Category: Oregon Zoo

Tilly, a North American River Otter at the Oregon Zoo, gave birth to a pup on November 8 —her second this year. The new arrival weighed just shy of 5 ounces (28.3 g) at birth and has nearly tripled that thanks to mom’s naturally high-fat milk.

“We’re pretty sure this pup’s a male,” said Julie Christie, the zoo’s senior North America keeper. “But Tilly is very protective, so we can’t be positive until our vets conduct a more thorough exam.”

Tilly and her pup are currently in a private maternity den, and it will be another month or two before visitors can see them in their Cascade Stream and Pond habitat. Young River Otters usually open their eyes after three to six weeks, and begin walking at about five weeks.

“Young River Otters are very dependent on their moms, and Tilly has been very nurturing,” said Christie. “She did a great job with her first pup, Mo, earlier this year. She raised him up from this tiny, helpless creature into the sleek, agile, full-grown otter he is today. We’re confident Tilly will be a great mom to her new pup as well.”

Photo credits: Oregon Zoo

Surprisingly, swimming does not come naturally to River Otters; pups must be taught to swim by their moms. Earlier this year, this video of Tilly teaching Mo to swim drew more than half a million views on the zoo’s YouTube channel.

Take a peek behind the scenes as the newborn pup is weighed:

Keepers have yet to decide on a name for the new pup, though it is likely he will be named after a local river or waterway. (Mo is short for Molalla, after the Molalla River.)

North American River Otters typically give birth from late winter to spring, but Tilly seems to be on her own schedule, keepers say. The breeding season for River Otters is December through April, and actual gestation only lasts a couple of months. Unlike their European cousins however, North American River Otters usually delay implantation so that the time between conception and birth can stretch to as much as a year. That hasn’t been the case with Tilly. 

Christie said it is also unusual — though not unheard of — for an otter to give birth to a single pup, as Tilly has now done twice. Litters usually consist of two or three pups, though the range is anywhere from one to six. Family groups typically consist of an adult female otter and her pups, with males moving away once they reach adulthood.

Since both Tilly and the pup’s father, B.C., were born in the wild, they and their offspring are considered genetically important for the breeding otter population in North American zoos. Both parents are rescued animals who had a rough start to life.

Tilly, named after the Tillamook River, was found orphaned near Johnson Creek in 2009. She was about four months old, had been wounded by an animal attack and was seriously malnourished. Once her health had stabilized, Tilly came to the Oregon Zoo in a transfer facilitated by the Oregon Department of Fish and Wildlife, which oversees the species’ protection. 

The pup’s father, B.C. (short for Buttercup), was found orphaned near Star City, Ark., also in 2009. He was initially taken in by the Little Rock Zoo, but transferred to Oregon the following year as a companion for Tilly. The two otters hit it off quickly and have been playful visitor favorites ever since.

Now that the threat from fur trappers has declined, North American River Otters are once again relatively abundant in healthy river systems of the Pacific Northwest and the lakes and tributaries that feed them. Good populations exist in suitable habitat in northeast and southeast Oregon, but they are scarce in heavily settled areas, especially if waterways are compromised. Because of habitat destruction and water pollution, River Otters are considered rare outside the Pacific Northwest.

Metro, the regional government that manages the Oregon Zoo, has preserved and restored more than 90 miles of river and stream banks in the region through its voter-supported natural area programs. By protecting water quality and habitat, these programs are helping to provide the healthy ecosystems needed for otters, fish and other wildlife to thrive. River Otters are frequently observed in Metro region waterways.

Mo, a North American River Otter born at the Oregon Zoo in late January, took his first dip last week, but not without a lot of help from mom, Tilly. She initiated the swimming lesson by nudging Mo to the water's edge and then plunging in with a firm grip on the scruff of her pup's neck, just as otter moms do in the wild. Even though Tilly is a first-time mom, she has been doing all the right things for her pup, according to keepers.

"A lot of people don't realize it, but swimming doesn't come naturally to River Otter pups," said keeper Becca Van Beek. "They have to be taught to swim by their moms, and so far Tilly's been an amazing teacher. It might look kind of scary to a casual observer," Van Beek continued. "She'll grab Mo by the scruff of the neck and dunk him in the water. But that's a very natural behavior. Baby Otters are extremely buoyant, so Mo has built-in water wings! It's exactly what we've been hoping to see."

Now that the threat from fur trappers has declined, North American River Otters are once again relatively abundant in healthy river systems of the Pacific Northwest and the lakes and tributaries that feed them. Good populations exist in suitable habitat in northeast and southeast Oregon, but they are scarce in heavily settled areas, especially if waterways are compromised. Because of habitat destruction and water pollution, River Otters are considered rare outside the Pacific Northwest.

Photo Credit: Oregon Zoo/Shervin Hess

Upon baby-proofing the exhibit, zookeepers gave Tilly and Mo outdoor access during the mornings.  The best time for zoo visitors to catch them is between 9:30 a.m. and noon, though the Otters don't always decide to venture out.

Mo, named for the Molalla River, is the first River Otter to be born at the Oregon Zoo. He weighed around 4 ounces at birth, but has been growing fast and now is approaching 5 pounds. Adult River Otters usually weigh 11 to 30 pounds. You can read more about Little Mo, see more pictures and another video of the pup from a past post  HERE on ZooBorns.com.

Read more after the fold:

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After several weeks of consideration, keepers at the Oregon Zoo have settled on a name for the new baby River Otter. The pup will be called Molalla, or Mo for short, named after the Oregon river.

“A lot of North American zoo animals get their names from nations or cultures associated with their native habitats,” said Julie Christie, senior keeper for the zoo’s North America area. “For the River Otters, we like to choose names based on local waterways.”

Photo credits: Michael Durham / Oregon Zoo 

Mo’s mother, Tilly — named after the Tillamook River — gave birth to the pup Jan. 28. The first River Otter to be born at the Oregon Zoo, Mo weighed just over 4 ounces at birth but has been enjoying mom’s naturally high-fat milk and growing fast. He now weighs more than 2 and 1/2 pounds.

Tilly and her baby have occupied a private, off-exhibit maternity den since the birth, but keepers say zoo visitors have shown a lot of interest in the new arrival even though they can’t see him yet.

See and learn more below the fold…

“A lot of people wrote in to offer congratulations and make suggestions for his name,” Christie said. “Several people liked the name Willy, short for Willamette. And one visitor suggested naming him Pudding, after a tributary of the Molalla. We thought that was pretty cute.”

River Otters are very dependent on their mothers when they’re born. It’s usually three to five weeks before young otters open their eyes, and about five weeks before they first walk. Surprisingly, swimming does not come naturally to otters — pups must be taught to swim by their mom.

Christie said Tilly is continuing to do all the right things as a new mom, and the animal-care staff has been as hands-off as possible; they have only quickly examined Mo when Tilly is taking a short break from mom duty.

“We give her access to the exhibit during the day,” Christie said. “But Tilly’s been very attentive and doesn’t spend too long away from Mo. We’re pretty sure the pup’s a male, but we can’t be positive until our vets conduct a more thorough exam. Either way, we think Molalla will be a good name. There are plenty of females named Mo too.”

Keepers are working to “baby proof” the Cascade Stream and Pond section of the zoo’s Great Northwest exhibit and make sure it’s safe for the young otter. If all goes well, zoo visitors will be able to see Tilly and Mo there in a few weeks. Until then, otter fans are encouraged to follow the zoo on Facebook and Twitter for updates.

Since both Tilly and the pup’s father, B.C., were born in the wild, they are considered genetically important for the breeding otter population in North American zoos. Both parents are rescue animals who had a rough start to life.

Tilly was found orphaned near Johnson Creek in 2009. She was about 4 months old, had been wounded by an animal attack and was seriously malnourished. Once her health had stabilized, Tilly came to the Oregon Zoo in a transfer facilitated by the Oregon Department of Fish and Wildlife, which oversees the species’ protection.

The pup’s father, B.C., was found orphaned near Star City, Ark., also in 2009. He was initially taken in by the Little Rock Zoo, but transferred here the following year as a companion for Tilly. The two otters hit it off quickly and have been playful visitor favorites ever since. (B.C. arrived at the Oregon Zoo with the name Buttercup; when he was little, keepers thought he was female.)

Now that the threat from fur trappers has declined, North American River Otters are once again relatively abundant in healthy river systems of the Pacific Northwest and the lakes and tributaries that feed them. Good populations exist in suitable habitat in northeast and southeast Oregon, but they are scarce in heavily settled areas, especially if waterways are compromised. Because of habitat destruction and water pollution, River Otters are considered rare outside the Pacific Northwest.

Metro, the regional government that manages the Oregon Zoo, has preserved and restored more than 90 miles of river and stream banks in the region through its voter-supported natural area programs. By protecting water quality and habitat, these programs are helping to provide the healthy ecosystems needed for otters, fish and other wildlife to thrive. River Otters are frequently observed in Metro region waterways.

Committed to conservation, the zoo is currently working to save endangered California Condors, Oregon Silverspot and Taylor’s Checkerspot Butterflies, Western Pond Turtles and Oregon Spotted Frogs. Other projects include studies on Asian Elephants, Polar Bears, Orangutans and Giant Pandas. Celebrating 125 years of community support, the zoo relies in part on donations through the Oregon Zoo Foundation to undertake these and many other animal welfare, education and sustainability programs.

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