Tilly’s baby river otter has a name. The 6-week-old pup will be called Zigzag, or Ziggy for short — named after the 12-mile-long Sandy River tributary that flows down Mount Hood through Zigzag Canyon.

“A lot of the animals here get their names from nations or cultures associated with the species’ 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.”

After narrowing their list of potential names to three choices — Trask and Willamette were the other two — keepers last week invited the public to vote for their favorite via the zoo website. More than 8,000 otter fans weighed in, with Ziggy earning close to 50 percent of the votes.

Both Tilly and Ziggy are doing well, according to Christie, and visitors can now see them from time to time through a den window at the Cascade Stream and Pond habitat. The young pup, born Nov. 8, has recently opened his eyes and started to walk a bit, right on schedule. River otters usually open their eyes after four to five weeks, and begin walking at about five to six weeks.

“Young river otters are very dependent on their moms, and Tilly has been very nurturing,” Christie said. “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.”

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

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 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. (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 here 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.