Best practices for nuisance wildlife control operators in New York State

Home | Wildlife control | NYS DEC | CCE | NYS IPM

Ch 5: Step three: Do it - Lethal techniques

Carbon dioxide chamber - Using a CO₂ chamber, step-by-step

1. Calculate the optimal CO₂ flow for your chamber. This depends on the chamber's size. Your math has to be done in the same units used by the flow regulator. Most are either calibrated in cubic feet/hour or liters/minute. If your flow regulator is calibrated to measure the amount of gas flow in "cubic feet/hour," here's how to convert your measurements to match:
   1. Measure the chamber's size (for this example, say it's 14" × 14" × 34")
   2. Convert this measurement into cubic feet
      first, divide each measurement by 12
      14 ÷ 12 = 1.2
      14 ÷ 12 = 1.2
      34 ÷ 12 = 2.8
      then multiply the three measurements
      1.2 × 1.2 × 2.8 = 4 cu. ft.
   3. Divide the chamber's size (in cubic feet) by the accepted amount of time (5 minutes, or .08 hours) to determine the flow rate: 4 ÷ 0.08 = 50 cu. ft./hour. So in this example, the ideal flow rate for this chamber is 50 cubic feet/hour.
    
2. Place the animal into the chamber. If it's in a trap, you can put the entire trap into the chamber.
    
3. Turn on the carbon dioxide gas until the flow regulator shows the flow rate you've just calculated.
    
4. Watch the animal. At first, the animal may move about or seem excitable. That's a normal reaction that often happens right before the animal loses consciousness. If you see signs of extreme distress (excessive vocalizations, head shaking, fierce sneezing) turn down the flow rate. Later on, when the animal's totally unconscious, it may still continue to move. That's a reflex, not a sign of pain. Some NWCOs find that skunks react better to a slower flow rate.
    
5. Wait a few minutes after the animal's stopped moving and then turn off the gas. You can leave the animal in the chamber a little longer, if you'd like. It's important to confirm that the animal is dead because if it isn't and you expose it to air, it could revive. How can you tell? Touch a long stick to its eyeball. If it's dead, it won't blink. Or hang a string in front of its nose (just keep your hands away from the animal's teeth). If it's dead, the string will stay still, because there won't be any breath to move it.
    
6. If the animal's not dead, or if you're not sure, put it back in the chamber and repeat the process, or use another method.

Next Section (advantages and disadvantages of using a CO₂ chamber)