YELLOWSTONE COUGAR PROJECT
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
YELLOWSTONE
COUGAR
PROJECT
2014 Annual Report
Since their return in the 1980s, cougars (Puma concolor) have
thrived in the northern portion of Yellowstone National Park and
nearby areas of Montana. These large cats coexist and compete
with grizzly bears (Ursus arctos), black bears (Ursus americanus),
and wolves (Canis lupus) for space and food. Following an 8-year
gap in research, a new study is in place to evaluate the current
abundance, distribution, and ecological influence of Yellowstone’s
charismatic and secretive big cat. The following report describes
this past season’s field efforts and discoveries.
Yellowstone Cougar Project
BACKG ROUN D
As predators, cougars play an important role in the structure and function of ecosystems. Knowledge of
cougar abundance and distribution is fundamental for evaluating the ecological consequences of their
presence on the landscape. Monitoring their population size and trends in a given area has proven
challenging without intensive marking and radio-collaring efforts. Telemetry efforts are informative, but often
labor intensive and expensive. Other methods such as helicopter snow-track counts, ground track counts, and
analyses of harvest structure are poor predictors of cougar population size. Noninvasive genetic sampling
methods are growing in application as a way to (1) identify species, sex, and individuals, (2) estimate
abundance and population growth rates, (3) quantify distribution, and (4) examine patterns of genetic
population structure of various carnivores. Further, developments in molecular technology provide genetic
information that can be used to determine behavioral parameters such as home range size, individual habitat
preferences, and even some forms of social interactions.
Cougar research in Yellowstone National Park has
incorporated a variety of the aforementioned methods to
understand the ecology of this top carnivore following their
natural recovery to the park in the 1980s. Two phases of
intensive cougar research occurred between 1987 and
2006 and provided a broad understanding of cougar
ecology, predation, and population dynamics prior to and after wolf reintroduction in 1995 and 1996
(Murphy 1998; Hornocker & Negri 2010, Ruth et al. in press). These studies estimated the minimum number of
cougars known alive by radio collaring individuals and conducting snow tracking surveys in northern
Yellowstone. Prior to wolf reintroduction (1987-1993), this region was occupied year-round by an estimated
15 to 22 cougars, including adults, subadults, and kittens. There were 26 - 42 cougars after wolf
establishment (1998-2005; Ruth et al. in press).
Page 1
Yellowstone Cougar Project
To evaluate the efficacy of noninvasive DNA sampling methods for monitoring Yellowstone cougars,
systematic snow-tracking surveys were conducted during 2003 to 2005 to collect hair and scat samples for
generating individual genotypes (Sawaya et al. 2011). Backtracking cats in snow to bed sites and natural
hair snags such as branch tips and thorn bushes was an efficient, reliable method for noninvasively sampling
genetics. Over a 2-year sampling period, 12 of 14 (86%) radio-collared individuals in the area were
detected, proving these methods to be successful. These findings demonstrated the utility of noninvasive survey
methods as a low-cost, long-term, population-monitoring tool for cougars.
Colby Anton, Yellowstone
Cougar Project field technician
and graduate student,
searches for cat tracks and
any DNA samples left behind.
Beginning in January
2014, we initiated a new
phase of cougar research in
northern Yellowstone. This study
is designed to build off
previous efforts to help address two important needs for understanding cougar ecology. First, cougar
population size estimates are needed so that cougar population dynamics and kill rates can be incorporated
when assessing the combined effects of large carnivores (wolves, bears, and cougars) in limiting or regulating
the northern Yellowstone elk (Cervus elaphus) population, as well as other ungulates residing in and near the
Park. Second, northern Yellowstone serves as a valuable source for cougars emigrating to other areas in the
larger Greater Yellowstone Ecosystem (Ruth et al. 2011). Periodic estimation of cougar population size,
growth, and distribution, in conjunction with continued monitoring of wolves and bears, will enable biologists
and managers to monitor important demographic and genetic population parameters within the ecosystem.
Page 2
Yellowstone Cougar Project
STUDY AREA
This season we sampled cougars in the same area of northern Yellowstone surveyed during the
previous non-invasive study (2004-2005; Sawaya et al. 2011). This area is characterized by steep, rocky
slopes along the Yellowstone River corridor (Fig. 1). Elevations range from 5,300 to 9,500 feet, although most
of the surveys were limited to elevations below 7,200 feet due to snow accumulation and cougar habitat use.
Vegetation consists primarily of grasslands interspersed with patches of Douglas fir (Pseudotsuga menziessi)
and juniper (Juniperus occidentalis). This region experiences cold, dry winters and provides critical winter
range for many of the park’s ungulates, including elk, mule deer (Odocoileus hemionus), and bison (Bison
bison). Cougars compete for ungulates year-round with gray wolves and seasonally with grizzly bears and
black bears . Prominent scavenger species such as coyote (Canis latrans), red fox (Vulpes vulpes), marten
(Martes americana), bald eagle (Haliaeetus leucocephalus), golden eagle (Aquila chrysaetos), raven (Corvus
corax), and black-billed magpie (Pica hudsonia) are found at ungulate carcasses.
Figure 1. Map of survey
routes in the northern portion
of Yellowstone National
Park. Red lines indicate high
priority routes, blue indicate
lower priority routes, yellow
line is current study area
boundary, black lines are
roads, and brown line is the
Park boundary.
Page 3
Yellowstone Cougar Project
N O N I N VA S I V E S A M P L I N G M E T H O D S
We conducted snow-tracking surveys from January through March 2014 along 16 survey routes (10
primary, 6 secondary). The routes were designed to increase the probability of encountering cougar sign
based on long-term knowledge of cougar habitat use, while also allowing
us to maximize travel efficiency and address safety concerns pertaining to
length and terrain of travel. We attempted to walk the 10 primary
survey routes each week, but only surveyed the secondary routes
opportunistically throughout the season. When cougar tracks were
detected, we followed them as long as feasible until discovering hair, scat,
or urine as a potential DNA source. Hair was primarily collected from
bed sites or caught on natural hair snags (e.g., thorns, branches, rocks), while fecal and/or urine samples were
collected at scent-mark scrapes, from cougar latrines at ungulate carcasses, or opportunistically in the snow.
We recorded sign (tracks, scat, visuals, etc.) of bears and wolves along each survey route, and classified the
presence of ungulates (species, group size, age/sex class) observed within 0.5 km of the transect. Presence
and abundance indices for these species will be used to evaluate the potential competitive environment that
cougars face from other large carnivores, as well as the availability of prey within their home ranges. All
data collection was done electronically on Apple® iPad mini tablets loaded with FileMaker® Go database
management software while Garmin® Map62s GPS units tracked our travel. We also used the GPS units to
determine locations of carnivore sign, DNA samples, and ungulate groups.
In addition to our track surveys, we deployed 51 cameras across 27 sites. We used 40 Panthera
Camera Trap V4 cameras set in clusters of 2-4 to obtain multiple camera angles at each site. Additionally,
we deployed 11 Bushnell® remote camera trap video cameras opportunistically along travel routes and at
fresh carcasses and cat scent-mark scrape sites. We maintained 10 camera sites at any given time,
attempting to have one camera station on each primary survey route.
Page 4
Yellowstone Cougar Project
(LEFT) Tail, legs, and paw prints in the snow reveal where a male cougar sat just hours before. (CENTER)
Volunteer technician Kira Quimby collects cougar hairs found snagged on a thorn bush while snow tracking
along a travel route. (RIGHT) Cougars make “scrapes” using their hind feet to make a shallow depression and
deposit urine and/or scat. These scrapes serve as visual and olfactory communication stations.
RESULTS
Snow Tracking
From January 6 to March 29, 2014, we surveyed about 833 miles (1340 kilometers) and 140,000 feet
(42,670 meters) of elevation gain along these designated routes (Fig. 2). During this time, we collected 186
hair samples, 154 of which were natural hair snags (83%) and 32 were from bed sites (17%). We identified
species for each sample through visual inspection of the hair and classification of nearby tracks. In addition
to hair, we collected 7 urine samples and 21 scat samples (Fig. 3). Our average transect length was 13 km,
which took an average of 7 hours. We encountered cougar tracks on 57 of 104 transects (54%) and
collected at least 1 DNA sample on 52 of 104 transects (50%; Fig. 4). The average distance backtracked
from an initial track observation to a DNA sample was 0.3 kilometer, and 69 of 83 backtracks (83%) yielded
at least 1 DNA sample.
Page 5
Yellowstone Cougar Project Figure 2. Map showing each survey transect (in red) for the 2014 winter season Figure 3. Map showing distribution of possible DNA samples from either natural hair snags, bed sites, or from collected scat and urine during the 2014 winter season. Page 6
Yellowstone Cougar Project
Figure 4. Map showing distribution of encountered cat tracks from different age, sex, and family groups of
cougars during the 2014 winter season.
We documented 14 carcasses of
ungulates that were definitely or probably killed
by cougars. Kills were determined by the
presence of cougar tracks, chase tracks with a
blood trail, latrines with cougar scat, and/or
evidence of caching. Cougars cache their kills by
covering them with snow, vegetative debris,
and/or hair pulled from the prey (see photo
right) in an effort to hide carcasses from
scavengers and lessen the effects of freezing or decomposition of the meat. Ten of the carcasses were mule
deer (71%; 4 does, 5 fawns, 1 buck) and 4 were elk (29%; 3 cows, 1 calf). Additionally, we documented
Page 7
Yellowstone Cougar Project
three winter-killed carcasses scavenged by cougars (1 deer fawn, 1 bull elk, 1 cow elk). Most of these
carcass sites provided cougar hair or scat samples.
There were 128 instances of wolf sign (112 unique tracks sets involving 1 wolf, 8 wolf kill sites, 5
scats, and 3 sightings) and 14 instances of bear sign (mostly rub trees until mid-March when bears emerged
from winter dens and we were able to find fresh tracks and beds) along the survey routes. Also, we classified
273 groups of ungulates during February 11 to March 29, counting 2,622 animals from 7 different species
(Table 1).
Table 1. Ungulate groups classified while snow tracking cougars. We only counted
groups visible within 0.5 kilometer of survey routes.
Ungulate species N Total counted Mean group size
Bison 140 1516 10.8
Elk 77 695 9.0
Deer (Mule and Whitetail) 37 288 7.8
Bighorn Sheep 9 78 8.7
Moose 6 10 1.7
Pronghorn 4 35 8.9
Totals 273 2622
Remote Camera Trapping
We placed cameras at 27 different locations from January 7 – March 29, totaling 2,750 camera
trap-nights. These locations produced 66 successful capture events of cougars and produced 144 videos and
234 photos of cougars traveling past, bedding, or scent-marking at a camera station. Additionally, we
identified 22 other species, including grizzly bear, wolf, red fox, coyote, western striped skunk (Spilogale
gracilis), marten, elk, bison, mule deer, whitetail deer (Odocoileus virginanis), bighorn sheep (Ovis canadensis),
moose (Alces americanus), deer mouse (Peromyscus maniculatus), red squirrel (Tamiasciurus hudsonicus), bald
eagle, golden eagle, raven, black-billed magpie, ruffed grouse (Bonasa umbellus), Clark’s nutcracker
(Nucifraga columbiana), Townsend’s solitaire (Myadestes townsendi), and mountain chickadee (Poecile gambeli).
Interestingly, many of the cougar scent-marking scrape sites were frequented by wolves, red fox, coyote,
marten, and western striped skunks - all of which were observed on camera scent marking at these sites.
Page 8
Yellowstone Cougar Project
Four adult cougars (adult females on left, adult males on right) captured from remote camera stations set
along cougar travel routes in YNP.
DISCUSSION
After an 8-year lapse in cougar research, the 2014 field season provided preliminary information on
cougar occupancy and distribution throughout the northern portion of Yellowstone National Park. Since
previous research ceased in 2006, ecological dynamics in this region have transitioned to a system with fewer
wolves, fewer elk, more bison, less deer, and continued prevalence of grizzly and black bears. Although it’s
too early to understand how these changes have impacted cougar ecology, our preliminary findings indicate
that northern Yellowstone still serves as important habitat to a seemingly robust population of resident
cougars and their offspring. Throughout our field season, we documented a wide distribution of age- and
Page 9Yellowstone Cougar Project
sex-specific track measurements, multiple family groups, and photographs and video footage of seemingly
different individuals throughout the study area (Fig. 5). Until genetic results are in and appropriate methods to
estimate population size are used, however, we will refrain from providing approximate numbers of
individuals within the study area during the 2014 winter.
During the summer of 2014, DNA samples will be analyzed at the U.S. Forest Service’s Wildlife
Genetics Laboratory in Missoula, Montana. DNA samples will be amplified and genotyped for species, sex,
and individual identity. Depending on the success rate of our 2014 DNA sampling effort, we will refine our
sampling methods, as well as expand our survey coverage in the coming years. With additional years of
data collection scheduled through 2016, a DNA-based spatial capture-recapture approach will be used to
more precisely estimate cougar abundance throughout the study area.
Previous studies of prey selection by cougars in northern Yellowstone indicated a preference for elk
calves during winter (Ruth et al. in review). This past winter, however, we found selection was greater for mule
deer. Although our sample size was small, this finding may reflect changes in availability and abundance of
prey species. We plan to increase our effort to document predation patterns in the coming years to make
more accurate comparisons with previous cougar research in the area.
FUTURE OBJECTIVES
The current plan is to increase and advance our noninvasive sampling techniques for the next two
winters through continued snow tracking surveys, expansion of survey area coverage, and an increased
camera trapping efforts to aid in demographic monitoring of cougars. Additionally, the team is considering
future plans to capture and GPS-collar individual male and female adults to aid in: 1) quantification of
detection probabilities for capture-mark-recapture estimates; 2) the creation and validation of predation risk
models to locate kills; 3) assessment of changes in predation rates of adults compared to previous estimates;
and 4) compare feasibility and application of noninvasive sampling methods to traditional radio collaring
approaches to evaluate general demographic, behavioral, and ecological questions. Moreover, we plan to
correlate this collar data with the movement and behavioral information from collared wolves, grizzly bears,
Page 10Yellowstone Cougar Project
and elk if sufficient data is available through other research collaborations. Future research goals are
dependent on acquiring additional funding, logistical support, and research permits.
Figure 5. This map shows age/sex class and family group occupancy within the winter 2014 study area
based on documented cougar track measurements and remote camera images. Symbols depict centralized
locations of observations and are not meant to represent home range centers. Size of circles indicates group
size of cats traveling together as indicated by tracks and/or remote images. It is possible that some of the
solitary depictions represent the same individual given observer bias or error in track measurements due to
varying substrates and tracking conditions.
THE YELLOWSTONE COUG AR PROJECT TEAM
The Yellowstone Cougar Project is a collaboration between the National Park Service and several
conservation organizations. Daniel Stahler, Wildlife Biologist in the Yellowstone Center for Resources was the
principal investigator and on-site lead for the study. Toni Ruth, Wildlife Research Scientist with the Selway
Institute, Michael Sawaya, Carnivore Research Ecologist and Co-Founder of Sinopah Wildlife Research
Page 11Yellowstone Cougar Project
Associates, and Howard Quigley, Panthera’s Executive Director of the Jaguar Program and Director of Teton
Cougar Project, were co-principal investigators. The core field technician team was led by Colby Anton and
included Brenna Cassidy and Daniel Perret. Additional personnel assisting with snow tracking surveys included
Nate Bowersock, Brad Bulin, Cheyenne Burnett, Kira Quimby, Colleen Detjens, Caitlin Dodge, John Harmer,
Carolyn Harwood, Felicia King, Matt Metz, Molly Mcdevitt, Michelle Peziol, Claire Qubain, Kole Stewart, and
Kevin Wallen.
Colby Anton will be enrolled as a Dissertation student at the University of California, Santa Cruz
beginning in autumn 2014 to address several of the aforementioned objectives of this study, as well as
develop new questions that broaden our understanding of cougar ecology in this ecosystem. Colby was
awarded the prestigious National Science Foundation's Graduate Research Fellowship for support.
F U N D I N G A N D AC K N O W L E D G E M E N T S
The 2014 field season was made possible through financial support from the National Park Service,
National Park Foundation, and Yellowstone Park Foundation. We would especially like to thank Annie and
Bob Graham and Mr. and Mrs. Peter M. Rapaport for their kind support of this study. Toni Ruth and Mike
Sawaya dedicated time, equipment, and funding. We thank MPG Ranch for supporting the development of
the Filemaker Go carnivore monitoring application. We also thank Yellowstone rangers Brian Helms and Tom
Schwartz for the use of backcountry cabins for safe and efficient field surveys throughout the season. We
thank Panthera’s Mark Elbroch and Howard Quigley and U.C. Santa Cruz’s Chris Wilmers for the loan of
remote cameras. Douglas Smith offered logistical support through the shared use of Yellowstone Wolf Project
resources (e.g. vehicles, equipment, staff, etc.). We also thank Stacy Gunther for her help with the permit
process at Yellowstone National Park. We gratefully acknowledge the support of Yellowstone Center for
Resources’ P. J. White and Dave Hallac. Finally, this field season would not have been successful without the
tremendous effort of our field technicians who traveled many winter miles safely and effectively negotiating
Yellowstone’s cougar country.
Page 12Yellowstone Cougar Project
R E F E R E N C E S (Below are a list of selected references relevant to this current study)
Hornocker, M., and S. Negri (editors). 2010. Cougar ecology and conservation. University of Chicago Press,
Chicago, Illinois, USA.
Murphy, K.M. 1998. The ecology of the cougar (Puma concolor) in the Northern Yellowstone Ecosystem:
interactions with prey, bears, and humans. Ph.D. Dissertation, University of Idaho, 147 pp.
Ruth, T. K., P. C. Buotte, and M. G. Hornocker. In press. Yellowstone cougars: Ecology before and during wolf
reestablishment. University Press of Colorado, Boulder, Colorado.
Ruth, T. K., Mark H. Haroldson, P. C. Buotte, K. M. Murphy, H. B. Quigley, and M. G. Hornocker. 2011. Cougar
survival and source-sink structure on Greater Yellowstone’s Northern Range. Journal of Wildlife
Management 75:1381–1398.
Sawaya, M. A., T. K. Ruth, S. Creel, J. J. Rotella, H. B. Quigley, J. B. Stetz, AND S. T. Kalinowski. 2011.
Evaluation of noninvasive genetic sampling methods for cougars using a radio-collared population in
Yellowstone National Park. Journal of Wildlife Management 75:612–622
Report prepared by Daniel Stahler and Colby Anton. All photographs included in report not from
remote cameras were taken by Daniel Stahler.
Page 13Yellowstone Cougar Project
SELECTED IMAGES FROM REMOTE CAMERAS
This male cougar’s mule deer doe kill yielded cougar
DNA samples as well as video and still images of
feeding behavior and scavenger use by golden
eagles, ravens, magpies, coyotes, and a deer mouse.
Other common scavenger species documented this
winter included red fox and pine marten.
A remote camera set at a cougar scrap site captured video of an adult female (LEFT) vocalizing and scent
marking over the course of several hours, presumably in an attempt to attract a potential mate. The next
morning, an adult male is seen associated with her (RIGHT; note two cougars in this image). Field crews heard
this female vocalizing from across the Yellowstone River during the time the remote camera captured her
behavior.
Page 14Yellowstone Cougar Project
This cougar scrape site drew the attention of
Yellowstone’s two other large carnivores – a curious wolf
and grizzly bear that napped for hours in front of the
camera. These scent-mark stations may serve as
communication areas for information exchange among
carnivores, in addition to their role for communication
among cougars. Future research aims to evaluate the
spatial and temporal interaction of these carnivores on
the landscape.
An adult female with two kittens visited a scrape site and is seen here displaying the lip-curled “flehmen
response” (LEFT) – a behavior performed by a variety of mammals to facilitate transfer of pheromones and
other scents. One of the kittens is seen copying mom (RIGHT) as she freshens the scrape with her own urine.
This form of chemical communication allows cougars to investigate the landscape for relatives, potential mates,
and intra- and interspecific risks in their local home ranges.
Page 15You can also read
