Aardwolf
Well-Known Member
For today’s post, we’ll talk about one of the most popular of all zoo mammals in the US, the North American river otter. It’s easy to see why this species is so popular – they are very active and engaging, tolerant of a wide variety of climatic conditions, and, by virtue of their broad geographic range, can be incorporated into native-themed exhibits across the country. Being aquatic, they are also often seen in aquariums, as well as nature centers.
My experience with river otters (NAROs, as they’re often called) at one AZA facility. We managed 1.1 (for the most part – more about that at the end) in an outdoor exhibit that consisted of a large pool, about three feet or so at the deepest, and an adjacent land area that was soil substrate with some rocks and sparse vegetation. A nest box with shavings was the main shelter, but they also often used a large hollow log as a sleeping space, especially in the warmer months.

The natural substrate was a favorite part of mine for the exhibit – I see a lot of otters in indoor exhibits, especially at aquariums and nature centers, and I dislike all of the concrete. It seems like some of those exhibits are designed with the idea of showing visitors otters swimming underwater, and don’t think beyond that as far as the animal’s needs. Left to their own devices in a naturalistic setting, otters will dig in dirt, climb low trees, roll through piles of raked leaves, and spend lots of time on the ground (a lot of this applies to polar bears as well, I find). A good otter exhibit isn’t just a pool, and should incorporate varied land area as well. We didn't have underwater viewing at our exhibit, and to be honest, I was okay with it.
Cleaning the exhibit was very easy - just rake up a few small piles of poop (usually colored bright orange because of the carrots, and a bit slimy because of the fish), and strip out the next box once a week or so. Once a week, we'd drain the pool, power-washing as needed (it was an older exhibit, so it was a dump and fill rather than having a filtration system).
Otters are very active, so not surprisingly they burn lots of calories. When I started at the zoo, we fed the otters twice a day; by the time I left, we were doing it four times a day (same amount of food, just broken up more). This had the added advantage of making the otters more active throughout the day, so they weren’t treating the middle of the day as dead time. Diet was mostly fish-based (like the pelicans, we tried keeping the otters on a diverse mix of fish species – capelin, herring, sardines, butterfish, trout) – as well a carnivore diet (ground horsemeat-based), and a little chopped produce, especially carrots. Life fish (especially eels) and shellfish, as well as bones, were used for dietary enrichment.
Figuring out how to slow down the feedings was a challenge, as otters are ravenous. We used a lot of enrichment features to extend feeding, such as putting small fish in water cooler jugs that we’d sink into the bottom of the pool, or putting carnivore diet in PVC pipe feeders.

Otters getting chopped fish out a puzzle feeder one of our keepers made of out PVC caps. It was always a challenge coming up with new enrichment for the otters, as they quickly learned how to solve most puzzle feeders.
Being so intelligent and so inquisitive, it’s not surprising that otters respond very well to training, which also provides good enrichment. We trained for a variety of behaviors, such as scale-training (getting an otter to actually sit still is a challenge!), opening the mouth, showing paws, and standing for injections.
We had hoped to breed our otters, but this was unsuccessful. At first we’d hoped that separating the pair for a month prior to breeding would be the trick, but it wasn’t. The male would enthusiastically mate with the female both on land and water, but she never got pregnant. The SSP has since determined a likely cause – many otters in zoos and aquariums are wild born, non-releasable animals (one of other birds was a hurricane orphan), and males and females from different parts of North America are brought together as pairs. Different parts of the country have different climatic conditions, and as a result an otter from, say Louisiana and one from, say, Massachusetts might come into cycle at different times of the year. The SSP is now working to pair animals that are closer in geographic origin.
We very seldom, almost never, went into our otter exhibit with the animals, which wasn’t too big of a challenge as they shifted very well due to their food motivation (I always enjoyed watching them in holding, flipping in loops as they waited for us to let them back out for feeding). Our male was a bit… slow, to the point that we joked that he was dropped on his head, and often seemed to be in his own little world. I sometimes wondered if he was partially deaf or something, since the female was always ready to shift, but he seemed to not know that we were there, especially if he was in a log or nest box. Sometimes, I’d have to go in and look for him to drive him to the shift area. The fear of going in with the otter was caused by the experiences of a former keeper, many years earlier, who was badly bitten by an otter, even falling into the pool as he tried to escape it.
Towards the end of my time at this zoo, a local community museum was looking at replacing its large fish tank with an indoor otter exhibit, and asked us to come and consult. We came and offered our advice, which was, in general, don’t do it (or, since I’m a bit more diplomatic, you could do it, but to do it well would involve a lot more expense and effort than you seem to want to put into this). They… opted not to listen. More frustratingly, they also opted to get their otters before the exhibit was done, and someone sweet-talked our director in having us hold the otters while they finished up. This pair of youngsters had just been wild caught down south, and they were as squirrely and slippery as you could imagine, to say nothing of terrified of us and everything.
We didn’t really have a place to put them, so they were at first housed in one of our covered waterfowl holding pens, off-exhibit. They dug out the very first night, but thankfully into the keeper area, rather than the great outdoors. I was quite relieved when we finally packed them off to their new home in the museum.
Being part of our native wildlife exhibit, it wasn't surprising that we occasionally saw wild otters locally, once even swimming on the creek that ran through the zoo. On another occasion, we received a call from a nearby resort town that had a waterpark - a female otter had recently been found dead there, and a few days afterwards, her two young pups were found wandering about. We went down and captured them, bringing them back to the zoo to care for in our hospital. We then worked with the SSP to find placement for them, together, an another facility.

Otter pups in the zoo hospital
It's interesting to me that NARO are an SSP, actually. For so many other native species, such as black bears, bobcats, and bald eagles, the expectation is that there will always be non-releasable animals in need of placement, and so zoos SHOULDN'T breed those species, in order to keep spaces free for wild-born animals. Otters (as well as beavers and North American porcupines) are managed as SSPs, even though it's quite common that non-releasable animals are found and brought into zoos - which also means that those populations get constant influxes of wild genes that most SSPs could never obtain.
My experience with river otters (NAROs, as they’re often called) at one AZA facility. We managed 1.1 (for the most part – more about that at the end) in an outdoor exhibit that consisted of a large pool, about three feet or so at the deepest, and an adjacent land area that was soil substrate with some rocks and sparse vegetation. A nest box with shavings was the main shelter, but they also often used a large hollow log as a sleeping space, especially in the warmer months.

The natural substrate was a favorite part of mine for the exhibit – I see a lot of otters in indoor exhibits, especially at aquariums and nature centers, and I dislike all of the concrete. It seems like some of those exhibits are designed with the idea of showing visitors otters swimming underwater, and don’t think beyond that as far as the animal’s needs. Left to their own devices in a naturalistic setting, otters will dig in dirt, climb low trees, roll through piles of raked leaves, and spend lots of time on the ground (a lot of this applies to polar bears as well, I find). A good otter exhibit isn’t just a pool, and should incorporate varied land area as well. We didn't have underwater viewing at our exhibit, and to be honest, I was okay with it.
Cleaning the exhibit was very easy - just rake up a few small piles of poop (usually colored bright orange because of the carrots, and a bit slimy because of the fish), and strip out the next box once a week or so. Once a week, we'd drain the pool, power-washing as needed (it was an older exhibit, so it was a dump and fill rather than having a filtration system).
Otters are very active, so not surprisingly they burn lots of calories. When I started at the zoo, we fed the otters twice a day; by the time I left, we were doing it four times a day (same amount of food, just broken up more). This had the added advantage of making the otters more active throughout the day, so they weren’t treating the middle of the day as dead time. Diet was mostly fish-based (like the pelicans, we tried keeping the otters on a diverse mix of fish species – capelin, herring, sardines, butterfish, trout) – as well a carnivore diet (ground horsemeat-based), and a little chopped produce, especially carrots. Life fish (especially eels) and shellfish, as well as bones, were used for dietary enrichment.
Figuring out how to slow down the feedings was a challenge, as otters are ravenous. We used a lot of enrichment features to extend feeding, such as putting small fish in water cooler jugs that we’d sink into the bottom of the pool, or putting carnivore diet in PVC pipe feeders.

Otters getting chopped fish out a puzzle feeder one of our keepers made of out PVC caps. It was always a challenge coming up with new enrichment for the otters, as they quickly learned how to solve most puzzle feeders.
Being so intelligent and so inquisitive, it’s not surprising that otters respond very well to training, which also provides good enrichment. We trained for a variety of behaviors, such as scale-training (getting an otter to actually sit still is a challenge!), opening the mouth, showing paws, and standing for injections.
We had hoped to breed our otters, but this was unsuccessful. At first we’d hoped that separating the pair for a month prior to breeding would be the trick, but it wasn’t. The male would enthusiastically mate with the female both on land and water, but she never got pregnant. The SSP has since determined a likely cause – many otters in zoos and aquariums are wild born, non-releasable animals (one of other birds was a hurricane orphan), and males and females from different parts of North America are brought together as pairs. Different parts of the country have different climatic conditions, and as a result an otter from, say Louisiana and one from, say, Massachusetts might come into cycle at different times of the year. The SSP is now working to pair animals that are closer in geographic origin.
We very seldom, almost never, went into our otter exhibit with the animals, which wasn’t too big of a challenge as they shifted very well due to their food motivation (I always enjoyed watching them in holding, flipping in loops as they waited for us to let them back out for feeding). Our male was a bit… slow, to the point that we joked that he was dropped on his head, and often seemed to be in his own little world. I sometimes wondered if he was partially deaf or something, since the female was always ready to shift, but he seemed to not know that we were there, especially if he was in a log or nest box. Sometimes, I’d have to go in and look for him to drive him to the shift area. The fear of going in with the otter was caused by the experiences of a former keeper, many years earlier, who was badly bitten by an otter, even falling into the pool as he tried to escape it.
Towards the end of my time at this zoo, a local community museum was looking at replacing its large fish tank with an indoor otter exhibit, and asked us to come and consult. We came and offered our advice, which was, in general, don’t do it (or, since I’m a bit more diplomatic, you could do it, but to do it well would involve a lot more expense and effort than you seem to want to put into this). They… opted not to listen. More frustratingly, they also opted to get their otters before the exhibit was done, and someone sweet-talked our director in having us hold the otters while they finished up. This pair of youngsters had just been wild caught down south, and they were as squirrely and slippery as you could imagine, to say nothing of terrified of us and everything.
We didn’t really have a place to put them, so they were at first housed in one of our covered waterfowl holding pens, off-exhibit. They dug out the very first night, but thankfully into the keeper area, rather than the great outdoors. I was quite relieved when we finally packed them off to their new home in the museum.
Being part of our native wildlife exhibit, it wasn't surprising that we occasionally saw wild otters locally, once even swimming on the creek that ran through the zoo. On another occasion, we received a call from a nearby resort town that had a waterpark - a female otter had recently been found dead there, and a few days afterwards, her two young pups were found wandering about. We went down and captured them, bringing them back to the zoo to care for in our hospital. We then worked with the SSP to find placement for them, together, an another facility.

Otter pups in the zoo hospital
It's interesting to me that NARO are an SSP, actually. For so many other native species, such as black bears, bobcats, and bald eagles, the expectation is that there will always be non-releasable animals in need of placement, and so zoos SHOULDN'T breed those species, in order to keep spaces free for wild-born animals. Otters (as well as beavers and North American porcupines) are managed as SSPs, even though it's quite common that non-releasable animals are found and brought into zoos - which also means that those populations get constant influxes of wild genes that most SSPs could never obtain.












