Wildlife and human recreationists in a Fort Collins, Colorado, natural area
Bonnie C. Greenwooda, Jennifer L. Valentineb, Tory C. Wilsona
a
b
Department of Fish, Wildlife, and Conservation Biology, Colorado State University
Department of Animal Sciences, Colorado State University
ABSTRACT
This study explores the impact of human presence on wildlife species in Bobcat Ridge
Natural Area and will serve as a foundation for future studies of long term wildlife and human
trends. Eight camera traps were located within Bobcat Ridge Natural Area, four were located
on-trail and four were located off-trail. Photos of wildlife and humans were enumerated by
camera and used as the basis of analysis. Human and wildlife spatial and temporal use of Bobcat
Ridge Natural Area was not evenly distributed. Bobcat, coyote, and cottontail rabbit photos
were primarily during the night and at on-trail cameras. Black bear and mule deer photos were
primarily during the day and at off-trail cameras. Humans are only allowed in the natural area
during the day. These results suggest a negative correlation between human presence and
wildlife presence, meaning that as human presence increases wildlife presence decreases. A
linear regression comparing human presence to wildlife presence exhibited a significant yet only
slightly negative relationship between the number of human photos and the number of wildlife
photos at on-trail cameras. This suggests that recreational use of Bobcat Ridge Natural Area
may be adversely impacting wildlife but only to a limited extent. We suggest the impacts of
human recreationists on wildlife species is site specific due to the varying results of this study
and other such studies. We also suggest a need for long-term studies of the impact of human
recreationists on wildlife due to seasonal and annual variations in wildlife and human activity.
Keywords: Natural areas, Camera traps, Wildlife, Recreation
1. Introduction
Across the globe the world population of humans is dramatically increasing;
consequently, urban sprawl is depleting wildlife habitat and threatening wildlife populations;
Wilcove et al. (1998) found habitat destruction and degradation to be the primary threat to
biodiversity, contributing to the endangerment of 85% of the species investigated in their study.
Colorado is no different; the Colorado Department of Local Affairs reports that between 2000
and 2007 the population of Larimer County increased by 12% with the population of Fort Collins
increasing by 10% and that of Loveland increasing by 23% (Compass of Larimer County, 2007).
As the population of the northern Colorado Front Range has increased, there has also been an
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increase in the use of protected recreational areas, such as Bobcat Ridge Natural Area. The Fort
Collins Natural Areas Program reported that educational program attendance at Bobcat Ridge
Natural Area was up 251% over 2007 (CPRE, 2009). While local involvement and use of
protected areas can be beneficial to wildlife conservation, it can also pose serious threats to
wildlife if not closely monitored. As an increasing number of recreationists utilize natural areas,
wildlife population dynamics must be monitored and management guidelines clearly constructed
and enforced to conserve and protect biodiversity (Knight and Gutzwiller, 1995).
According to Losos et al. (1995), of all resource extraction activities, outdoor recreation
is the second leading threat to species in the United States. Studies also report that pedestrians
elicit a greater response from wildlife than other recreationists because they retain the
appearance of the human form (Freddy et al., 1986; MacArthur et al., 1982). However, each
wildlife species can have a different response to recreation, and their response may vary with the
type of recreation (Knight and Gutzwiller, 1995). George and Crooks (2006) found bobcats
(Lynx rufus) and coyotes (Canis latrans) to be reactive to recreation; both species exhibited
spatial and temporal displacement in response to human recreation. Bobcats and coyotes
exhibited restricted activity in areas with high levels of recreation. Although bobcats and
coyotes respond to human activity by altering their behavior, they are able to persist in areas with
frequent human activity (Tigas et al., 2002). Even though Taylor and Knight (2003) found mule
deer (Odocoileus hemionus) to be behaviorally responsive to human recreation, George and
Crooks (2006) did not detect a definitive pattern of mule deer avoidance of human recreation.
However, mule deer had decreased daytime detection probabilities with increased human
recreation (George and Crooks, 2006). Black bears (Ursus americanus) may shift their activity
to crepuscular and nocturnal hours when diurnal activities are disturbed by either humans or
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brown bears (Ursus arctos) (Reimchen, 1998), but few studies have been published to asses the
impact of human recreation on black bear behavior and activity (Beckmann and Berger, 2003).
Beier (1995) found juvenile dispersing mountain lions (Puma concolor) to move towards dark
horizons, away from man-made light in a fragmented habitat. He also documented mountain
lions using dirt roads and hiking trails as traveling paths, showing no aversion to trail-users.
Mountain lion distribution and habitat use was found to be limited by human activity such as
human settlements and roads in central Mexico (Monroy-Vilchis et al., 2009).
These reports advocate the need for further study of the impact of human recreation on
wildlife. This study explores the impact of human presence on wildlife species in Bobcat Ridge
Natural Area. This will serve as a foundation for future studies of long term wildlife and human
trends.
2. Methods
2.1. Study Site
Bobcat Ridge Natural Area is located near the town of Masonville, west of Fort Collins,
Colorado. The area encompasses 2,606 acres, including 160 acres of US Forest Service patches
scattered throughout the natural area. Grassland, shrubland, and pine forests are the dominant
habitat types ranging from 5,000 to 7,000 feet in elevation. The average reported high and low
temperatures in July are 87°F and 54°F, respectively. The mean annual precipitation for
Masonville, Colorado is 17 inches. In 2000, the Bobcat Gulch fire decimated 1000 acres of the
western portion of Bobcat Ridge Natural Area, burning two-thirds of the forested area. After the
City of Fort Collins acquired Bobcat Ridge Natural Area in 2003, it was opened to the public in
fall 2006. Visitor use of the area includes hiking, walking, running, mountain biking, horseback
riding, wildlife viewing, interpretive walks, picnic sites, and ADA compliant trails. The trail
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system of Bobcat Ridge Natural Area is composed of 5 main trails, Valley Loop Trail, Eden
Valley Spur, Ginny Trail, D.R. Trail, and Power Line Trail. Equestrians are restricted from the
Ginny Trail and the Powerline Trail. Mountain bikers are restricted from the D.R. Trail. The
Ginny Trail was not included in this study as no cameras were placed along this trail.
2.2. Camera Trap Data Collection
Camera traps are an economical, effective noninvasive surveying technique used to study
wildlife populations, especially cryptic carnivores (Balme et al., 2009). Eight Cuddeback
Capture Digital Scouting Cameras were located within Bobcat Ridge Natural Area (Non Typical,
Inc., Park Falls, Wisconsin). Four cameras were located on-trail and four cameras were located
off-trail. Cameras were paired with one camera on-trail and one camera off-trail along the four
trails considered in this study, including Valley Loop Trail, Eden Valley Spur, Powerline Trail,
and D.R. Trail (Figure 1).
Fig. 1. Map of camera locations within Bobcat Ridge Natural Area.
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Six of the cameras were setup on June 4, 2009 and the remaining two cameras (007 and
008) were setup on June 18, 2009. At the time of setup, geographic coordinates of each camera
location were recorded in addition to a brief description of the location specifying the direction
the camera faced. Cameras were secured to trees using Cuddeback Bearsafe boxes and padlocks
to prevent human and wildlife tampering or theft (Non Typical, Inc., Park Falls, Wisconsin).
The camera time delay was set at 30 seconds on each camera and remained at that setting
throughout the study. Cameras were checked weekly starting June 6th 2009 and ending August
28th 2009; there was a total of fourteen camera checks. Cameras 001 through 006 each had a
total of 86 camera trapping days, while cameras 007 and 008 each had a total of 72 camera
trapping days. There was a total of 660 camera trapping days in this study. During camera
checks, weather, wildlife sign such as tracks and scat, date and time of check, the number of
photos per camera, and any other comments were recorded. If batteries were replaced, then this
was also indicated on the data sheet; however, the batteries did not need to be replaced during the
study. The two gigabyte SD card in each camera was replaced with a new empty card. After
returning from the field, photos were downloaded to a computer from each SD card and stored
by camera location and check date. These SD cards were then cleared and used for the following
camera check. Photos were enumerated by wildlife species and human trail-user type. Wildlife
photos were recorded individually with camera location, date, and time being noted.
2.3. Data Analysis
All data analyses were conducted using Microsoft Excel 2007. The focal species
analyzed individually in this report include bobcat, coyote, black bear, mule deer, elk (Cervus
elaphus), and cottontail rabbit (Sylvilagus floridanus). All wildlife photos captured by each
camera were summed. The percentage of wildlife photos by species at each camera was
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calculated (i.e. 37.9% of bobcat photos were at camera 002). Additionally, the percentage of
wildlife photos by species during the day (0600-1959 hours) and night (2000-0559 hours) was
calculated (i.e. 17.2% of bobcat photos were during the day). Finally, the percentage of wildlife
photos by species at on-trail and off-trail cameras was calculated (i.e. 100% of bobcat photos
were at on-trail cameras).
Human photos were also analyzed to integrate human use of Bobcat Ridge Natural Area
into this study. The percentage of all human photos captured by each camera was calculated (i.e.
6.8% of all human photos were at camera 002). A linear regression was conducted in order to
assess the impact of human presence on wildlife presence. For this analysis, all human trail-user
types were combined into one human category. The number of human photos per day at each
on-trail camera was determined and used as the independent variable. Also for this analysis all
wildlife species detected in this study were grouped into one general wildlife category. The
number of wildlife photos per day at each on-trail camera was determined and used as the
dependent variable. All four on-trail cameras were included in this analysis, and each data
pairing in the linear regression represents a unique camera trapping day. A linear regression was
conducted to test if as the number of human photos increased, the number of wildlife photos
decreased.
3. Results
3.1. Camera traps
Throughout the study a total of 5,265 photos were captured. The wildlife species that
were detected by the camera traps include: bobcat, coyote, black bear, mule deer, cottontail
rabbit, elk, turkey (Meleagris gallopavo), bighorn sheep (Ovis canadensis), striped skunk
(Mephitis mephitis), fox squirrel (Sciurus niger), and other bird species. Mountain lions were
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not detected during this study. All photos were used in analyses even if there were multiple
photos of the same human or animal.
Both human and wildlife spatial use of Bobcat Ridge Natural Area was not evenly
distributed (Figure 2). Camera 008 located on Valley Loop Trail had the lowest percentage of all
wildlife photos (6.99%) and the highest percentage of all human photos (46.21%). Camera 002
located on D.R. Trail had the highest percentage of all wildlife photos (27.39%) and the lowest
percentage of all human photos of the on-trail cameras (6.97%).
Fig. 2. Percentage of all wildlife photos and all human photos by camera in Bobcat Ridge
Natural Area. * on-trail camera
Temporal use and spatial use of Bobcat Ridge Natural Area by wildlife species was not
even (Table 1). Bobcat, coyote, and cottontail rabbit photos were primarily during the night and
at on-trail cameras. Black bear and mule deer photos were primarily during the day and at offtrail cameras.
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Table 1
Temporal and spatial use of Bobcat Ridge Natural Area by wildlife species.
Species
Bobcat
Coyote
Black Bear
Mule Deer
Cottontail Rabbit
Elk
Temporal Use
% of Species
% of Species
Photos During Photos During
the Day
the Night
(0600-1959
(2000-0559
hours)
hours)
17.24
82.76
18.97
81.03
87.5
12.5
81.45
18.55
2.82
97.18
77.27
22.73
Spatial Use
% of Species
Photos at OnTrail Cameras
% of Species
Photos at OffTrail Cameras
100
74.14
12.5
37.45
100
18.18
0
25.86
87.5
62.55
0
81.82
All day photos and all night photos of bobcats and cottontail rabbits were at on-trail
cameras (Table 2). The majority of coyote photos at night was at on-trail cameras and during the
day was at off-trail cameras; mule deer photos also showed this trend but not as strongly at night.
Both night and day photos of black bear and elk were mostly at off-trail cameras.
Table 2
Each species’ night photos and day photos expressed as percentages at on-trail and off-trail
cameras in Bobcat Ridge Natural Area.
Night (2000-0559 hours)
Day (0600-1959 hours)
% of Species
% of Species
% of Species
% of Species
Species
Night Photos
Night Photos
Day Photos
Day Photos
On-trail
Off-trail
On-trail
Off-trail
Bobcat
100
0
100
0
Coyote
87.23
12.77
18.18
81.82
Black Bear
0
100
14.29
85.71
Mule Deer
58.82
41.18
32.59
67.41
Cottontail Rabbit
100
0
100
0
Elk
40
60
11.76
88.24
The linear regression comparing human presence and wildlife presence at on-trail
cameras suggests a significant and slightly negative relationship (β1 = -0.0296, F = 15.28, p =
<0.05, R2 = 0.0464). It is acknowledged that there may be a lack of independence between
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camera trapping days at an individual camera. The residual plot associated with the linear
regression exhibits a slight pattern; however, for the purpose of this study, independence was
assumed.
4. Discussion
Camera 008 had the highest percentage of human photos but the lowest percentage of
wildlife photos of all cameras. Camera 002 had the highest percentage of wildlife photos of all
cameras but the lowest percentage of human photos of the four on-trail cameras. These results
suggest a negative correlation between human presence and wildlife presence, meaning that as
human presence increases wildlife presence decreases. Bobcat, coyote, and cottontail rabbit
photos were predominately at night and at on-trail cameras. All three of these species are
naturally nocturnal. Because humans are not allowed in Bobcat Ridge at night, these species
appear to be utilizing the trails in the absence of humans. Black bear, mule deer, and elk were
mostly active during the day and at off-trail cameras. These species are naturally diurnal but
might not be using trails in order to avoid humans. Additionally, the linear regression exhibited
a significant yet only slightly negative relationship between the number of human photos and the
number of wildlife photos at on-trail cameras. This suggests that recreational use of Bobcat
Ridge Natural Area may be adversely impacting wildlife but only to a limited extent.
4.1. Conservation Implications and Future Studies
We suggest the impacts of human recreationists on wildlife species is site specific due to
the varying results of this study and other such studies (George and Crooks, 2006; Knight and
Cole, 1995; Tigas et al., 2002; Taylor and Knight, 2003; Reimchen, 1998; Beckmann and
Berger, 2003). This holds important implications for species of conservation concern due to
differences in levels of recreation, types of recreation, personalities of wildlife individuals,
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habitat types, and history of human use between habitat areas. We also suggest a need for longterm studies of the impact of human recreationists on wildlife due to seasonal and annual
variations in wildlife and human activity. This study presents data from one summer; however,
this study served as the initial phase of an on-going long-term study known as Communities,
Cameras, and Conservation (CCC) through the Rocky Mountain Cat Conservancy. Community
education and involvement in local conservation is a key feature of CCC and has the potential to
increase recreationists’ awareness of their effects on wildlife. Taylor and Knight (2003) found
recreationists to be ignorant of their own impacts on wildlife. People have to be aware of their
own impacts on the environment in order to minimize those impacts. More research is needed to
further understand and minimize the impacts of human recreation on wildlife species.
Acknowledgements
We would like to thank the City of Fort Collins Natural Areas Program for making this
study possible. We are also indebted to the Rocky Mountain Cat Conservancy for the use of
their cameras and their expertise and guidance.
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