How does climate change affect deer? It's complicated

You may wonder, how climate factors such as temperature, rainfall, snow, and extreme weather events impact wildlife. More specifically, how do our friendly forest rovers, the deer, respond to changes in climate?

Scientists recently conducted a comprehensive study based on 20 years of research on 10 main deer species in boreal and temperate regions: moose, roe deer, wapiti, red deer, sika deer, fallow deer, white-tailed deer, mule deer, caribou, and reindeer.

The team analyzed a whopping 218 articles to draw conclusions on the effects of climate change on the behavior, physiology, and population dynamics of these creatures.

Climate change impacts on deer

The climate, as it turns out, plays a dual role in the lives of deer. While warmer temperatures seem to be beneficial in some ways, they can also tip the scales the other way.

Reduced energy usage and improved food availability during milder winters, initially seem like a great deal for many deer populations. But the catch lies in those species thriving in colder climates like the reindeer or caribou.

Consequences of climate change on deer

Winter temperature variations cause the snow to melt and refreeze, locking food sources under a sheet of ice. Such conditions make it impossible to access lichens, which deer typically feed on.

Likewise, hotter and drier summers might push deer populations’ physiological tolerances to the edge due to heat stress and parasites.

The immediate consequence is a deterioration of the animals’ physical condition. It might also trigger a long-term shift in their distribution, with some species like the moose moving further north.

In comparison to deer species who cope with these issues by seeking cooler habitats and decreasing their daily activities during peak heat hours, moose are considerably more heat sensitive. This results in smaller body mass and ultimately leading to decreased population growth in future generations.

Adapting to climate change

Deer exhibit remarkable adaptability, altering their behavior to mitigate the impacts of changing climates.

In response to fluctuating temperatures, certain species like white-tailed deer adjust their foraging patterns, seeking food sources that provide both nutritional value and a measure of environmental comfort.

During periods of excessive heat, deer are known to restrict their activity to dawn and dusk, thereby minimizing exposure to the harsh midday sun.

Additionally, migratory patterns may undergo transformation, with deer traversing greater distances in search of suitable habitats that offer more temperate conditions.

Evolutionary implications for deer

As climate change continues to accelerate, the evolutionary implications for deer populations are profound and far-reaching.

Genetic diversity plays a critical role in shaping how well these species can adapt over time. Populations with higher genetic variation are more likely to develop beneficial traits that enhance survival in changing environments.

For instance, we might witness a natural selection process favoring deer that are better equipped to cope with heat stress or those that can efficiently exploit new, emerging food sources.

This evolutionary dynamic highlights the challenges posed by climate change, as well as the incredible resilience and potential for adaptation inherent within wildlife species.

Changing migration patterns

Climate change also contributes to altering migration patterns of deer. Spring and autumn temperature hikes reduce snow coverage and depth, inducing deer to migrate earlier in spring and later in autumn.

If this trend continues, species like the caribou and red deer could possibly elimination migration altogether.

Furthermore, the study has identified several avenues for future research, focusing mainly on the potential impact of extreme weather events, snow type, and wetter autumns on deer.

Significance of the study

The findings from National Research Institute for Agriculture, Food and Environment (INRAE) could prove invaluable for wildlife, forest, and park managers to comprehend how deer populations might react to future climate conditions and adapt their population management strategies accordingly to protect these animals.

The interaction between climate change and wildlife is complex and intricate, and understanding it requires patience and dedicated research.

“Climate change causes far-reaching disruption in nature, where tolerance thresholds already have been exceeded for some plants and animals,” noted the researchers.

“In the short term, deer may respond to climate through individual physiological and behavioral responses. Over time, individual responses can aggregate to the population level and ultimately lead to evolutionary adaptations.”

The study is published in the journal Global Change Biology.

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