What Do Zoo Animals Do When It Gets Cold?
Zoos let us see animals from far-away places that many of us will never get to visit — often places with very different climates. So you might wonder: How do those zoo giraffes and lions make it through a cold winter?
We spoke to Bill Zeigler, senior vice president of animal programs at the Brookfield Zoo, located just outside cold and snowy Chicago, about the work they do to keep all kinds of species healthy and content through the winter months.
At Home, Indoors and Out
You may not realize this because the spaces are usually not visible to the public, but animals you see exhibited outdoors typically have access to some kind of indoor area.
"All animals have holding areas or what you could call night houses — they may be barns, they may be a series of cages or say giraffes, antelope, rhinos may have large stalls," says Zeigler. These behind-the-scenes areas usually aren’t as big as the exhibits, but they provide all the comforts needed in inclement weather. "There’s bedding, there’s water; the holding areas are cleaned every day just like the exhibits are," he says.
Inside, it’s warm enough for comfort in the winter, but it’s not really hot, because a big temperature difference isn’t good for the animals.
"If it’s 20 degrees outside and the holding area is 75 degrees, going back and forth is difficult, so the barns are maintained at a lower temperature, more like 45 or 50 degrees," he says. "It’s better for the animals — even the more tropical animals put on a coat during the cooler seasons."
And the animals aren’t the only ones who put on coats! That’s because the areas are maintained for the comfort of the animals instead of people. "Our keepers are the ones that have to wear coats when they work in them," Zeigler says.
It’s Cold There, Too!
Unless conditions are extreme, animals are generally given a choice of whether they prefer to be indoors or outdoors. And if you’re not a geography whiz, you may be surprised by some of the animals that are perfectly fine with the cold.
"People think rhinos come from the tropics," he says. "Well, they do come from Africa, but not the tropics. Even at the equator they are found at high elevations where there is snow on the ground."
In fact, there are plenty more species that may surprise you. "We’ll have visitors come out to the zoo when we’ve got 8 or 10 inches of snow on the ground and see the tiger or leopard out there and say, ‘Oh my God, what are you doing?’ Well, that’s where this tiger lives," Zeigler says. "People think ‘tigers, India — it must be really hot.’ Well, Amur leopards and Amur tigers come from eastern Russia and northern China, where it is cold as heck. They are out all year long."
Big animals also tend not to get cold as easily as smaller animals do. Even without a thick coat, a big body loses heat a lot more slowly, so don’t worry about those elephants — they are perfectly fine. "People forget, elephants came over the Alps with Hannibal," he says. "Elephants can take the cold, too. We’ll open up the barn doors and a lot of them will say, ‘I’ll go out, it doesn’t bother me,’" he says. "They have such a big body mass. It takes a lot to get them cold."
What About Cabin Fever?
Still, some animals want to stay in or need to when the weather is severe. So keepers make sure they have things to do. "We provide things to play with and occupy the mind," he says. "We have things like food logs that they have to engage with to get treats to keep them stimulated."
Holding areas usually don’t have the natural appearance of exhibits, since that look is often mostly for the benefit of the public. Animals don’t care what something looks like as long as they can interact with it in an appropriate way, so keepers sometimes have more choices behind the scenes. "We might not provide a boomer ball or plastic toy out on exhibit — we’d do something more naturalistic," he says. "But in the night house, we have things like that. It’s all up to the creativity of the staff."
But on the whole, enrichment is actually not much different from what keepers provide on exhibit. That fancy scenery is the same every day for the animal, so they still need to be provided with change and choices. "Once you make an exhibit, you spend millions of dollars creating artificial rockwork and trees and pools and running water — after they’re in it for a few days, that’s it," he says. So on exhibit or off, staff are always providing enrichment to keep animals active and engaging in their natural behaviors.
Long Winter Naps
In the wild, some animals get through the winter by hibernating, but you may be surprised to learn that it’s not something they actually have to do. "Hibernation is a way to keep them surviving when food is not available," Zeigler says. "When you provide food, whether it’s cold or not, they won’t hibernate, and it’s not detrimental to them because they’re getting the nutrition to keep their body going."
So most zoo animals don’t hibernate, but there are some exceptions. Brookfield does have a program to have their brown bears hibernate. "We have a hibernation den that’s on exhibit, and we allow them to bulk up at this time of year and really put on the pounds," he says. But they don’t go into deep hibernation like in the wild. "We have cold days when our brown bears will come into the den, and they’ll sleep for a week at a time, but it’s not real hibernation."
In some cases, cold-climate animals can hibernate in their exhibit and don’t need indoor areas. Zeigler recently visited another zoo whose prairie dogs hibernate for the winter. They have a similar diet program to bulk up, and the exhibit is designed so they can burrow naturally. "If you allow them to dig down deep enough that they go down below the permafrost line, the dens stay at 55 degrees," he says. "That allows them to cool down and they go to sleep."
But if the exhibit doesn’t allow that — say it has a concrete bottom — they need to come indoors for the winter.
There are also reptiles and amphibians that will only breed if they go through a cold period, a process called brumation. But zoos only need to initiate that process if they’re trying to get the animals to reproduce. "They’ll stay active as long as you keep the temperature up, but they may not cycle into a breeding situation without that," Zeigler says.
It’s the fashion nowadays for us humans to eat seasonally, and Brookfield Zoo is unusual in that it wants its animals do the same — but not because it’s a fad. The zoo’s nutrition department is studying seasonal changes in natural diets in the wild. Perhaps surprisingly, these changes even occur in places without cold winters.
Think about a tropical primate, Zeigler says. "Not every tree in the forest fruits at the same time," he points out. "It’s different depending on the season, and each fruit has a different nutritional value and sugar content and so on."
Or consider antelopes, which are usually fed the same pellet-and-hay diet year round. "Even in Africa they go through a drought season — food becomes lower in quality and has less nutritional value," he says. "Then spring rains come, everything comes up and it’s lush, and that triggers the female to go into estrous."
Seasonal changes in diet even happen with animals that don’t eat plants. Brookfield has been involved in studying dolphins in the wild for 44 years and is now applying what its researchers have learned about their diets to the dolphins in their dolphinarium.
"Coming from Florida, I know that when I go fishing there, there are different fish that I fish for throughout the seasons, so that’s telling me that dolphins must be eating different fish too. We think that helps keep them conditioned and helps them go through reproductive cycles," he says. "We’re trying to do this with everything — we try to provide variety, and now we’re looking at the seasonal changes we can provide."
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