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The Impacts of Urbanization on Mule Deer in British Columbia

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Introduction

Mule Deer (Odocoileus hemionus) in British Columbia Canada

Mule Deer (Odocoileus hemionus), a native species to North America, have experienced high population growth rates across British Columbia. Due to this growth, the impacts of urbanization on Mule Deer have become increasingly important areas of research [1]. Mule Deer are an Indigenous species to the territory covering the West Coast down to the Great Plains of North America [2]. Mule Deer are known to inhabit regions in British Columbia with rugged topography containing areas of vegetation and are noted as a vital food source and economic asset to Indigenous people in British Columbia [2]. Mule Deer require shelter and food, primarily consisting of foraged shrubs and plant debris, which is seen to be negatively impacted from causes such as deforestation and the growing development of urban centres [3]. Expanding urban development is negatively impacting non-urban deer populations by causing habitat fragmentation leading to the reduction of available vegetation and forest canopy cover, which is especially important for populations residing in regions with high snowfall. Light pollution that is produced from increasingly prevalent urban centres is also acknowledged as impacting Mule Deer's foraging patterns despite plentiful vegetation being available [3]. Therefore, as urbanization grows across British Columbia, Mule Deer are being negatively impacted by extreme habitat fragmentation, light and natural resource pollution, and food scarcity driven by urban development and land use change.

Habitat of the Mule Deer

Mule Deer live in a variety of habitats across British Columbia and are a native species to the North American region [2]. In general, vegetation conditions have degraded over time due to increased human activity influencing vegetation distribution, quality, vertical and horizontal density, and proximity to water and security cover, all of which are required for the maintenance of mule deer populations in a given region. Mule Deer also have seasonal habitat needs. If an area meets all their annual needs, then the population will remain, however, most often, Mule Deer will migrate between different habitat areas to meet their seasonal needs. The main reason that drives the need for Mule Deer to seasonally migrate is so that they can seek out thermal cover in the winter, primarily in areas that experience heavy snow fall. Security cover is an important feature that Mule Deer rely on their habitats to provide. Coniferous forest are utilized for their higher snowfall protection and thermal cover whereas deciduous forest provides increased foraging shrubs and debris. Vegetation and landscape features can also be utilized to allow Mule Deer to hide from predators for survival purposes [1]. Overall, habitats play many crucial roles in the location, survival, and health of Mule Deer populations across British Columbia.

Impacts of Urbanization on Mule Deer Habitat

Habitat Fragmentation

Mule Deer (Odocoileus Hemionus) crossing a road

The habitat fragmentation caused by urbanization has profound impacts. Researchers have found that there are genetic impacts on Mule Deer subpopulations corresponding to urban infrastructure that reduces habitat connectivity separating sub-populations from one another and decreasing genetic variability within sub-populations [4]. It is evident that increased connectivity of habitats, either through highway corridors and safe crossings or decreased road density, results in an increased habitat range reflected by sub-populations passing genes between sub-populations. Ungulates, like Mule Deer, require a large area to roam as well as abundant forage and shrubs that are utilized for nutrient intake [4]. Due to these survival needs, food scarcity and habitat fragmentation are seen to be a major threat to the species. Habitat fragmentation can also result in increased energetic costs for Mule Deer [1]. This is because urban development often results in the reduction or complete loss of forest cover which forces Mule Deer populations to travel farther distances in order to fulfill their seasonal needs and receive adequate winter protection. These increased energetic costs can take a harsh toll on the species and lead to dwindling Mule Deer populations [1].

Food Scarcity

Mule Deer utilize location for forage more intensely when water and security cover are present. Urbanization poses a threat to these ideal forage areas since human impacts often result in ecosystems that are unable to support the vegetation needed for security cover, thus increasing food scarcity by decreasing the number of ideal forage areas [5]. The ideal forage for Mule Deer are shrubs, however, with increasing logging and subsequent habitat fragmentation, areas with sufficient shrubbery are increasingly scarce especially in the winter. Mule Deer have a multitude of stand needs in forage areas to ensure energetic costs do not become too high and adequate security is present. Without forage areas with these qualities the energetic cost of travel and maintaining body temperature during the winter become very high and food to meet this increased energetic demand is scarce [3].  Despite an increased prevalence of shrubbery in clearcut areas, Mule Deer heavily avoid these areas since they on average have much deeper snow than coniferous and deciduous forest areas. Mule Deer have been observed to select deciduous forest areas for forage likely due to increased shrubbery, even though there is reduced snow inception and thermal cover in comparison to coniferous forest areas which are often associated with less shrubbery but higher snow inception and thermal cover [6]. Generally, research has observed that open deciduous forest areas are also important to winter forage due to snow depth being one of the most important factors to consider in the management of food scarcity for mule deer.

Pollution

Urbanization commonly results in artificial light pollution; researchers have found that mule deer are much less likely to utilize locations for forage when high levels of artificial light are present, even if these locations have a high vegetation density [7]. Artificial light is also observed to shorten the time Mule Deer spend at forage areas showing that Mule Deer generally prefer to graze in areas with natural light sources due to their need for security cover from predators. Mule Deer are also more likely to cross roads and pass through corridors when there are less sources of artificial light. Generally, it is important to consider the impacts of artificial light pollution on the use of forage areas and the likelihood of Mule Deer crossing roads in comparison to safe corridors [7]. Pollution of water sources is also a threat to the Mule Deer. This species aims to balance energetic costs with meeting essential needs such as drinking water. If the nearest water source is polluted or if the most suitable habitat has a polluted water source it will still most likely be used. Due to polluted water sources, Mule Deer often have to travel long or steep distances to reach clean water sources which increases their energetic costs, evidently threatening the health of Mule Deer populations [7].

Impacts of Urbanization on Mule Deer Behaviour

Migration

Urban Mule Deer that have become comfortable around human behaviour tend to cross roadways more willingly when migrating resulting in increased experiences with human conflict in comparison to non-urban Mule Deer[1]. Additionally, due to urban Mule Deer's comfort level in urban settings, they tend to migrate from town to town rather than seeking out natural habitats for winter forage [1]. Though human effort has been put in to create overpasses to aid in wildlife movement and migration, Mule Deer have been found to avoid overpasses close to areas were human impact has increased[8].Generally, urban Mule Deer experience higher levels of human conflict and incur higher energetic costs when forced to migrate due to their desensitization to urban settings.

Predation

It is especially evident through translocation efforts in BC, that urban Mule Deer experience higher level of predation than non-urban Mule Deer [1]. This susceptibility to predation is attributed to human desensitization. Urban Mule Deer do not associate humans with danger like non-urban Mule Deer and, therefore, are more likely to be killed by hunters and be hit by vehicles while crossing highways [1]. Furthermore, translocation studies have found that urban Mule Deer being unfamiliar with natural habitats reduces their evasion ability when being hunted, subsequently experiencing lower survival rates in comparison to non-urban Mule Deer [1].

Current Conservation Efforts

Population Monitoring - Surveys & Modelling

One of the primary conservation efforts for the Mule Deer in British Columbia is the monitoring of Mule Deer population sizes. The estimation of population sizes informs wildlife agencies on how they can adjust the availability of hunting permits appropriately to meet post-hunting season population targets [9]. These targets can vary; most often, it is a post-hunt population size or density or even an adult sex ratio that would ensure the conservation of Mule Deer populations [9]. A variety of techniques can be used for population estimates. Hunter harvest surveys are used to capture the sex and age composition of the total harvested Mule Deer in a given season[9]. Mule Deer surveys, such as ground counts or aerial counts, are used in the spring and autumn to capture general abundance or density [9]. Given the information gathered regarding abundance, density and composition, population models can be applied to better understand the likely population sizes and inform decisions about the next hunting season [9].

Population Monitoring - Collar Tracking

For more extensive information on Mule Deer populations, satellite collars are often utilized. Collared deer can be tracked generating data on the spatial distribution of Mule Deer populations [10]. This also allows wildlife agencies to understand survival rates and estimate the range of Mule deer populations [10]. The acquisition of this data informs stakeholders of the efficacy of current management actions, the accuracy of population models used in estimation and migratory patterns of Mule Deer in BC [10]. Radio collar tracking has been used in eastern Oregon, USA to assess Mule Deer survival rates through different periods of migration which found lower survival rates during fall migration[11].

Population Monitoring - Health Assessments

While health assessments of Mule Deer in BC are not frequent, they are performed occasionally to determine the health impacts and efficacy of other ongoing conservation efforts such as translocation. Health assessments for Mule Deer consist of taking blood samples from a variety of individuals in a Mule Deer population to determine the prevalence of disease and pregnancy rates[12]. Health assessments aid wildlife agencies in determining how effective translocation efforts have been and capture the overall prevalence of disease in an area[12]. Since translocation poses the potential risk of disease spread between Mule Deer populations, health assessments are important to mitigate this risk[12]. This conservation technique, along with translocation efforts, can work together to contribute to the successful and safe relocation of Mule Deer in urban regions to non-urban regions, without the risk of harm to either the population being translocated or the pre-established populations.

Translocation

To address the negative impacts of urbanization on Mule Deer in BC, wildlife agencies have also used translocation which involves moving Mule Deer away from urban settings[1]. However, Mule Deer that are familiar with urban settings have been observed to no longer associate humans with danger[1]. Consequently, when Mule deer are translocated from urban settings, they are more likely to be killed by hunters than non-urban Mule Deer, as they are desensitized to human presence[1]. Unfamiliarity with release sites can also impact the survival of translocated urban Mule Deer as they tend to travel greater distances after compared to non-urban Mule Deer This is likely because of their willingness to cross roadways and their tendency to return to nearby municipalities[1]. Although translocation poses many challenges affecting the survival rate of urban Mule Deer, it can be a promising conservation strategy for young deer who are not yet entirely desensitized to human presence[1].

Wildlife Passages

Wildlife agencies in BC are attempting to address the impacts of urbanization on Mule Deer habitats through the construction of safe wildlife passages across highways to connect large areas of habitat[13]. This management action address both the loss of habitat connectivity and high mortality of Mule Deer from vehicle collisions. In addition, safeguarding measures like fencing are being constructed to further reduce access wildlife have to crossing highways[13]. This conservation effort has reduced wildlife-vehicle collisions by over 80% in some areas of BC, Mule Deer being one of the most frequent species captured on trail cameras in the underpasses[13]. This type of intervention is especially beneficial for Mule Deer seeing as they tend to cross highways most frequently due to their need to migrate long distances for sufficient winter and summer forage[5]. Overall, implementing safe wildlife passages around high-traffic crossing areas is a simple and effective method to address the impacts of urbanization on Mule Deer [13]. Seeing as habitat fragmentation is one of the most significant impacts of urbanization on Mule Deer as well as how the desensitization of Mule Deer to human activity has led to increased crossing of roadways this conservation effort is multifaceted in it's approach addressing multiple issues simultaneously[13]. Additionally, there are mutual benefits derived from having fewer Deer crossing highways since drivers will have fewer dangerous encounters with Deer on the road.

Conflict Reduction & Population Reduction of Urban Mule Deer

The province of BC has invested in implementing conflict reduction strategies to reduce the number of Mule Deer in urban settings[14]. Conflict reduction strategies include the use of deer repellents in urban areas, deer-resistant landscaping such as additional fencing or deer-resistant planting to reduce the attractiveness of local greenery[14]. Also, constructing signage which informs drivers of the frequent presence of Mule Deer populations in certain areas to reduce collisions[14]. These strategies aim to reduce the number of Mule Deer present in urban areas thus reducing the number of Mule Deer that become desensitized to human activity and incurring the negative impacts of urbanization on Mule Deer behaviour. The province of BC also authorizes lethal culls to reduce the populations of urban Mule Deer, this strategy ultimately aims to reduce human conflict with Mule Deer which are significantly desensitized to urban settings[14]. Overall, conflict reduction and population reduction strategies aim to reduce the number of Urban Mule Deer without investing in strategies to improve natural habitats for Mule Deer to occupy.

Looking Forward

Indigenous Land Management Practices

Mule Deer (Odocoileus hemionus) fawn and doe

Indigenous communities need to be included beyond field-level management in order to provide ecological knowledge that is rooted in centuries of intergenerational wisdom if we want to work towards improving the climate resiliency and long-term preservation of native species and land[2]. Looking towards the future, efforts must be put towards Indigenous sovereignty through the use of collaborative governance in order to honour both Indigenous ideas and ecological practices as well as to work towards decreasing the negative environmental impacts on the Mule Deer population in British Columbia that arise from the growth of urban centres [2]. It has been acknowledged that more robust policies and legislation need to be developed in order to ensure equally weighted and regulated conservation management efforts between Indigenous communities and the Provincial Government[2].

Protecting Habitats

One of the more prominent solutions would be to avoid disrupting corridors and terrain that are used by mule deer to access foraging areas when developing infrastructure [1]. Habitat fragmentation majorly impacts non-urban Mule Deer's ability to forage and find adequate shelter, especially for populations that reside in areas with harsh winter conditions. Aside from just limiting habitat disruption, it is also important to manage and offset the impacts that do occur through rehabilitation efforts and protected areas. An example of protected area use in British Columbia comes from members of the St'át'imc territory who have proposed the idea of implementing protected areas that focus specifically on Mule Deer fawning zones [2]. This would focus on supporting the Mule Deer species while also engaging with Indigenous communities in British Columbia to implement conservation practices.

Water availability

Water development entails human creation of additional water sources for mule deer populations in areas where water scarcity is an issue or during summer months when it becomes an issue, however this must be done carefully to avoid providing contaminated water[1]. Additionally, improving the forage available for Mule Deer near naturally occurring water sources aids in lowering the energetic costs while resolving water availability issues simultaneously[1]. Improving available forage is a more natural approach that enables Mule Deer populations to reestablish long term residency in habitats that have adequate foraging ground and natural fresh water sources.

Habitat Evaluation

Habitat evaluation and monitoring overall is one of the best investments in determining and responding to the impacts of urbanization on mule deer populations, when the issues are identified the path forward is much clearer[1]. This approach aims to identify which key components of a Mule Deer habitat are missing to efficiently improve the habitat to an ideal state[1]. Consequently, this approach reduces stress on Mule Deer populations by aiming to increase the abundance of ideal habitat areas[1]. Another management strategy includes the translocation of urban deer to non-urban regions[1]. Habitat evaluation is a crucial component to the success of this conservation management strategy because the region in which the urban deer are translocated to is dependent on pre-existing non-urban deer populations. To ensure no diseases are spread from the urban population to the non-urban population, habitat location is required to be assessed before the translocation of urban Mule Deer can occur[1].

Conclusion

As urbanization is increasing in BC, the impacts we are seeing on Mule Deer are also increasing. Human impact on vegetation is leading to habitat loss and fragmentation, food insecurity, and increased pollution. Habitat fragmentation in combination with logging has created greater food scarcity for the Mule Deer population, who primarily rely on shrubs. Light pollution, produced from urban centres, and water pollution are also issues the Mule Deer in British Columbia are currently facing. Mitigation efforts such as adopting Indigenous Land practice conservation techniques, habitat protection, increasing water availability, and habitat evaluations are all crucial steps in supporting the health and well being of the Mule Deer species. Overall, continued monitoring of the Mule Deer's is necessary to better understand and mitigate the ways in which they are impacted by growing Urbanization across British Columbia.

References

Male Mule Deer (Odocoileus hemionus) foraging
  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 Wright, C. A., Adams, I. T., Stent, P., & Ford, A. T. (2020). Comparing Survival and Movements of Non-Urban and Urban Translocated Mule Deer. The Journal of Wildlife Management. 84(8), 1457–1472.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Andrascik, N., & Grenz, J. (2025). Reconciling wildlife governance in a changing climate: A systematic review of mule deer management in St’át’imc Territory. Environmental Science & Policy, 171, 104136.
  3. ↑ 3.0 3.1 3.2 Armleder, H. M., & Dawson, R. J. (February 1992).  Logging on mule deer winter range: An integrated management approach. The Forestry Chronicle. 68.
  4. ↑ 4.0 4.1 Ditmer, M. A., Carter, N. H., Hersey, K. R., Leclerc, M., Wittemyer, G., Stoner, D. C. (2023). Navigating the wildland-urban interface: Sensory pollution and infrastructure effects on mule deer behavior and connectivity. Basic and Applied Ecology. 73, 62-71.
  5. ↑ 5.0 5.1 Arnett, E. B., Belinda, S. R., Gray, S. S., Ielmini, M., Logan, B., Pieron, M., Tator, I. (2023).  Threats to Habitat Function. In Ecology and Management of Black-Tailed and Mule Deer of North America.  Boca Raton.
  6. ↑ Serrouya, R., & D’Eon, R. G. (2008).The influence of forest cover on mule deer habitat selection, diet, and nutrition during winter in a deep-snow ecosystem. Forest Ecology and Management. 256(3), 452–461.  
  7. ↑ 7.0 7.1 7.2 Ditmer, M. A., Carter, N. H., Hersey, K. R., Leclerc, M., Wittemyer, G., Stoner, D. C. (2023). Navigating the wildland-urban interface: Sensory pollution and infrastructure effects on mule deer behavior and connectivity. Basic and Applied Ecology. 73, 62-71.
  8. ↑ Hamilton, Kaela M.; Bommarito, Thomas; Lewis, Jesse S. (February 2024). "Human activities influence mule deer use of overpasses across multiple scales". The Journal of Wildlife Management.
  9. ↑ 9.0 9.1 9.2 9.3 9.4 Hatter, I. W., Dielman, P., & Kuzyk, G. W. (2017). An integrated modeling approach for assessing management objectives for mule deer in central British Columbia. Wildlife Society Bulletin. 41(3), 508–515.
  10. ↑ 10.0 10.1 10.2 Procter, C., Iredale, F., Jury, D., Manual, M., Council, L., & Lillooet, B. C. (2014). Mule Deer Buck Migrations and Habitat Use in the Bridge River, British Columbia.
  11. ↑ Schuyler, Elizabeth M.; Dugger, Katie M.; Jackson, Dewaine H. (August 2018). "Effects of distribution, behavior, and climate on mule deer survival". The Journal Of Wildlife Management.
  12. ↑ 12.0 12.1 12.2 Mathieu, A; Flint, M; Stent, P; Schwantje, M; Wittum, E (2018). "Comparative health assessment of urban and non-urban free-ranging mule deer (Odocoileus hemionus) in southeastern British Columbia, Canada". ProQuest. PeerJ.
  13. ↑ 13.0 13.1 13.2 13.3 13.4 Chow, E; Lamb, C (2023). "Safe Passages for Wildlife in the Southern Canadian Rockies" (PDF). Fish and Wildlife Compensation Program. BC Government.
  14. ↑ 14.0 14.1 14.2 14.3 BC Government (2016). "FACTSHEET: Urban Deer Management in B.C." BC Gov News. Retrieved April 12, 2026.


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