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A Tale of Three Bintlets

It’s been a little while since we discussed the Zoo’s baby binturongs, or bintlets if you prefer. A lot has happened with these guys over the past few weeks, but I guess I will start at the beginning to make sure everyone is on the same page. Starting in early 2023, we started to see breeding behaviors between the Zoo’s two binturongs, Baloo and Bramble. This was great, because we brought them together here at the Zoo specifically for breeding. You would be surprised how often that doesn’t work out though. Everything appeared to go great, and we had high hopes of possible binturong babies in the spring. When April rolled around and we didn’t see anything, we started having doubts. These doubts were made fact when we started seeing breeding behaviors once again. Now, all the expectations shifted to early summer. We were ready when early summer came along, but again, nothing. We did not see strong breeding behaviors between the two of them at this time, so our expectations were not very high heading into the fall. As they say though, “expect the unexpected.” In early August, we noticed that Bramble had put on some weight, and she was a bit more hungry than normal. We decided to play it safe and get an ultrasound image on her just so we could rule out the possibility of her being pregnant. Through the hard work of the Zoo’s Carnivore keepers and Vet staff, we were able to conduct a voluntary ultrasound, which showed that she was indeed pregnant with at least two fetuses. We conducted multiple ultrasounds throughout the month, which all showed two fetuses. The vets always inserted the caveat that one might be hiding, but they could only see two. 

At this point all preparations ramped up to make sure we were ready by the end of August. We installed the nest boxes and cameras, procured a lot of bedding materials for the boxes as well as the floors, and dusted off and updated the birth plan that was written earlier in the year. Many people ask just how we know what will happen during these births. This is a great question. Here at the Zoo, we’ve never had baby binturongs, but we all kind of knew what to expect. Believe it or not, binturongs, along with many other zoo animals, come with a manual. These Animal Care Manuals are developed through the collaboration of many different very experienced members of the Association of Zoos and Aquariums (AZA). They discuss subjects such as nutrition, veterinary care, habitat construction, transport, temperature constraints, reproduction, and many others. While not every question can be answered using these, they are a very important guidebook when working with these animals. In this manual, as well as from conversations we had with other institutions, it was determined that although binturong mothers could have 1-5 bintlets at a time, they typically could or would only raise two successfully. Because of this, many zoos will need to pull one of the bintlets for hand rearing. The problem with hand rearing is that these animals typically become imprinted on humans and have a rough time integrating back into the animal population. We kept this section included in our birth plan, but we didn’t think we would end up needing it.

As time went by and we entered Bramble’s birthing window, we were all on high alert looking for any changes in her behavior. You just never know what to expect with a first-time mom. On the morning of August 31st, the keepers reported that she did not consume her diet from the previous night and was not interested in her morning food either. This just so happened to be one of the signs we were looking for, so we knew we were close. We then noticed that she was entering active labor.  The manual stated that binturongs typically have their babies overnight, so even though we were ready, we had some time. Bramble decided not to wait until the evening, however- she decided that a good time was right around lunch. The first bintlet arrived and all was well. We just had to wait a little while for the second one to arrive, and we should be done for the day. After some more intense labor, the second one came and once again, all was well. Bramble was being a good mom by cleaning all of her babies up, but we had not seen any nursing yet.

We all started celebrating after the birth of the second bintlet, until a text came from one of the keepers watching them, that a third bintlet was confirmed to have been born as well. Although unexpected, we were ready to jump into action due to our birth plan. We decided to give it a little time to see just how things went before we just went in and removed anyone. While Bramble had cleaned up her babies well and was not showing any aggression towards them, she was not nursing any of them. She had had a long hard labor, and she looked very tired and uncomfortable. After about an hour or so, she had walked away from her babies and was resting on the other side of her den. While the babies could go a little while without food, they can chill very easily, which is very dangerous. Through discussions between the Carnivore and Vet teams, the decision was made to pull all three bintlets, two boys and a girl, for hand rearing, as Bramble had lost all interest in them.  This was not a decision that we wanted to make, but we felt it was necessary. 

It’s a good thing we had everything ready, even though we didn’t think we would need it. We set up a schedule for feedings every two hours.  Those 2am and 4am feedings are fun, let me tell you. After that first night, all three bintlets had eaten multiple times and were nice and warm. We did not want to completely give up on Bramble, as she was showing some good motherly instincts prior to her walking away. We hoped that she had just needed a good night’s sleep. We decided to place one of the bintlets (boy) back with her to gauge her reaction.  Upon hearing her baby make some noise, Bramble perked right up and became very interested. One of the keepers entered the den and literally handed the baby to Bramble, who accepted it immediately. She grabbed it by the scruff and took it immediately into the nest box where she started to nurse this baby. Since she was so good with this baby, how would she do with two? We decided to try to introduce a second bintlet back to mom. Getting the second bintlet, girl, back with mom followed the same procedure as the first one. Bramble accepted it immediately and hauled it back to the nest box. Within an hour or so, we observed both bintlets nursing. That was a great relief for all of us. 

We still had #3 though. He had not gained nearly as much weigh overnight as his siblings, which is why he was not selected for reintroduction. We decided to not push our luck, but instead to go with what our birth plan had laid out. We set in for the long haul with feedings every two hours, 24 hours a day, 7 days a week. The little guy, along with his caretakers, had to take a few days to figure each other out, but once that occurred, he began to thrive. While we all loved taking care of him, we knew the best thing for him was to get him back with his mom and siblings as soon as possible. Through all of our research, we located other institutions that had hand reared a third bintlet and had tried to reintroduce, some with good results, some with bad. We had multiple conversations with these other institutions in order to pick their brains for everything they knew about binturong babies and introductions. As it just so happens, Bramble came from a litter of three girls, where one was hand reared and reintroduced successfully between 4-6 weeks of age. This would be the model we would, most likely, copy.     

As time went by, Bramble and the two bintlets were still doing great and baby #3 was still thriving in our care. Since everyone was doing so well, we thought about accelerating our 4-6 week schedule a bit. This had never been done, so far as we know, so we didn’t know exactly how it would turn out, but we felt we had to try. At three weeks old, with a full belly, we reintroduced #3 back to the family. #3 was a bit behind in weight, but we were hoping he would catch up soon. Our biggest questions were, would mom accept him after so long, whether or not he would figure out how to nurse, and if his larger siblings would actually let him do it. We did see that #3 was initially nervous to be around all of these strange creatures. This emphasized the need to introduce him earlier than expected. We wanted him to grow up as a binturong, and he needed to be with his family.

We, unfortunately, did not see any nursing from #3 that first day. We did not want to remove #3 from the family to “assist” him with supportive care, so we tried out the idea of simply giving him supplemental feedings throughout the day in with the family. Bramble was very hesitant to shift away from the bintlets, but due to the relationship the keepers had built with her, we were able to enter the den and give #3 a bottle as she looked on. This was the routine for a few days, until Bramble felt comfortable enough to shift away from the babies for a while as she ate her meals. We were then able to easily gain access to all the babies to get weights and offer #3 his twice daily bottles. After several days, and a lot of effort from #3, he was seen successfully nursing from Bramble. He was not, however, getting enough milk from her, so we kept up the twice daily supplemental feedings. As time went by, #3 was getting more and more comfortable with his family, and we began to see many play bouts between him and his siblings. He was always ready for his bottles when they arrived though. He was starting to catch up in size to his siblings, but he had some more work to do.

Through all of this time, all of the bintlets had spent a majority of their time in the nest box. One would occasionally wander out the door, only to be hauled back in by mom. #3 and his sister were the first ones to really leave the nest box and start exploring their new, expanded world. Both were still a bit wobbly, but they made their way through all the platforms and perching well enough. The other male was not so keen on leaving the confines of the box, but #3 was fearless. Bramble would try to get them back in the box, with limited success. 

At five weeks of age,  Bramble had no hope of containing any of the bintlets in the nest box. They were all out of the nest box most of the time and were exploring every square inch of their dens from the floor to the ceiling. It is amazing at what a difference a week makes, as all three had become very agile and good climbers. Having that prehensile tail to help stabilize things definitely helps. At this point, #3 was really starting to catch up to his siblings in weight and size but would still readily come over for his twice daily bottle. We noticed that he and his siblings were also becoming a bit more interested in tasting some of Bramble’s food as well. This was completely expected. We just didn’t know exactly when it would happen.

At six weeks of age, we started offering the bintlets their own portion of Bramble’s daily diet consisting of fruits and other items. We had to cut it small to make sure nobody choked. All three bintlets readily took to these new diet items, and it is quite the feeding frenzy when they are offered. Because of this new food, #3 actually started to not finish all of his bottle feeds, and refused some all together.  

As of today, #3 is not the smallest of the group anymore (they are all within ~100g or 3oz of each other), and he is only being offered a bottle once a day, even though he sometimes does not want it. It is only a matter of time before that last bottle feeding is eliminated as well. #3 is still comfortable around all of his caregivers when we enter with him, but he is definitely a binturong and is extremely comfortable and thriving with his binturong family. While this is not the end of the story, it is most definitely headed in the right direction.

The next great step in their development will be to expand their world a bit more and give them access to their outdoor habitat. This will come when we are confident that they are large enough and can traverse everything safely. Once Bramble and the bintlets are all comfortable with the habitat, the next step will be to introduce these babies to their father, Baloo. He has seen them several times through the mesh of his den, and both him and the bintlets were quite interested in each other, but they have not had physical contact yet. Baloo is such a great guy though; we are expecting these introductions to go well. Hopefully within the next few months, we will have the whole family together and on habitat for everyone to watch and enjoy.   

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