Bear Courtship

This camera-trap photo shows a male Andean bear, left, being rebuffed by a female Andean bear.

This camera-trap photo shows a male Andean bear, left, being rebuffed by a female Andean bear.

To improve giant panda captive breeding programs, researchers have carried out numerous investigations of how male and female giant pandas communicate with each other, and how their hormone profiles change independently, and in response to each other. Applying this knowledge has contributed to the success of giant panda captive breeding efforts, which are now based on more information than is available for any of the other bear species.

In the dry forest of northwest Peru, where we’ve been working with the Spectacled Bear Conservation Society, there appear to be some relatively predictable cycles. Food for the Andean (spectacled) bears appears to be scarce for most of the year, so some of them turn to eating pasallo trees, and all of them gradually lose weight. Then, when the fruit of the sapote is available, the bears focus on that fruit and gain weight. We’ve suspected that the bears mate during that same season.

Although there isn’t much information on what courtship looks like among wild Andean bears, we suspect that males crisscross the landscape, looking for females that are in estrus and so may be willing to mate, or which will be ready to mate in the near future. Once a male locates a female, probably through some sort of olfactory communication that is similar to but different from the means used by giant pandas and polar bears, we think a male will then follow that female, trying to determine when it’s safest to approach her, while chasing off any other males that might also try to mate with her.

Like all bears, Andean bears are not social as adults, but obviously a male and female have to respond positively toward each other in order to mate. We believe that in Andean bears, like giant pandas, the coordination of reproductive readiness (and willingness!) is influenced by hormones, chemical cues, and behavioral interactions. A male has to get the timing right. If he approaches the female at the wrong time, she’s likely to vocalize loudly at him, box his ears, run away, or any combination of those alternatives. We’ve recently retrieved photos from a camera trap in the dry forest that suggests that one male, at least, didn’t quite time his approach correctly!

Russ Van Horn is a scientist with the San Diego Zoo Institute for Conservation Research. Read his previous post, Bear Ambassador Learns Importance of Plants.