The Greater Yellowstone Area Mountain Ungulate Project

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Telemetry Studies

GPS-VHF Telemetry Studies of Mountain Ungulates in the Greater Yellowstone Area

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To enhance the understanding of bighorn sheep and mountain goat ecology in the greater Yellowstone area (GYA), the Mountain Ungulate Project initiated by Montana State University has, through strong collaboration among many agencies, initiated extensive GPS and VHF radio telemetry studies. This large-scale study, covering ten study areas across the GYA, will provide a broad array of ecological information critical to managing and conserving these ungulate populations. This research aims to obtain information on the following:

1) Population dynamics and vital rates (survival & reproduction), including the factors that influence annual variation in demographic performance,
2) Spatial ecology, including seasonal distribution patterns, movement dynamics, and the potential for genetic exchange and disease transmission,
3) The effects of climate warming on these two alpine and subalpine species, &
4) The competition dynamics as a result of continued expansion of the non-native mountain goats on bighorn sheep ranges.

In order to collect this information, we have designed and begun to implement GPS and VHF telemetry studies. These studies incorporate a dual collaring and multiple deployment strategy for ten study sites representing various environmental and ecological attributes.

The dual collaring strategy involves the deployment of both a GPS and VHF radio collar on a single individual. Adult bighorn sheep ewes and adult mountain goats will be equipped with the two collars. The GPS collar uses store-on-board data collection and archiving technology and is scheduled to drop off after two years. The VHF collar, which will remain on the animal for life, will be in a semi-dormant state for the first two years during which the GPS unit is archiving data and sending signals from its own VHF beacon; the VHF collar will then switch to its programmed working duty cycle (after the GPS collar has dropped off the animal) at the start of year three and is expected to transmit for an additional 4 years before its battery is depleted.

When the GPS collar has been recovered and the data downloaded, it will be reprogrammed and redeployed on another animal (preferably females of both species), either of the same or different herd depending on the herd size and circumstances. For this second deployment, we will use the same tactic as the first; two years of spatial data collection by the GPS collar, followed by four years of transmission from a new VHF collar. After the GPS collar drops two years later, it will then be redeployed a third time with a new VHF collar on a male or female either in the same or different herd depending on the size of the herd and/or priorities of the administrating management agency. Thus, we will efficiently combine GPS spatial studies and VHF demographic studies into a long-term telemetry project.


Gaining these additional years of data collection by using this strategy will increase the number of animals sampled, allowing us to obtain considerable spatial and demographic detail, as well as to gain insight on potential annual variation in movement patterns due to variation in plant phenology and snowpack dynamics caused by annual variation in weather.

Download full PDF at top of page to read more about the telemetry studies, including:
-capture and collaring techniques
-health and disease sampling
-field studies for population dynamics and
-database overview


written by Jesse DeVoe


Other Science:

Occupancy Studies >

Population Trends >

Age Ratio Dynamics >

Integrated Databases >

Telemetry study sites across the GYA
Green = Study in progress
Orange = Study in the works
Purple = Potential study site

1) Gros Ventre, WY
2) Palisades, ID
3) Upper Yellowstone River, MT
4) Pilot-Cache, WY
5) Sunlight Basin, WY
6) Line Creek, MT
7) Mt. Everts, WY
8)Grand Teton National Park, WY
9) Taylor Hilgard, MT
10) Spanish Peaks, MT


Study sites superimposed on locations of bighorn sheep (blue) and mountain goats (red)

CLICK HERE for capture and instrumentation details




VHF and GPS collar combination for dual deployment on mountain goats (left) and bighorn sheep (right). To reduce visual impact, belting colors are intended to match the pelage of the collared animal.

VHF collars--> Telonics MOD-401 MK9
GPS collars--> Telonics TGW-4400 GEN 4