Tyler Muhly

PhD Candidate

Faculty of Environmental Design
Professional Faculties Building, Room 1140
University of Calgary

Telephone: 1.403.220. 2475
Facsimile: 1.403.284.4399
Email: tmuhly@ucalgary.ca





I have a B.Sc. in Biology and Environmental Science from Trent University and a Masters of Environmental Design from the University of Calgary. My Masters thesis examined factors contributing to livestock depredation by wolves in southwest Alberta. While completing my Masters degree, I was a Research Associate on a major research project in Yellowstone National Park that examined the ecology of bison movement and distribution in the park. After completing my Master’s degree I worked for two years as an environmental consultant in Alberta. I am currently a PhD candidate in the Faculty of Environmental Design at the University of Calgary where I am researching the influence of humans on wildlife communities in southwest Alberta.

Current Research

In an ecosystem, top trophic level predators interact with the next lower level herbivore, and this interaction influences vegetation -this is an example of a “trophic cascade”. Ecosystems are increasingly “human dominated”, and while the impact of human modification of the earth’s surface on species and ecosystems has been well-studied, the top-down influence of human presence on multiple species and interspecies relationships across trophic levels in terrestrial environments are largely unknown. Trophic cascades provide an important theoretical framework for studying the influence of increasing human activity on species abundance and interactions within ecosystems. I will apply trophic cascade theory to examine the influence of human activity on top predators and the resulting implications for herbivores and vegetation. I will test my hypothesis in the foothills of southwest Alberta (Fig. 1), an ecologically important area that is currently experiencing rapid growth in human density.

Figure 1. Map of the study are in southwest Alberta, Canada. Some wolf pack and elk home ranges are indicated.

I have completed my fieldwork in southwestern Alberta and am beginning analyses. In April 2008, I deployed 40 "camera traps" on trails and roads in the region. These cameras have infrared sensors that when triggered take a picture. These cameras provided thousands of pictures of people and animals that will be used to: (1) measure types and levels of human activity; and, (2) measure density of wildlife. The cameras have provided amazing pictures of wildlife, including wolves, grizzly bears, coyotes, cougars, moose, deer and elk (Fig. 2).

Figure 2. Pictures of wildlife taken in southwestern Alberta using infrared camera traps. Animals captured in pictures include: wolves (a), cougars (b), moose (c), elk (d) - notice the radiocollar, grizzly bears (e), and people (f) – the researcher is pictured.

I also measured herbivory in the study area using "exclosure" cages. These 2 m x 2 m cages prevented herbivores (i.e., cattle, elk, deer, etc.) from grazing within them. Grass within the plot is compared to an open plot outside of the cage to estimate the biomass of grass grazed by herbivores. Pellet counts are also completed at each site to assess relative density of herbivores at the location.

The data collected over the past two years will be used to test hypotheses about the "top-down" effect of humans in southwest Alberta. Specifically, I will examine the effects of various levels and types of human activity on the food chain; from wolves, to elk and cattle, to plants.

My research will provide scientists, industry and managers a better understanding of the ecological consequences of increasing human activity, and thus contribute to enhanced species and ecosystem management and conservation in Alberta, in Canada and in similar terrestrial ecosystems worldwide.


Muhly T, Musiani M, Callaghan, C, Gates CC (2010). Predicting livestock depredation by wolves in southwestern Alberta: implications for wolf management in agricultural areas. In: Musiani M, Boitani L, Paquet P (eds) World of Wolves: new perspectives on ecology, behaviour and policy. University of Calgary Press.

Muhly TB, Alexander M, Boyce MS, Creasey R, Hebblewhite M, Patton D, Pitt JA, Musiani M (2009) Differential risk effects of wolves on wild versus domestic prey have consequences for conservation. Oikos 9999: 1-12. [pdf]

Muhly TB, Musiani M (2009) Livestock depredation by wolves and the ranching economy in the Northwestern US. Ecological Economics 68: 2439-2450. [pdf]

Musiani M, Muhly T, Gates CC, Callaghan, C, Smith M, Tosoni E (2005) Seasonality and reoccurrence of depredation and wolf control in western North America. Wildlife Society Bulletin 33: 876-887. [pdf]

Gates CC, Stelfox BT, Muhly T, Chowns RJ, Hudson (2005) The ecology of bison movement and distribution in and beyond Yellowstone National Park: a critical review with implications for winter use and transboundary population management. University of Calgary Press, Calgary, Alberta. 241 pp.

Musiani M, Muhly T, Callaghan C, Gates CC, Smith M, Stone S, Tosoni E (2004) Recovery, conservation, conflicts and legal status of wolves in western North America. Pages 51-75. In: Fascione N, A. Delach A, Smith M (eds) Predators and People: from conflict to conservation. Island Press, Washington, D.C., USA.

Muhly T, Gates CC, Callaghan C, Mamo C, Alexander S, Tosoni E, Musiani M (2004) Bringing Insight into Livestock Depredation by Wolves in Southwestern Alberta, Canada. Carnivore Damage Prevention News. 7: 10-11.