Deer are highly responsive to seasonal changes, with many species participating in regular migrations to optimize survival and access to resources. One of the most well-documented examples is the North American mule deer, which travels vast distances each year. In the warmer months, deer inhabit lush mountain ranges where they can graze on nutrient-rich vegetation. As winter approaches, they descend to lower elevations where the climate is milder, and snow cover is less extreme.

Migration allows deer to balance energy consumption and access to food. The availability of rich summer vegetation enables them to accumulate fat reserves, crucial for surviving the harsh winter. Migration also plays a significant role in the health of the ecosystem, as deer contribute to the dispersal of seeds, promoting plant diversity in their habitats.

In Europe, the red deer is another prominent migratory species, moving between high-altitude summer ranges and lowland winter grounds. However, changes in land use and human development disrupt these traditional routes, forcing deer populations to adapt or face increased mortality risks. In some cases, humans have introduced supplemental feeding programs to help deer survive in regions where migration paths are no longer accessible.

Tracking technology has advanced our understanding of deer migration patterns. GPS collars on mule deer, for instance, have revealed that they remember precise routes and follow them annually, even passing knowledge across generations. This deep-rooted migratory behavior demonstrates their strong connection to seasonal changes and the land.