................... 6
Conclusions & Recommendations ................................................................................................ 12
Winter range and season for prescribed burning ...................................................................... 12
Frequency of burning – based on forage quality and quantity ................................................. 12
Size and aspect of prescribed burns .......................................................................................... 13
Dynamics of the large-mammal assemblage ............................................................................ 13
References ..................................................................................................................................... 15
Acknowledgments......................................................................................................................... 18

Sittler, Parker, Gillingham, Wheate & Heard  Effects of Prescribed Fire on Ungulates

1

Abstract
Prescribed fire is used as a management tool to
enhance ungulate habitats. In northeastern
British Columbia, up to 7,800 ha are burned
annually. Yet relatively few studies have
quantified the role of fire on plant and animal
response, and whether it enables competition
between focal grazing species such as Stone's
sheep (Ovis dalli stonei) and elk (Cervus
elaphus).
In
the
Muskwa-Kechika
Management Area, we examined the response
of Stone's sheep and elk to seasonal changes in
forage quantity and quality over an elevation
gradient in areas recently burned by prescribed
fires versus unburned control areas. We
monitored vegetation and fecal-pellet transects
at a fine scale and used Landsat imagery,
survey flights, and telemetry locations at a

2

landscape scale. One year after burning,
forage digestibility and rates of forage growth
were higher on burned than unburned areas.
At both scales, Stone's sheep and elk always
used burns more than unburned areas in
winter. Stone's sheep and elk appeared to
partition their use of the landscape through
topography and land cover. Increased use of
burned areas suggests that prescribed fires
enhanced habitat value for grazing ungulates at
least in the short-term. By altering animal
distributions, however, use of prescribed fire
has the potential to change predator-prey
interactions.

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Introduction.
Fire has been the dominant single naturaldisturbance agent influencing the northern
British Columbia (BC) landscape since the
last ice age (Backmeyer et al. 1992).
Successional stage of plant communities is
typically reset after fire.
Over time,
overlapping fires and their recovery create a
mosaic of small younger patches embedded
within a matrix of older patches (Turner et al.
1997, Johnson et al. 1998), thereby shaping
the heterogeneity of the landscape. The
increases in forage quality and quantity in
burned areas exert a “magnet effect”
(Archibald et al. 2005) for grazing ungulates.
Prescribed fires, therefore, are used as a
habitat enhancement tool by management
agencies to benefit ungulates. In northeastern
BC, the Peace-Liard Prescribed Burn Program
of the provincial government has been using
prescribed burning for over 30 years. Initially
the prescribed burns targeted areas to enhance
range value for elk (Cervus elaphus), but the
program has expanded to benefit Stone's sheep
(Ovis dalli stonei), moose (Alces alces) and
mountain goats (Oreamnos americanus). Up
to 7,800 ha are intentionally burned each year
in the Peace Region in an effort to enhance
wildlife habitat, and have led to a landscape
with 41% of all burned area (including from
wild fires) resulting from prescribed fire
(Lousier et al. 2009). The Peace Region is
known for its abundance and diversity of
ungulates and their predators.

A recent review and synthesis of past fire
history in this part of the province identified
knowledge gaps and provided a framework for
a research monitoring plan (Lousier et al.
2009).
Long-term outcomes of the
wildlife/prescribed fire research program were
to maintain ecological diversity, and the
presence and number of species of large
ungulates.
To properly evaluate the
effectiveness in achieving these long-term
outcomes, Lousier et al. (2009) identified the
need to better understand how prescribed
burns affect: 1) the density and distribution of
target species; 2) the composition and
dynamics of burned vegetation communities;
3) the potential for competition for forage and
space between sympatric species; and 4)
predator-prey dynamics. We approached the
first three research needs by documenting
resource use by two focal grazers – Stone's
sheep and elk – in response to prescribed
burning and by monitoring the indirect effects
of fire on these species though direct effects
on the vegetation. Due to their generalist diet
and ease of dispersal, elk in northern BC are
expanding (Shackleton 2013), potentially into
the small traditional ranges of Stone's sheep.
There is concern that the management
activities of prescribed burning may promote
competition between elk and Stone’s sheep,
with human-initiated fires changing ecosystem
dynamics.

Sittler, Parker, Gillingham, Wheate & Heard  Effects of Prescribed Fire on Ungulates

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Figure 1. The Besa-Prophet area (inset) surrounding and including the Besa-Prophet Pretenure Planning Area in northeastern British Columbia. Locations of seven new prescribed
burns implemented for this study are shown by black (2010) and yellow (2011) polygons.
Changes in vegetation quantity and quality resulting from fire were monitored in the four 2010
burns. Locations of older prescribed burns (1980 – 2010) in the Besa-Prophet area are
shown in red.

Methods
Study area
The Besa-Prophet area (approximately
741,000 ha between 57°11' and 57°15'N;
121°51' and 124°31'W) within the MuskwaKechika Management Area of northeastern
BC supports one of the most diverse large
mammal predator-prey systems in North
America. It surrounds and includes the BesaProphet Pre-Tenure Planning Area (a zone
that requires specific management planning
prior to oil and gas exploration and
development) and Redfern Keily Provincial

4

Park (Figure 1). Elevations range from ~700–
2200 m (tree line between 1450–1600 m; Lay
2005) and encompass three biogeoclimatic
zones (Meidinger and Pojar 1991). A unique
topography of numerous east-west drainages
and south-facing slopes provides excellent
wintering habitat for large ungulates: Stone's
sheep, elk, moose, caribou (Rangifer tarandus
caribou), some mountain goats, deer
(Odocoileus spp.), and bison (Bison bison).
The large predators are wolves (Canis lupis),
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grizzly bears (Ursus arctos), black bears
(Ursus americanus), wolverines (Gulo gulo),
coyotes (Canis latrans), and a few cougars
(Puma concolor). Human activities include
some snowmobiling and use of all-terrain
vehicles, hunting, fishing, hiking, horseback
riding, and prescribed burning. The latter
contributes to the heterogeneity of the
landscape that supports this globally renowned
large-mammal assemblage. Since 1980, there
have been 138 sites intentionally burned, often
repeatedly, in the Besa-Prophet area (Sittler
2013).
Vegetation response to prescribed fire
Seven prescribed fires were implemented at
sites associated with four drainages in the
Besa-Prophet area between 15 May and 01
June 2010 and 2011 as part of the Peace-Liard
Prescribed Burn Program. The resultant burns
ranged in size from 150 to 1000 ha on southfacing (Richards, Townsley) and west-facing
(Nevis, Luckhurst) sites. At four of the
burned areas (referred to as ‘burns’)
implemented in 2010 and at adjacent
unburned control areas (referred to as
‘unburned areas’), we took measurements
prior to burning, the year of burning, and 1
year after burning in winter (late May) and
summer (mid-July). On 50-m vegetation
transects at high, mid, and low elevations, we
measured vegetation cover and height, species
diversity, and forage biomass. Mid elevations
for each burn and its control were 1300, 1650,
1483, 1530 m for Richards, Townsley, Nevis,
and Luckhurst sites, respectively.
Midelevation transects were 100 m higher than
low transects and 100 m lower than high
transects. We determined nutritional quality
of forage (graminoids and forbs) samples

using laboratory analyses of digestibility and
protein content. Over the course of this study,
we repeated vegetation sampling five times on
24 transects (four sites, each with three
transects – high, mid, low elevations – on
burns and unburned areas) for a total of 120
transects. We quantified forage quantity and
quality after clipping and analyzing samples
from 360 plots (three per transect). To
document large-scale vegetation response to
fire, we compared satellite images (Landsat 5
TM, Landsat 7 +ETM) from the year of the
burn and 2 years after the burn.
We
monitored changes in vegetation biomass (net
primary productivity) with the normalized
difference vegetation index (NDVI; Hope et
al. 2007).
Ungulate response to prescribed fire
As a fine-scale measure of animal use of
burned versus unburned areas, we recorded
the species of each ungulate fecal pellet group
on 100-m transects at the same elevations as
the vegetation sampling in winter and
summer. We also collected and analyzed data
over 2 years from 11 female Stone's sheep and
22 female elk (11 in each year) fitted with
global positioning satellite (GPS) collars that
were programmed to acquire animal locations
at 6-hour intervals. To supplement data from
individuals,
we
conducted
monthly
distribution flights by fixed-wing aircraft over
a 1-year monitoring period. We recorded the
distribution of groups of elk and Stone's sheep
in relation to prescribed burns at high, mid,
and low elevations along a 2-hour route over
an area that encompassed all GPS-collared
animals as well as 28 burns of varying size
and age (newly implemented burns and older
burns).

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Data analyses
We used transects as the sampling unit for all
our analyses of vegetation and pellet counts.
Data collected in three plots along each
transect within a sampling period were
averaged before analysis. To assess the
influence of prescribed burning on vegetation
quantity (forage biomass, forage cover, shrub
cover), forage quality (crude protein,
digestibility), plant species diversity and
richness, and ungulate pellet counts, we used
mixed-model regressions that tested the
effects of treatment (burned versus unburned),
elevation (high, mid, low) and site (Richards,
Townsley, Nevis, Luckhurst).
Because
vegetation structure and composition differed
seasonally, we tested post-burn effects in
summer and winter separately.
We developed resource selection models to
quantify characteristics that best described
habitat selection (Burnham and Anderson
2002) by the GPS-collared Stone’s sheep and
elk, specifically to better understand the
influence of prescribed burns. For all GPS
locations, we used a Geographical Information
System (GIS) to query the elevation, slope,
aspect, terrain ruggedness, and land cover.
Land cover was described by 11 classes (Lay
2005, Sittler 2013), which included three burn
classes. The ‘Burn shrub’ class was typically
older burns containing deciduous shrubs (<2
m), ‘Burn grass’ referred to recent burns with
open grass meadows most often found on
south-facing slopes, and ‘New burns’ were the
seven new (2010 and 2011) burns aged 1 and
2 years. We developed models for each
collared individual, and then averaged those
models within species in spring, summer, fall,
early winter and late winter.

6

We also quantified relative importance of the
land-cover classes, with emphasis on the burn
classes. Importance was calculated as relative
use (based on GPS locations) multiplied by
availability (five randomly sampled points per
GPS fix), scaled to 1.0 (Stewart et al. 2010).
This calculation helps identify land-cover
classes that are important to Stone's sheep and
elk, but which might not be identified as
selected in the selection models because of
their abundance on the landscape (Stewart et
al. 2002). We used descriptive statistics to
examine the differential use of topography
(elevation, slope, ruggedness) and distance to
a burn.

Results & Discussion
The effects of prescribed fire on forage
quantity and quality varied with site, season,
and elevation (Table 1). We were unable to
detect a difference in the total amount of
forage biomass on the vegetation transects 1
year after burning compared to unburned
areas. The rate of forage growth, however,
was higher on burns than unburned areas,
suggesting that the expected increase in
biomass following burning may not have
peaked. By the second summer following
burning, satellite imagery (NDVI) confirmed
that plant biomass on burns was higher. There
was always more forage on south-facing sites
(Richards, Townsley) than west-facing sites
(Nevis, Luckhurst).
In terms of forage
quality, digestibility increased following
burning in both summer and winter, and was
highest 1 year after burning. Crude protein
was higher in the new growth on burns in late
winter after the fire, but returned to pre-burn
levels by 1 year after burning.
The
availability of high-quality forage for
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Table 1. Summary of vegetation response to prescribed burns implemented in the Besa-Prophet
area of northern British Columbia in spring 2010, with follow-up monitoring in the year of the burn and
1 year after burning in summer and late winter. Vegetation response varied by site and elevation.
Vegetation characteristic

Response to prescribed burning

Forage quantity
Biomass

Scale-dependent. Differences between burns and unburned areas
were not detected at the scale of the 50-m transect by 1 year after
burning. Based on NDVI values, forage biomass was still increasing 2
years after burning in summer. The rate of forage growth was higher
on burns than unburned areas. Forage biomass was always higher
on south-aspect sites than west-aspect sites.

Green-up

Forage green-up was earlier on burned sites than unburned sites and
was less hindered by litter.

Forage cover

Shrub cover was reduced following burning at every site, opening up
areas for herbaceous cover to increase.

Diversity

Plant diversity declined in the year of the burn, but rebounded almost
to unburned levels by 1 year after burning.

Forage quality
Crude protein

Crude protein increased in the new growth on burns, but declined to
pre-burn levels by 1 year after burning.

Digestibility

Forage digestibility increased on burns, was highest 1 year after
burning, and was higher on burns than unburned areas.

Available forage
(quantity × quality)

Available digestible protein and digestible dry matter per unit area
were higher on south-aspect sites than west-aspect sites. Because of
variation among sites and across elevation gradients, there was no
statistical difference between burns and unburned areas the year of
burning and 1 year after burning.

ungulates (quantity × quality) was higher on
south-aspect sites than west-facing sites.

detrimental effects on forage quality in winter
for ungulates (Kohl et al. 2012).

With the reduction in shrubs following
prescribed fire, herbaceous cover increased
(Table 1). Fire reduced species diversity in
the year of the burn, but by 1 year after
burning, species diversity increased to almost
that of unburned areas.
There was no
introduction of invasive species (Sittler 2013),
which can out-compete native plants and have

Stone's sheep and elk were the two species
that used burned slopes most, based on pellet
counts and animal distribution flights. Table 2
provides a summary of both species' response
to burning at a fine scale (fecal pellets) and at
the landscape scale (GPS-collared individuals
and distribution flights to record group
locations). Burns had more use by these two
species than unburned areas at both scales.

Sittler, Parker, Gillingham, Wheate & Heard  Effects of Prescribed Fire on Ungulates

7

Table 2. Summary of Stone's sheep and elk response to prescribed burns in the Besa-Prophet area
of northern British Columbia.
Animal use metric

Response to prescribed burning

Stone's sheep
Pellet counts

More use was observed in winter than summer. Highest use was at
high elevations on Luckhurst, which had high burn severity.

GPS collar locations

Individuals selected for prescribed burns in fall, winter and late
winter. Burns were most important in winter and late winter. The
proportional use of burns, averaged across individuals, was highest
in late winter when 46% of Stone’s sheep locations were on burns
(New burns = 27. 6 ± 7%, Burn grass= 7.3 ± 2%, Burn shrub = 10.7 ±
2%).

Distribution flight data

More Stone’s sheep were always observed on burns than on
unburned areas. Larger groups were observed in winter than
summer.

Elk
Pellet counts

Highest use was on south-aspect sites (Richards and Townsley),
where there was more vegetation biomass.

GPS collar locations

Individuals selected for prescribed burns in every season. Burns
were important in all seasons. The proportional use of burns,
averaged across individuals, was highest in late winter when 80% of
elk locations were on prescribed burns (New burns = 23.9 ± 6%,
Burn grass = 21.5 ± 3%, Burn shrub = 34.6 ± 3%).

Distribution flight data

More elk were always observed on burns than unburned areas.
Larger groups were observed in winter than summer.

Stone’s sheep used higher elevations most,
whereas elk use was distributed across
elevations. For Stone’s sheep, use of burns
was highest at the end of the first winter (late
May) after burning and in the following
summer. Among sites, use was highest postburn on Luckhurst, which had the highest burn
severity and consequently the lowest shrub
and forage cover as well as the lowest
availability of digestible forage. This site,
however, had the highest crude protein values
because new forage emerged sooner at the end
of winter. Stone's sheep are able to selectively

8

forage on the most nutritious parts of plants
even in low-biomass areas (Seip et al 1985a,
1985b), unlike elk that require much larger
amounts of forage. Highest use of burns by
elk was on the south-facing sites (Richards,
Townsley) with the highest forage biomass.
Throughout the year, both species always
selected for south aspects and usually selected
to be close to a burn. Stone's sheep selected to
be on the New burn, Burn grass, or Burn shrub
classes in fall, winter and late winter. Elk
selected to be on burns in every season, with
highest selection for the Burn shrub class
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Figure 2. Selection coefficients (βi ± SE) for the three burned land-cover classes (New burn, Burn
grass, Burn shrub) from the best global resource selection models by season for GPS-collared
female Stone's sheep (A) and elk (B) in the Besa-Prophet area of northern British Columbia.
Positive βi indicates selection for burns; negative βi indicates selection against burns. SP = spring,
S = summer, F = fall, W = winter, and LW = late winter. * indicates seasonal βi is different from
zero based on 95% confidence intervals.

(Figure 2). Stone's sheep most often used
younger burns (<3 years old), whereas elk
commonly used burns of all ages (1-28 years).

were more important than other cover classes
in every season for elk and rocky areas were
not of high importance (Figure 3B).

Even with this selection for burns and being
close to a burn, most locations of collared
Stone’s sheep were in rocky areas, in contrast
to elk that rarely used them. The relative
importance (use × availability scaled to 1.0) of
these two land-cover classes is shown in
Figure 3.
Prescribed burns were most
important to Stone's sheep in winter and late
winter. Rocky areas were always important,
especially during seasons when burns were
least important (Figure 3A). Prescribed burns

The highest probability of overlap in the
selection and use of burns by Stone’s sheep
and elk was in winter and late winter, but the
two species partitioned the landscape through
their differential use of elevation and
topography.
Stone's sheep always used
steeper slopes and higher elevations than elk,
and selected for rugged terrain. When elk
used steep slopes, they were typically at lower
elevations (Figure 4). When elk occasionally
used more rugged terrain, they also were at

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9

Figure 3. Seasonal importance (use × availability scaled to 1.0, x ± SE) of burned landcover classes (New burn, Burn grass, Burn shrub) and Rock/rock crust land cover for GPScollared female Stone's sheep and elk in the Besa-Prophet area in northern British Columbia
between 2010–2012. Averages from each individual in each season were used to calculate
means and standard errors. SP = spring, S = summer, F = fall, W = winter, and LW = late
winter

lower elevation than Stone’s sheep. Most
ungulates must balance the need to meet
nutritional requirements through forage with
the risk of predation. Availability of escape
terrain, consisting of solid-rock features or
talus slopes is a well-recognized component of
wild sheep habitat (Bleich et al. 1997,

10

Rachlow and Bowyer 1998). Stone's sheep
use rocky areas to reduce the risk of predation.
In the food-risk trade-off, food becomes
increasingly important from fall through late
winter (Walker et al. 2007) and Stone’s sheep
take advantage of the forage on prescribed
burns (Figure 3A). In spring during lambing,
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risk outranks food. As summer progresses,
lambs become less vulnerable and the
importance of food increases. Stone's sheep
show strong site fidelity and philopatry to
their seasonal ranges (Seip and Bunnell
1985b).
Elk also show site fidelity to particular ranges
(Craighead et al. 1972, Edge et al. 1986). We
expected that elk would travel long distances
to use new burns, but this was not the case.
Several collared individuals spent all year on
older burns, even when they had access to new
burns nearby.
The predator avoidance

strategies of elk rely on the ability to detect
danger at a distance, giving them time to
retreat to safer terrain when needed (White et
al. 2009). Prescribed burns increase visibility,
and the Burn shrub areas provide excellent
foraging opportunities for elk as well as some
cover. For both elk and Stone’s sheep,
grouping behaviour (outside of the
calving/lambing period) also serves as an antipredation strategy because larger groups
increase the ability to detect predators. We
observed largest groups of both species on
burns in winter.

Figure 4. Niche partitioning of elevation and slope ( x ± SE) by GPS-collared female
Stone's sheep and elk in the Besa-Prophet area of northern British Columbia.
Individual averages were calculated monthly and averaged across individuals to obtain
means and standard errors.
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11

Conclusions & Recommendations
Our findings provide insights into the shortterm vegetation dynamics and ungulate
response to prescribed fire in a mountainous
region of the northern Rockies. They also
provide a baseline for long-term monitoring of
the effectiveness and impacts of prescribed
burning in northeastern BC.
Winter
range
and
prescribed burning

season

for

Stone's sheep in the Besa-Prophet area showed
the highest use and selection for burns in
winter and late winter. This is consistent with
other studies for Stone's sheep (Walker et al.
2007) and bighorn sheep (Ovis canadensis;
Greene et al. 2012). Prescribed burning to
enhance Stone's sheep populations should
place conserving and enhancing winter and
late winter range as the highest priority. Peck
and Peek (1991) observed highest use of burns
by elk in drainages north of the Besa-Prophet
area during winter, and in our study, elk used
burns in every season. Even without higher
protein levels in late-winter forage, ungulates
wintering on burned grasslands have better
body condition due to increased foraging
efficiency and increased access to forage
(Hobbs and Spowart 1984, Seip and Bunnell
1985a).
Prescribed burning that targets winter range
should be conducted in spring.
Spring
burning results in greater enhancement of
above-ground production of herbaceous plants
suitable for ungulate forage (Owensby and
Anderson 1967). The conditions required to
burn green vegetation in summer make it
difficult to achieve the burn intensities
required to meet the objectives of enhancing

12

ungulate habitats, and fires are often more
volatile and harder to control (Hatten et al.
2012). Although there has been some success
from fall fires to increase habitat value
(Merrill et al. 1980), vegetation does not
rebound until the next spring, greatly reducing
forage availability for ungulates during the
initial winter after burning and increasing the
chance of soil erosion by wind and water
during the spring melt (Jourdonnais and
Bedunah 1990). Fall fires also are typically
larger and more intense (Holl et al. 2012).
Frequency of burning – based on
forage quality and quantity
The length of time that burned areas remain
beneficial to grazing ungulates is unknown.
When Stone's sheep used burns, they were
most often younger burns with increased
nutritional quality. Forage quality, however,
deteriorates with time (Van Dyke and Darragh
2007). Seip and Bunnell (1985b) reported that
the quality of forage on burned slopes that
were up to 9 years old and used by Stone's
sheep was not superior to that on unburned
slopes, but there were still increased lamb/ewe
ratios and fewer lungworm parasites on these
sites (Seip and Bunnell 1985a). Use of burned
sites by bighorn sheep was still higher than
unburned sites after 4 years even though
vegetation production leveled off (Peek et al.
1979).
Therefore, conducting prescribed
burns to increase forage quality and reduce
shrub cover every 5–10 years would appear to
benefit Stone's sheep.
This may not
necessarily be true for elk, which showed less
preference for the age of a burn. Other studies
though have shown that forage biomass
increases and persists for a longer time than
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forage quality (Singer and Harter 1996,
Sachro et al. 2005), which may be of most
benefit to elk.
Thus, there is a need for long-term monitoring
of plant response to fire in the Besa-Prophet
area. The permanent transects on the four
burns and four unburned areas (at Richards,
Townsley, Nevis, and Luckhurst sites) should
continue to be revisited to monitor longer term
changes in vegetation. Also, there are burns
of different ages (0–30 years old) in the BesaProphet area that researchers could use to test
changes in forage dynamics as burns age. The
locations of permanent transects and range
exclosures that we installed to measure longtern impacts of herbivore use are given in
Sittler (2013).
Size and aspect of prescribed burns
Slope position and size of a burn affect animal
use. To maximize benefits to both Stone's
sheep and elk, large prescribed fires should
periodically target south-aspect slopes or
similar areas known to produce high quantities
of forage. The Richards burn provided the
highest forage biomass and the large area
enabled largest congregations of animals.
Even though both Stone’s sheep and elk used
this burn in winter and late winter, they
partitioned their use of it spatially.
Implementing large burns from the valley
bottom to the alpine would enable both
species to benefit from the burn, and at current
population densities, minimize the potential
for competition.
Smaller fires result in lower amounts of
burned habitat, but increase heterogeneity on
the landscape. As demonstrated by high use
of the Luckhurst burn, small burns aimed to

enhance Stone's sheep should target westaspect sites with access to escape terrain.
West-aspect sites tend to have more moisture.
To achieve the desired result of reducing
shrubs and increasing forage quality,
prescribed burning on west-aspects should be
implemented late in spring to obtain high burn
intensities. The challenge with planning small
burns is that they may increase the probability
of overlap in use between elk and Stone's
sheep and the potential for competition by
funneling large groups of elk into a small area,
thereby reducing forage availability. In the
Besa-Prophet area, however, many of the
west-facing slopes have rocky outcrops and
talus scree slopes intermixed with vegetated
sections that fan outwards downslope. These
areas are less frequented by elk, especially
large groups of elk.
North aspects are usually snow-covered and
burning these slopes could not occur until late
in the summer because of heavy snow
accumulation.
These areas provide less
benefit to ungulates and if the objective is to
enhance ungulate habitats, burning northaspect slopes would be inefficient.
Dynamics
of
assemblage

the

large-mammal

There is a need for long-term monitoring of
animal response to fire in the Besa-Prophet
area. The findings of our study suggest that
there is not currently a conflict for space or
forage between Stone's sheep and elk, as they
appear to partition their use of the landscape
based on elevation, slope, and ruggedness.
However, we have not quantified the longerterm demographic effects of fire or changing
predator-prey dynamics. Additional studies
should focus on population estimates and

Sittler, Parker, Gillingham, Wheate & Heard  Effects of Prescribed Fire on Ungulates

13

distributions of target ungulates, primarily elk,
moose, and Stone's sheep.
Continued
increases in the elk population could increase
the potential for competition with Stone's
sheep if elk move into the traditional areas of
Stone’s sheep in response to the early seral
habitats created by fire, and the potential for
apparent competition (by facilitating the
increase of shared predators) even if elk do
not alter their distribution. There is some
seasonal overlap between elk and moose in the
Besa-Prophet area (Gillingham and Parker
2008) and if the elk population continues to
expand, it could potentially come at a cost, not
only to Stone's sheep but also to moose.
Caribou in the Besa-Prophet area appear to
avoid burned areas in all seasons (Gustine and
Parker 2008), but because they are a farranging species potentially affected by any
disturbance on the landscape, their
populations should also be monitored in light
of changes in predator-prey dynamics. Just
south of the Besa-Prophet area, the Sikanni
Valley is the northern boundary of the largest
free-ranging herd of plains bison (B. b. bison)
in BC. This bison population should be
monitored to determine the extent of its range
and to ensure that prescribed burning practices
do not substantially change patterns of use. If
the bison population expands northwards, it
may impact native grasses as well as compete
spatially with moose, elk, and Stone's sheep.

14

Management actions of prescribed fire
typically alter ungulate distributions. The
benefits of fire are likely facilitating numerical
and spatial expansion of elk, which now
provide the largest biomass of prey in the
Besa-Prophet
ecosystem.
Predator
populations are likely to increase in response
to the increasing elk prey base. Increased
wolf and grizzly bear numbers will affect
predator-prey dynamics (Milakovic 2008),
potentially increasing the risk of predation on
secondary prey species such as Stone's sheep,
moose, and caribou. Careful monitoring is
required to determine if the prescribed burn
program is enhancing or changing predation
opportunities.

NRESi Research Extension Note No. 9
July 2014

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Acknowledgments
We thank R. Woods for animal captures and implementation of prescribed burns, the pilots who
provided transport to field sites, and the many assistants who helped with vegetation sampling
and radio collar retrieval. Research was funded by the BC Habitat Conservation Trust
Foundation, W. Garfield Weston Foundation, University of Northern BC, Wild Sheep
Foundation, Wild Sheep Society of BC, Association of Canadian Universities for Northern
Studies, Northeast BC Wildlife Fund, and the Northern Scientific Training Program.

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