Terminal dives in mink, muskrat and beaver

Area of Science:

• Wildlife research
• Animal physiology
• Trapping science

Background:

• Leg-hold traps are commonly used for wildlife management.
• Assessing the humaneness of trapping methods is crucial.
• Species-specific physiological responses to trapping may vary.

Purpose of the Study:

• To compare the physiological and behavioral responses of mink, muskrat, and beaver in leg-hold traps.
• To evaluate if trapping methods meet established humaneness criteria for different species.

Main Methods:

• Monitoring of electroencephalogram (EEG), electrocardiogram (EKG), and overt behavior.
• Utilizing an aquatic tank setup for trapped animals.
• Inducing death via CO2 narcosis (submersion asphyxia) for physiological assessment.

Main Results:

• Beaver exhibited CO2 narcosis, while mink experienced "wet" drowning.
• Muskrat showed a mix of drowning and narcosis (approx. 50%).
• Bradycardia was observed in all species, most significantly in beaver. Terminal dive times for mink and muskrat aligned with humane trapping criteria, but beaver did not.

Conclusions:

• Physiological responses to leg-hold trapping differ significantly among mink, muskrat, and beaver.
• Current trapping methods may not be equally humane for all species studied.
• Further refinement of trapping devices is needed to meet humaneness standards across species.