Arctic Warning Sign: Caribou and the Vanishing Lichen

Migration: Nature’s Long-Distance Strategy

Caribou undertake some of the longest land migrations on Earth .

• Travel thousands of kilometres annually

• Move between summer feeding grounds and winter grazing zones

• Migration ensures access to seasonal resources and reduces overgrazing

If winter feeding grounds degrade, migration alone cannot compensate.

What’s Driving the Decline

Climate Change Effects

• Warmer Arctic temperatures

• Freeze-thaw cycles → formation of ice layers over vegetation

• Shrub expansion replacing lichen-rich tundra

Human Pressures

• Infrastructure development (roads, mining)

• Habitat fragmentation disrupting migration routes

Ecological Impact

• Reduced winter nutrition → lower survival rates

• Declining reproduction

• Potential population crashes over time

Conservation Status

• Listed as Vulnerable on the IUCN Red List

• Some regional populations are already in sharp decline

The lichen issue adds a new layer of risk, because it directly affects survival during the harshest season.

Why This Matters Beyond Caribou

This is a classic example of how climate change disrupts ecological relationships , not just individual species.

• Caribou decline affects predators like wolves

• Impacts indigenous communities relying on them

• Signals broader Arctic ecosystem instability

In ecology, when a species adapted this well starts struggling, it usually means the environment itself is shifting beyond its natural limits.

Exam-Ready Takeaways

• Caribou = Rangifer tarandus

• Only deer species where both sexes grow antlers

• Can see ultraviolet light

• Depend on lichen for winter survival

• Behaviour: Cratering (digging through snow)