Sun Bear Saga

Marcella is still waiting for Francis to accept her.

It has been several months since our new sun bear male, Francis, arrived on the scene at the San Diego Zoo (see post First Steps for Francis). We had hoped that he would adjust to his new surroundings easily and would become a new mate for our female, Marcella. We had had great success with our previous male, Dibu, who has since gone on to breed naturally with a female at the Columbus Zoo, and our fingers were crossed that Francis could replicate that success. However, our new resident has reminded us that every animal is an individual, each with a particular personality and needs.

For starters, Francis has been more shy and reticent about his time on exhibit. It is common practice that a new animal be given access to the exhibit and behind-the-scenes areas when acclimating them to a new space. The ability to choose where they spend their time helps to mitigate any anxiety caused by the newness of their surroundings and allows them to explore the area at their own pace. However, when given access to his exhibit and bedrooms, Francis always chose to be out of the public eye, remaining in his bedroom. He hasn’t developed a level of comfort with his exhibit that we have seen with our other sun bears.

What’s more, Francis has been less than receptive to the presence of Marcella. Since Francis had gotten along well with at least one other female in his past, we thought he would take to our matriarch. She is, after all, a gentle bear and seasoned in social relationships with males. When she wasn’t rearing cubs, she had been housed each day with Dibu, and they got along just fine. With both bears having a positive social history, our hopes were high. Unfortunately, their social introductions did not live up to our expectations.

On our first attempt, Marcella did her best. She showed interest in Francis with a decided lack of aggression during social encounters through a door. The male, however, was less enthusiastic. Francis escalated the interaction to aggression and made it clear he wasn’t ready to share his space with our resident female. So we backed off.

A few months later, Marcella came into estrus. We decided it was an opportune time to try again. Not only had Francis had plenty of time to become familiar with his surroundings, but the change in our female’s breeding status might entice our male to be more accepting of her. We tried another social introduction across a door, and Marcella had all the right moves. She was clearly near the peak of her estrus, and she backed up to him and took great pains to demonstrate how non-threatening she was. Unfortunately, Francis did not respond in-kind, and he was once again aggressive. The pairing was unsuccessful.

This reminded me of how things used to be with our giant pandas oh-so-many years ago when Shi Shi was our male. Despite panda Bai Yun’s strong, positive behavior, Shi Shi rejected her out-of-hand time and time again. We tried enticing him every way we could: carefully monitored social introductions, pen swaps to increase scent exchange, audio playbacks to heighten his awareness. None of it worked, and any time Bai Yun got close to him, Shi Shi fought her off. In his many years here, he never mated naturally.

We haven’t given up on Francis. He has been placed in an off-exhibit area where he can get a little human social attention, which he is receptive to. He gets lots of enrichment and TLC. And we are swapping scent between Marcella and Francis at least once each week so they can continue to be aware of each other. It is our objective that at some point in the future we will try a social pairing again.

It is critical that we don’t give up. There is no self-sustaining captive population of sun bears anywhere in North America or Asia, and the wild population is on the decline. Since Dibu moved away from San Diego (a good move if one wants to promote increased genetic diversity in the zoo-based bears), no cubs have survived to be added to the captive population in the U.S. We are just going to have to work that much harder to make things happen for Francis and Marcella. It’s important for these two individuals as it is for the species as a whole.

Suzanne Hall is a senior research technician for the San Diego Zoo Institute for Conservation Research. Read her previous post, Bai Yun: Hero Mother.

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