To Smell a Bear

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A physical examination of wild Andean bear named Chris.

Russ is studying wild Andean (or spectacled) bears in Peru and sharing his adventures with us. Read his previous post, 20 Liters Down, 5 Hours to Go.

I’m sometimes jealous of people who can describe how things smell, or taste. I know the same words that they do, but they truly understand how to use the words. If I could, I would describe for you what a wild Andean bear smells like. Instead, all I can say is that “Chris” smelled like a bear.

I’ve been familiar with the general smell of “bear” since I was a child, growing up in black bear country. Since then, I’ve been fortunate enough to smell black bears and brown bears across the mid-western and western United States, but this is the first time I’ve ever sniffed a wild Andean bear. Yep, Chris definitely smells like a bear!

GPS satellite radio collar, ready to be placed on Chris.

“Chris” is what the Spectacled Bear Conservation (SBC) team named this bear, but he would not respond if you were to call his name. Instead, he moves around the landscape in response to cues, signals, and motivations that we don’t yet understand. This morning, he came to the waterhole at 9:05 and turned his back on Javier Vallejos. Javier had been waiting for days for an opportunity like this and darted Chris with an injection of anesthetics. Once Chris was immobilized and his vital signs were stable, we replaced his GPS telemetry collar, gave him a thorough physical examination, and took measurements of his body.

A GPS radio collar is properly fitted to Chris’ neck.

Chris is an adult male bear, in breeding condition and in good physical condition. He’s been photographed on camera traps in the area quite often recently, so there was a good possibility that we could replace his collar, as its batteries were running low. The batteries on these collars last around 12 months, so by replacing his collar now we should be able to collect data on his movements for another year.

When he was darted last year, Chris had large blisters, or sores, on the pads of his feet. Robyn Appleton and her team can only guess that he’d worn down his footpads walking long distances on the rocky trails of the dry forest. This year, his feet are in good condition, which leads us to more questions: why were his feet more worn last year than this year; did he walk more last year than this year? If so, is this because he dispersed from his natal home range last year? Dispersal is the term for the process by which an animal relocates from one living place to another. A natal home range is the area where an animal was born. In most species of mammals, males disperse from their natal home range to a new area at around the time they go through puberty. In a few species of mammals, it is females that disperse, not males. The currently available evidence suggests that female giant pandas disperse but male giant pandas do not; male brown bears and American black bears disperse, but females of these species do not. No one has collected much evidence on whether it is male Andean bears or female Andean bears that disperse, but the probability is that males are the dispersing sex in this species. Were Chris’ blistered feet a clue as to whether male or female Andean bears disperse? Only time, and additional data collection, will answer that question.

We have additional questions on our agenda. We’ve seen and heard several bears in the area exhibiting behaviors that lead us to ask, is this the breeding season for Andean bears in the dry forest? If so, has Chris sired cubs? What determines whether one male sires cubs and another male does not? We can generate hypotheses to address these questions, but it will take a lot more work and data to test the predictions of these hypotheses and reach conclusions about the answers to our questions.

After we finished our physical examination of Chris, we moved him to a comfortable, safe place to recover. The last we saw of him, he climbed up a 10-foot-tall (3 meters) rock face and slowly walks uphill, out of sight into the dry forest. Forty-eight hours later, according to data transmitted by his new GPS collar, he’s 2.72 miles (4.38 kilometers) away, in an area with plenty of sapote trees, which produce fruits that bears in this area often eat. We, on the other hand, have moved less than 100 yards (91 meters), because we’re continuing to try to collar more dry forest bears. I wonder if the next one will smell like Chris?

Russ Van Horn is a senior researcher with the San Diego Zoo’s Institute for Conservation Research. We’ll be posting more about his trip every few days!