A colobus monkey at the Maryland Zoo. Courtesy of the Maryland Zoo.

At the Maryland Zoo in Baltimore, visitors typically go from one exhibit to the next to see the animals on display. Starting next month, some of the animals will get a chance to move from one part of the zoo to another to see the visitors.

The Colobus Trail is the name of an $800,000 overhead walkway being constructed to give the zoo’s colobus monkeys a chance to leave the indoor confines of the Chimpanzee Forest building, part of the zoo’s African Journey section, and explore the outdoors for the first time.

In the process, it will give zoo visitors a new way to see animals that have up to now always been indoors and behind glass.

Inspired by similar projects at the Philadelphia Zoo and elsewhere, the elevated walkway is part of an effort to improve living conditions for primates by letting them move around the zoo grounds in ways they can’t today.

In addition to the colobus monkeys, the zoo’s eight lemurs will be able to use the overhead trail to move from the Chimpanzee Forest building to three outdoor habitats nearby, roughly the equivalent of a city block away.

If this first overhead walkway is a success, officials said, it could someday be expanded to give other animals a chance to move around the zoo in a similar fashion.

Karl Kranz, executive vice president for animal programs and chief operating officer for the zoo, said the Colobus Trail will enhance the quality of life for the animals that use it by giving them a chance to move around on their own and be exposed to different kinds of stimuli. But a big side benefit, he said, is that it will enhance the visitor experience.

“This is an animal welfare improvement, but what we’re finding is the public really likes it, too,” he said. “You’re seeing [the animals] in a different way.”

Colobus monkeys “are climbers,” said Don Hutchinson, the zoo’s president and CEO. “They like to be up in the air. They’re athletic. We expect them to be very mobile out on the walkway, and we think the people will love it.”

Construction began last month on the Colobus Trail, which has an indoor component and an outdoor component, both raised about 12 feet off the ground.

The indoor portion, already largely in place, is an enclosed walkway that’s suspended from the ceiling of the Chimpanzee Forest building, with connections to the colobus monkey and lemur habitats there. About three feet wide and three feet high, the section is covered with stainless steel mesh and has a Plexiglas floor so visitors below can see the animals moving around.

The outdoor portion, now under construction, is a tubular structure that will be hung from a cable suspended from posts. The enclosure will consist of a series of aluminum hoops, about three feet in diameter and covered by steel mesh.

When complete, the overhead trail will connect the Chimpanzee Forest building to the three outdoor pavilions along Lemur Lane, without crossing any pathways used by zoo visitors.

Overhead pathways such as the Colobus Trail have proven to be crowd-pleasers at other zoos and have been credited for giving visitors a new way to observe and learn about animals living in captivity.

The Philadelphia Zoo pioneered the concept when it opened its Treetop Trail for monkeys and lemurs in 2011. Elevated trails also have been installed at zoos in Jacksonville, Florida, and Louisville, Kentucky, among other locations.

As part of a project called Zoo360, the Philadelphia Zoo has built an entire network of see-through mesh trails on its campus that are used by many different species. Besides the Treetop Trail for monkeys and lemurs, it has the Great Ape Trail (used by orangutans and gibbons), the Big Cat Crossing (for tigers, lions, pumas and snow leopards) and the Gorilla Treeway.

Construction of the skywalk is underway at the Maryland Zoo. Courtesy of the Maryland Zoo.

“One of the most popular ones in Philly is… an overhead chute that their tigers have access to,” Kranz said. “You could walk down the main path and look up and there could be two tigers laying in the chute watching people go by. Their system is set up so that, by opening and closing doors, different animals can use it. If a big cat is in the chute, you don’t put anything else in there. But they’re set up so they can be used by multiple species.”

Philadelphia has found that their animals “actually enjoy the journey” of moving along the sky-trails and getting views they don’t have from their own habitats, said Kranz.

Hutchinson said it was a now-former zookeeper at the Maryland Zoo who saw the trail system in Philadelphia and thought a version would work well in Baltimore.

Kranz and media relations specialist Claire Aubel noted that the lemurs can go outdoors now, but they have to be carried in “sky kennels” from the Chimpanzee Forest building to the pavilions on Lemur Lane. Once the skywalk is operational, they said, they’ll be able to make the trip on their own.

Funding for the Colobus Trail was provided by the residents of Baltimore County, the Baltimore County Council and County Executive Johnny Olszewski Jr. The project is being designed and constructed by CLR Design and A Thru Z Consulting and Distributing Inc. as part of a design-build contract with the zoo. Both companies worked on the pioneering trail system at the Philadelphia Zoo.

According to the zoo, colobus monkeys are native to the forests of equatorial Africa and are highly social animals that spend most of their time in the treetops. The ones in Baltimore–Bisi, Gonzo and Dexter–are black and white colobus monkeys, distinguishable by their black bodies and long white tails. All three are male.

Construction on the Colobus Trail is expected to be finished by mid-November. Once finished, the colobus monkeys and lemurs will get access to the indoor section of the trail first so they can acclimate to it. Access to the outdoor section will follow, with the timing depending on outside temperatures and weather conditions.

Hutchinson said the Maryland Zoo has the potential to expand its overhead trail system for use by other species the way Philadelphia has, but administrators will want to see how well the initial trail works out first.

“This is the start for us,” he said. “It’s a prototype for what might happen in the future.”

Ed Gunts is a local freelance writer and the former architecture critic for The Baltimore Sun.