Can photograph identification be a useful tool in the identification of
Bighorn Sheep (Ovis canadensis) at the
Kootenay Pass Feeding Station, British Columbia?

Kara Laurie-Serruys
RFW 271, Selkirk College

Faculty Advisor: Lui Marinelli PhD
April 5, 2020

Disclaimer
The contents provided on the following pages are student work produced as part of the written
evaluation in the diploma program in the School of Environment and Geomatics, Selkirk
College, Castlegar, British Columbia, Canada. This work obtained a minimum assessment grade
of “C” (60%) and met the requirements of the assignment for which it was completed.

The author has provided written permission to include the following academic work in the
Selkirk College Online Repository (SCOLR) and retains full copyright over their work. Canadian
Copyright law applies to use of this work.

1. Abstract
The use of photo-identification has been applied to marine mammals such as sea otters (Enhydra
lutris), Humpback whales (Megaptera novaeangliae) and have been applied to Polar Bear (Ursus
maritimus). Photo identification is the method of taking photographs of a universal marking on a
species and using those to identify members of the herd or grouping without being invasive.
With the photographs that are begin collected by these studies, researchers can compile these
into a database and all researchers would be able to have access to these photos for identification
in the field. I wanted to use this method of identification on Bighorn sheep (Ovis canadensis) and
determine is this method can be used on wild herds, as well as a way to monitor a species
population from a distance. The use of photo-identification on Bighorn sheep will require taking
photographs of the rumps and the heads of each member of the herd that is located at the
Kootenay Pass feeding station. This herd have been coming to the station for about 40 years and
they have become accustom to having humans near, which makes this herd a perfect subject for
this study. By testing this method on this herd, we can determine if this technique of
identification can be used on wild herds and different species in the long run.

2. Acknowledgements
I would like to thank the following individuals for their assistance and guidance
throughout this research project. I firstly would like to thank my research partner Sarah Beaudoin
and my faulty advisor, Lui Marinelli. Secondly, I would thank to say thank you to my applied
Research professor Brenda Beckwith for her writing guidance and knowledge. The last group I
would thank to acknowledge would be the Nelson District Rod and Gun Club for their
hospitality at the Kootenay Pass Feeding Station.

3. Introduction
The identification of specific animals in a herd or pod has been difficult for wildlife
researchers due to the lack of reliable methods and techniques. Depending on the species, there
have been tactics used such as collars, tracking chips, tagging, and tattoos to mark and identify
wildlife (Anderson et al. 2010). These methods were commonly viewed by the public, and other
researchers, as invasive. When putting tracking equipment on animals, technicians usually have
to sedate the animal which can cause medical complications and, in some cases, even death
(Anderson et al. 2010). For example, internal trackers can cause damage to the internal organs
when they are implanted, tattoos can get infected, and collars can get stuck on tree branches and
snares (Anderson et al. 2010). Using more non-invasive approaches, such as the use of unique

animal markings for identification, can monitor animal health and give researchers opportunities
to leave the animals undisturbed for study purposes.
The use of photo-identification strategies began appearing in marine mammal studies
over the last 20 years. Studies that have used unique markings on animals include the
observations of scaring on the noses of sea otters (Enhydra lutris) and spot patterns on the shells
of leatherback sea turtles (Dermochelys coriacea) (Gomez-Salazar et al. 2011). In 2006, Adam
et al. (2006) used markings on the tail and dorsal fins of bottlenose dolphins (Tursiops truncates)
to identify individuals of the pod. Scaring and coloring on the trunk of the body in most marine
mammal species are used to determine the correct identification. Computer algorithms and
databases are being created to cross-reference the images to identify a specific member of the
species (Adam et al. 2006). Speed et al. (2007) determined that the use of computer algorithms
can significantly increase the positive matches in identifying individual species. One challenge in
using computer-based programs, according to Speed et al. (2007), is ensuring the photograph is
taken in the correct lighting and has the proper spacing and camera angles. A false identification
can result if the image is not in the correct angle or light. (Speed et al.2007).
Building on the success of marine mammal photo-identification, researchers are starting
to implement these methods with land-based animal species. For example, Anderson et al. (2010)
cross-referenced photographs showing spot and whisker patterns on polar bears (Ursus
maritimus) to identify individuals using face recognition software. Although there is little
documented information about bighorn sheep (Ovis canadensis), the species has distinguishable
rumps that could be the main marker in identification, although scars and noticeable marks on
the horns can also be considered as unique features.
A feeding station was located in the Kootenay Pass area of British Columbia was created
over 40 years ago to influence the behavior of a local herd of Rocky Mountain bighorn sheep and
keep them from crossing the highway and to monitor the health of the herd members. Bighorn
sheep are known to stay in mountain areas with grassy slopes, alpine meadows, and rocky cliffs.
A feed station can persuade the bighorn sheep to remain in their natural habitat and can hopefully
help with increasing the current number of members in the herd. This feeding station is also open
to the public, which can help organizations and researchers raise awareness about bighorn sheep
and wildlife in general.

The bighorn sheep arrive at the feeding station at the start of each winter and are fed three
times a week by local volunteers from Nelson and Salmo and wildlife organizations in the area.
According to records taken by volunteers, the herd had a population of about 30 bighorn sheep
about 40 years ago but, currently, there are only 15 that are present.
In my research project I will determine the viability of applying more photo-identification
studies to land mammals by tracking the bighorn sheep herd through observations of their
markings. All the photos in this research paper, I have taken personally unless credited
otherwise. To address this research goal, I will conduct the following objectives:
•

Use repeat photo-identification to identify members of the bighorn sheep
population at the feeding station.

•

Determine if universal markers on animals can be used for identification,

4. Methods
4.1 Study Site
The feeding station is located on Highway 3, on the west side of Kootenay Pass
approximately 10 kilometers from Salmo, British Columbia (BC). The Kootenay Pass feeding
station is at approximately 1775 meters in elevation and in the Interior Cedar Hemlock dry and
warm (ICHdw1) Biogeoclimatic Ecosystem Classification (BEC) Unit (Mackillop and Ehman
2016). This area is known to have cold temperatures and measurable amount of snow in the
winter (Avalanche Canada.2020). The dominant tree species in this area are lodgepole pine
(Pinus contorta), Douglas-fir (Pseudotsuga menziesii), and western red cedar (Thuja plicata).
Mammals that inhabit this area are mule deer (Obocoileus hemionus), cougars (Puma concolor),
and coyote (Canis latrans). The feeding station is positioned about 200 meters above the
highway following the trail on the north side of the highway. The trail from the road to the
feeding station is about 150 meters in length.
4.2 Data Collection
Prior to collecting field data, my research partner and I reviewed and collected information based
on similar studies on photo-identification methods. We also meet with our faculty advisor, Lui
Marinelli, who has extensive experience in wildlife and methods for identification. This gave us

insight on how to correctly take photos of the animals, and successful identity each member of
the herd every week.
My research partner, Sarah Beaudoin, and I scheduled our field collection days to occur
on every Saturday of the winter season starting on December 28, 2019 and containing until
February 8, 2020. We chose Saturday mornings at 10:00 am because this is one of the scheduled
feeding days, and it gave us a longer period of time to collect the photographs compared the
weekday feedings and managing classes. The drive to the feeding station did pose a challenge
on some of the days, due to road closures or unsafe driving conditions. After arriving at the
highway pullout, we then accessed the site on foot by following the set trail to the station.
After we feed the sheep, we started collecting photographs using two cameras. We
singled out the most distinctive members and documented these first. For example, the rams
were photographed first because there were only two of them and one of them was collared,
making it easy to tell the difference between the two. The herd is wild so they did show signs of
stress and fear when we were moving around, but they did get used to our presence after some
time. We designated tasks between the two of us to ensure we didn’t miss anything as well as
reducing the human factor on these sheep. In regards to reducing the human factor on these
sheep, we don’t want this herd to grow too comfortable with people because that can cause
higher issues with roadkill, hand feeding and petting these wild animals. We had two cameras
between us so Sarah stayed on one side of the herd, and I was on the other, and we
communicated throughout which herd member we took photos of and which ones we still
needed. We collected photos of the rumps and heads of each member. We started with the rams,
then worked on the four lambs that were present and then moved to the eight ewes. The ewes
were more of a challenge to take photos of because many of them are similar and they move
around a lot more compared to the rams and the lambs. One of the ewes was collared as well,
and this was where we started when taking photos of the ewes. We left the site after we were
confident that all the members of the herd were documented.
During the following week we would compare the photos working though the sheep in
the same way as we did in the field; the rams were matched first, then the lambs, and then the
ewes. Unique file names were created to accurately document each bighorn sheep and was added
to a Microsoft Excel spreadsheet to summarize the data for each of the weeks. The first week that

we compared the photos, we used photos taken from previous years to determine if the sheep
during the 2020 season match the ones documented in the past.

5. Results
5.1 Data Analysis
After each of the field days, we planned a day of the week to sit down together and go
through the photos from each week and match the rumps to each of the heads. There were a
couple weeks where a there was one or more sheep absent, and there was a day where some of
the rumps didn’t get photographed. At the end of the project, we used data and photographs from
prior years to determine if there were members of the herd present for more than one study
period. We did find that working with two cameras during the field collection, ensured that most
or all the sheep would be photographed and documented. We collected data every Saturday over
six weeks from December 28, 2019 to February 8, 2020.
How many in herd and relative breakdown were first. There were 8 ewes (57% of the
herd) that were documented throughout the study period (Table 1). Because we already had the
understanding that there were 8 ewes, 2 rams and 4 lambs, we could notice if one was absent. All
ewes were absent on 02.01.2020, but they returned to the feeding station in the next week.
Although we found that, as we moved through the study weeks, the ewes were becoming much
easier to identify, there were multiple ewes that looked very similar and we had to use more of
the horn shaped or facial marking to determine the correct herd member.
There were only two rams in the herd (percent of total) and one of them was collared and
tagged (Ram 2) (Table 2), making their identification quick. one of the rams was at the station
during the site visit when no ewes were present.
There were four lambs that were present during majority of the field study period. These
lambs were young, and they were easy to identify because each lamb on had a specific horn
pattern and different sized and proportioned bodies. These lambs were found to be more anxious
when we were around, making the photographs blurry at times, causing the identification process
at the office to be harder.

Comparing our photographs to those taken in the previous year, we found multiple
matches between the photographs, namely there were lambs photographed last year that are now
ewes during our research project. When comparing previous data to our data, we used the
number system that they went by due to we knew what our sheep looked like compared to the
herd members during the past years. The ewes did show come difficulty in correctly identify in
regards to there was nine in the past study year and our year only had eight (Table 3).
In addition, there were four rams in the past year compared to this year where there was
only two (Table 4). 2 out of 4 of the rams were collared during the 2018/2019 study period and
we only had one collared. The lambs had the same number during both of the study periods
(Table 4).

6. Discussion
6.1 Interoperating the data
Through our research we were able to show that bighorn sheep can be identified with the
photo identification tool. With using the rumps as identification tools, we are looking at the
pattern of the brown marking going down the center as well as the size of the white patch that
can cover a small section of the back end or a large portion and down to the legs. It became easy
to identify the sheep in the field because we (1) compared the photos taken each week and, (2)
compared the photos to the herd on site. The differences between the herd members much easier
to observe as the study days continued. We were able to positively identify the rams because
there were only two of them present in the herd and both rams had unique marking on the rump
sections. Furthermore, one of the rams had unique scaring on the face (Figure 1) and the other
ram was collared with a GPS tracking box (Figure 2). After looking at the photographs that were
taken last year, and using the key marking and features associated with each ram, we can say
with certainty that the rams identified in 2019 were present in the herd in 2020.
The ewes were all similar in size making their identification more challenging. One of the
ewes was collared and tagged. As with all the sheep we looked for noteworthy and obvious
markings on the rumps to aid in identification. My research partner and I, for example, noticed
that one of the ewes had a shape of a standing bird on the rump (Figure 3). However, for many of
the sheep, the patterns on the rumps were not enough for a positive identification. We also
targeted the head and horn patterns. One ewe had a very straight pair of horns, which is

uncommon. There were three ewe that looked very much alike the rumps were similar in shape
and size and the heads had similar marking and horn lengths. We usually saved these ewes for
last because it was more of a “process of elimination” to correctly identify them. We correctly
matched these three members after all the pictures were taken and we compared the photos to the
previous weeks.
There were four lambs present and they were all very similar in size and horn length. The
rumps on these lambs did have a large amount of fur which made it seem like the rumps were
constantly changing through the field season. The increase in snow would build up on the backs
of the lambs and cover some of their rump as well as when the lambs were wet it affected the
looks of the rump patter. We found that the use of their heads played a key role in the
identification of these members. My research partner and I did notice that one lamb seemed to
have a “happy” facial expression during all the weeks of our survey, and this lamb was correctly
identified each week with photos and in the field by tracking his “smile.” (Figure 4). We found it
easier to find a key characteristic on each lamb that we could associate to an object or mood and
although this wasn’t the scientific way that we wanted to use for this project, it helped us in
correctly identifying each of these four, and it helped us study the rumps more because we
already were able to match these lambs to the pictures each week by just the heads and their
behavior.
To ensure that we correctly identified each member of the herd at the end of the field
period, we compared our results to the results of the previous researchers. We did understand
that there are going to be different members each year, but we did have two rams, six ewes and 2
lambs that were present during the 2018/2019 research year and the 2019/2020 research year.
The rumps and head between the members that were present during these two years didn’t
change at all between the years, and all the photos that were compared matched to the same ones
that we had positively identified.

7. Conclusion
Photo-identification is a useful method in identification of many species and this method
is growing and adapting with each study that has used it. This study that was conducted on
Bighorn sheep and my research partner and I found that it was one of the best and effective ways
of monitoring the herd throughout the winter months when they are at the feeding station on

Kootenay Pass. Being able to test our theory on photo-identification on the Rocky Mountain
Bighorn Sheep herd showed us that it is possible to use this method on the sheep and the next
step would be to conduct this study from a farther distance with wild herds.
There were a handful of limitations for this study and the main one was the traveling to
the site. There were days when the roads were closed due to unsafe conditions and there was a
day when one of us had vehicle complications that limited our time and myself getting to the
station. Other limitations were not having extra batteries for a camera to take the photographs, or
when they malfunctioned due to the cold weather.
At the end of the study we have recommendations for future studies that relate to photoidentification. For the limitation with driving and mechanically issues that occurred, carpooling
and traveling with other researchers can help reduce that limitation. The other main limitation
that we had was malfunctions and battery deaths of the cameras. The main recommendation that
my research partner and I can make would be to have an extra camera and multiple extra
batteries in the field.

8. Reference
Adams JD, Speakman T, Zolman E and Schwacke LH. 2006. Automating Image Matching,
Cataloging, and Analysis for Photo-Identification Research. Aqua Mamm. 374-384. Doi:
10.1578/AM.32.3.2006.374
https://www.researchgate.net/profile/Jeffrey_Adams5/publication/250020517_Automatin
g_Image_Matching_Cataloging_and_Analysis_for_PhotoIdentification_Research/links/0
0b495335708413dc7000000.pdf
Anderson C, Niels Da Vitoria Lobo, Roth JD, Waterman JM. 2010. Computer – Aided PhotoIdentification System with an Application to Polar Bears based on Whisker Spot Patterns.
Jour Mamm. 6(16): 1350-1359. https://doi.org/10.1644/09-MAMM-A-425.1
Gomez-Salazar C, Trujillo F and Whitehead H. 2011. Photo-identification: A Reliable and NonInvasive Tool for Studing Pink River Dolphins (Inia geoffrensis). Aqua Mamm. 37(4)
472-485. Doi: 10.1578/AM.37.4.2011.
http://whitelab.biology.dal.ca/hw/Gomez_photoID_Aquatic_mammals.pdf
Mackillop DJ and Ehman AJ. (2016). A Field Guide to Site Classification and Identification for
Southeast British Columbia: The South-Central Columbia Mountains. Land Manage
Book. 70(1).
Schoenecker KA, Watry MK, Ellison LE, Schwartz MK, Luikart G. 2015. Estimating Bighorn
Sheep (Ovis canadensis) Abundance using Noninvasive Sampling at a Mineral Lick
within a National Park Wilderness Area. West North Amer Nat. 75 (2): 181-191.
Speed CW, Meekan MG, Bradshaw C. 2007. Spot the Match- Wildlife Photo- Identification
using information theory. Front in Zoo. 4 (2)
https://frontiersinzoology.biomedcentral.com/articles/10.1186/1742-9994-4-2 doi:
10.1186/1742-9994-4-2.

Table 1: Ewes present at the Kootenay Pass Feeding Station, from December 28 2019 to
February 8 2020.
Field days
12.28.2019
01.11.2020
01.18.2020
01.25.2020
02.01.2020
02.08.2020

Ewes Present
1
yes
yes
yes
yes
no
yes

2
no
yes
yes
yes
no
yes

3
yes
yes
yes
yes
no
yes

4
yes
yes
yes
yes
no
yes

5
yes
yes
yes
yes
no
yes

6
no
yes
yes
yes
no
yes

7
yes
yes
yes
yes
no
yes

8
yes
yes
yes
yes
no
yes

Table 2: Rams and Lambs Present during the field study weeks at the Kootenay Pass Feeding
Station
Field days
12.28.2019
01.11.2020
01.18.2020
01.25.2020
02.01.2020
02.08.2020

Ram Present
1
yes
yes
no
yes
yes
yes

2
yes
yes
yes
yes
no
yes

Lambs Present
1
yes
yes
yes
yes
no
yes

2
no
yes
yes
yes
no
yes

3
yes
yes
yes
yes
no
no

4
no
yes
yes
yes
no
yes

Table 3: Comparing Ewe members during the 2018/2019 study and the 2019/2020 study period
at the Kootenay Pass Feeding Station
Study year
2018/2019
2019/2020

Ewe
1
yes
yes

2
3
yes yes
no yes

4
yes
yes

5
yes
yes

6
yes
yes

7
yes
yes

8
yes
no

9
yes
maybe

Table 4: Comparing Ram and Lamb members during the 2018/2019 study and the 2019/2020
study period at the Kootenay Pass Feeding Station
Study year
2018/2019
2019/2020

RAM
1
yes
no

2
yes
no

3
yes
yes

4
yes
yes

LAMB
1
yes
yes

2
yes
yes

3
yes
no

4
yes
no

Figure 1: Ram 1, unique scaring on the face (Photo: Sarah Beaudoin)

Figure 2: Ram 2, collared and GPS tracker

Figure 3: Ewe 2, rump that has a “bird” outline on the rump (Photo: Sarah Beaudoin

Figure 4: Lamb 3, seemed to have a “happy” behaviour