Chill Factors

What goes into caring for the zoo’s animals during a Chicago winter?

Holiday events aren’t the only reason to visit Lincoln Park Zoo in winter. The season also offers a unique perspective on how zoo animals handle Chicago’s coldest months of the year. For some with natural adaptations to cold climates—polar bears, Japanese macaques, snowy owls—it’s an easy transition. But even species native to warmer parts of the world can enjoy a day outside in the snow when the conditions are right. We chatted with Dave Bernier, the zoo’s general curator, about how winter shapes the Animal Care staff’s management of different species.

When can visitors see a black rhino play in the snow?

All the animals that go outside have temperature guidelines. The veterinarians help us put those together, and we update them every year. Keepers work with those ranges after consulting the National Oceanic and Atmospheric Administration’s website for the weather forecast.

If it’s below the minimum temperature in their range, the rhinos can’t go outside that day, no matter what, for their safety. But there’s a range where they can be outside for a short period of time if it’s sunny and the wind is low. We’ve got these different parameters. That’s why on some days we can get a snowfall and the rhinos can go outside if they choose. Or it’s a cloudy day but colder than before, so they remain indoors.

Akita, a male Japanese macaque, explores his troop’s forested habitat after a snowfall.

How about Etana, the rhinos’ giraffe neighbor at Regenstein African Journey?

She’s not likely to be outside when it’s below 40 degrees. Age also comes into play with her, because she’s 21 now. Keepers must use discretion for her outdoor access if there’s snow on the ground.

Because she might slip?

Yes, slip and falls are a consideration for hoofed animals, especially those with harder hooves, like giraffes and zebras. Snow can be fine for some, but they can’t get good traction on icy areas. Keepers have to go out and evaluate their exhibits.

The Bactrian camels and Sichuan takins, however, seem fine in wintry conditions.

They’re adapted to that environment. The takins’ hooves are softer and spread out, so they get better traction on a variety of surfaces.

Can keepers use salt to melt icy areas?

The only place we can use salt is Kovler Seal Pool because the harbor and gray seals live in saltwater. We have to use sand as a friction material in every other place.

How much snow shoveling is required?

Keepers do a lot of shoveling in the outdoor bird exhibits. The vultures and storks can handle a lot of snow by perching up higher, but we have to shovel out paths on the ground for them to come down to eat and walk around.

Zoo keepers who care for birds in outdoor exhibits break ice to provide open water for trumpeter swans and other waterfowl.

Bird keepers also put on waders and break up ice in the Swan Pond and Waterfowl Lagoon.

Those folks are super hardy. Keepers spend a lot of time ensuring the water remains open and free of ice. This allows the birds to be comfortable during the coldest of days. Despite the frigid air temps, the waterfowl are able to remain outside all year long, as long as there is open water.

In their native range, Chilean flamingos occupy habitats from sea level up to 14,000 feet in the Andes. Their ability to tolerate extreme conditions makes them well suited for Chicago’s harsh winters.

Visitors are often surprised to see flamingos outside in winter.

People always think of flamingos as tropical birds. The flamingos that reside at the zoo are Chilean flamingos, which can occupy land from sea level all the way up to 14,000 feet in the Andes. Chilean flamingos are well-equipped to handle Chicago’s winters.

Regenstein Macaque Forest was planned for a cold-tolerant species from the get-go.

If you want to provide outdoor access year-round, you pick a four-season animal or you make the exhibit a four-season space. We have a bit of both with the snow monkeys. They’re hardy enough to handle the weather, but there are heated rocks and fan-cooled and sheltered areas so they’ll be comfortable outside and choose to be there even when they have indoor access. Giving all the zoo’s animals voluntary choice and control over their environments is important.

Can you share another example of animals choosing how they use their exhibit?

The African penguins are good in cold weather, but they have a certain temperature threshold. If it drops to minus 15, let’s say, we wouldn’t want them outside. We can keep them inside or give them voluntary access to a holding area. We tested this out, and once they realized they could choose their location, they freely moved between those two spaces and made good choices. It also helps that the entire penguin deck is heated to prevent it from getting icy or accumulating snow. We also make sure they eat a lot in winter because they’re burning more calories then.

Male black bear Kitai is less active during winter but continues to forage in his wooded habitat.

Do the zoo’s black bears hibernate in winter?

There’s no reason for us to facilitate hibernation. It’s risky; you’d have to watch them constantly, and the conditions have to be right. Our bears reduce their activity level but will keep eating all the way through winter.

We only have a few animals for which we purposefully encourage hibernation—namely reptiles, which must hibernate to reproduce successfully.

(Photos: Todd Rosenberg, Chris Bijalba, Julia Fuller)