That’s not a car alarm.

Tis the symphonic sounds of two little white-cheeked gibbons who are super stoked about going outside at Cheyenne Mountain Zoo.

Every morning, as their keepers prepare their outdoor exhibit for the day, 39-year-old Debbie and 34-year-old Tanh Linh sing a song of unbearable ecstasy as they impatiently wait. These two can belt as well as any seasoned Broadway performer. Debbie kicks things off in the well-rehearsed duet, Tanh Linh breaks in for a solo, and his mate returns to polish off the tune. Press repeat.

“It’s one of the ways they both affirm their territory and pair bond,” said keeper Carrie Supino. ‘They’re telling all the other gibbons in Colorado this is their area, their space, just as they would if they were in the jungle. That call carries for several miles and it’s really long and loud and they would typically do it every morning.”

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Finally, the two are released into their mountain space, decorated with old fire hoses and dangling apparatuses to climb and swing from and rocks to scramble. Tanh Linh enters first, with a swagger resembling a cowboy walking into an Old West saloon. His unusually long arms dangle almost to the ground. Debbie scampers in behind him, drops to the earth and picks up a puzzle feeder, eager to ferret out a piece of zucchini or cucumber. Today her explorations score her a thick slice of onion, which she slowly chews while staring off into space, stopping briefly to peel off the brown skin.

Which is which?

Debbie, who clocks in at 15 pounds, is the whitish, buff-colored female and Tanh Linh, at 16 pounds, is the darker-colored male. That’s typical for gibbons, who are sexually dichromatic — females are always buff-colored, males are dark. And they’re named white-cheeked gibbons due to the males’ white cheeks. Females have a black spot on their heads.

Debbie is the more bold and confident of the pair: “She’s a strong, independent lady,” Supino said. Tanh Linh is more laid-back. But they love to groom each other and snuggle. Keepers often find them napping together.

“They complement each other nicely in that way,” Supino said. “Female gibbons tend to be more dominant in terms of getting access to food and resources first. Tanh Linh stays out of her way and gives her her space. They navigate each other pretty well.”

Are gibbons monkeys?

No. They’re lesser apes from southeast Asia, predominantly Malaysia, Vietnam and China. They don’t have tails, which distinguishes them from monkeys, plus they also live longer. And most species of gibbons are endangered to some degree, due in large part to their natural habitat being cleared to produce palm oil. To help gibbons and orangutans in the wild a new app, PalmOil Scan, produced by the World Association of Zoos and Aquariums and co-led by Cheyenne Mountain Zoo, helps consumers decipher which food products are using sustainable palm oil.

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Partners for life

Debbie Gibbon (those who know ’80s pop music will get the reference) and Tanh Linh have been a mated pair for more than two decades. Gibbons are one of the creatures closest to monogamous in the animal kingdom, and mostly mate for life. The couple did have one baby, though it’s moved on to another zoo and there are no plans for more. The two will simply be companions to each other for the rest of their days, which could be quite some time, seeing as they’ve outlived their median life expectancy of 30.

“They’re two of our healthiest animals in the building (Primate World),” Supino said. “They don’t require any medications. They’re both active. For their age and how long they’ve been together, they do really well.”

Snacks and stuff

Gibbons are omnivores that mostly eat leafy greens and other vegetables, peanuts, fruit and specially made primate biscuits, which contain nutrients to round out their diets. They also love a hardboiled egg, which mimics their behavior in the wild, where they might go after bird eggs, reptiles or insects.

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Those limbs

Supino once measured Tanh Linh’s arm span, and it was almost as long as hers. Typical arm span for a gibbon is 5 to 6 feet. These little guys are built for a life in the tree tops, where they swing from limb to limb, and can jump 30 to 40 feet across gaps in trees in the wild. Those arms also turn them into award-winning tightrope walkers, as they stretch them out to the sides while balancing on tautly stretched fire hoses.

Contact the writer: 636-0270