Here is a great question sent to me from a wildlife biologist taking my online course, “The Foundations of Wildlife Chemical Capture”. Dr. Mark
Dr. Mark, I just finished Chapter 2 where you discussed the importance of accurate weight estimates to determine safe and effective immobilizing drug doses. I see you mentioned observing the ear size in relation to the body, but what are your other go-to observations for estimating body weight for bears?
Dr. Mark’s reply:
Great question. I have three predominant aspects that I consider when estimating body weight for bears:
- Ears give me a sense of how old the bear is. As bears grow, their head grows but their ears do not. So a big-eared bear is a small younger bear. A bear with little ears (relative to head size) is an older larger bear.
We’re often estimating bear weights when they are in a culvert trap so I first notice if it is a large or small culvert trap because traps vary in size. A small culvert trap will make me think it is a larger bear and can skew my estimate. A larger trap will make a bear look smaller.
My strongest reference is writing down my weight estimates on the drugging field form every time we do a capture. We also document actual weight as well. That way we are learning from every animal. When I have a partner at the capture, I ask them to also write down their weight estimate. After we weigh the bear, we know that whoever is least accurate buys the next coffee.
- Look at the ears
- Look at the culvert size
- Write down both estimated weight and actual weight on the field form so we learn from each animal.