Wild Moose Welfare and Winter Tick Infestation

Winter tick infestations have become a major cause of moose calf mortality and adult welfare harm as climate change extends the tick season in North America.

Key Facts

A single moose can host 30,000 to 90,000 winter ticks in severe infestation years
Tick-caused blood loss and the energy cost of grooming can cause moose to lose up to 30 percent of body weight
Ghost moose with pale hair from excessive rubbing are a visible sign of severe tick burden
Warmer temperatures from climate change extend tick survival and allow populations to reach higher densities
Moose calf survival has declined significantly in areas with high winter tick pressure

Welfare Considerations

Winter tick welfare harm to moose is both individually severe and demographically significant. A moose hosting tens of thousands of bloodfeeding parasites experiences intense pruritus that leads to frantic rubbing that removes protective hair. This hair loss combined with blood loss creates a combined welfare and survival crisis — moose spend so much energy rubbing and lose so much heat through denuded skin that they enter spring in critically poor condition. Climate change is amplifying this ancient parasite-host relationship into an acute welfare and conservation problem.

What You Can Do

Take climate action as the most important intervention for reducing tick pressure on moose
Support research into tick burden management options for moose populations
Donate to moose monitoring programs that track winter tick impacts on population welfare
Learn about the climate-tick-moose relationship as an example of cascading climate welfare consequences