While winter gusts send shivers through Baltimore, the Baltimore Zoo's Massai lions are sitting pretty -- and warm -- on specially designed "hot rocks." Heated to about 65 degrees Fahrenheit, the rocks are one of the ways the staff makes cold weather bearable for sun-loving animals.
Most zoo animals remain in their usual areas during the winter, and with half-price admission during January and February, a winter zoo visit is both a bargain and a chance to see how the zoo and its residents weather the chilly seasonal changes.
Of course, the arctic foxes and polar bears make the adaptation quite nicely. Their coats grow thicker and change color during the winter months, and they are more active.
"Most animals adapt well to the winter," says Brian Rutledge, the zoo's director.
A winter zoo visit requires a minimum of adaptation on the part of humans as well -- a few extra layers of clothes and a sense of adventure.
"The most significant advantage to coming to the zoo in the winter is privacy to enjoy the animals," says Mr. Rutledge, adding that "many animals are more active in the cold."
The winter difference becomes apparent immediately after passing through the zoo's main entrance: crowds are considerably thinner now than during May and June, when the zoo welcomes a large portion of its annual attendance.
(Of the more than 450,000 people who visited the zoo in 1991, only about 11,700 visited in February, compared with more than 99,000 in May. According to zoo officials, on a single day in June last year, more people stopped by the zoo than during the entire month of January.)
So you'll be able to easily negotiate your way in a clockwise sweep around the zoo to see the changes winter has brought. The first stop might be a visit with the arctic foxes, animals that have changed in appearance since last summer.
The foxes "look very different now," says Cathy Tompson, the zoo's curator of education. "In the warm months, they are brown . . . leaf-colored. In the fall, they started turning a mottled combination of white and brown, and then finally white. Of
course, it gives them great camouflage in the Arctic."
In nearby cages, heat lamps keep animals like the white-cheeked gibbon warm. (His amazing siren-like call is easier to hear without a noisy crowd.) Plastic covering over the Bali mynah's bird cage keeps down the chill.
Down the hill from the arctic foxes, the polar bears, Anana and Magnet, alternate between swimming and basking in lukewarm sunlight.
"Polar bears, to some degree, have some of the same adaptations that the arctic fox does -- short, very furry ears and thick, stocky legs. Their paws also have fur on the bottom to give them insulation from the cold," says Ms. Tompson, explaining that legs and ears are the first body parts to chill.
Winter-loving animals tend to be short and heavily furred. Desert animals, in contrast, have large ears and long legs to rid themselves of heat.
A short walk down from the polar bears, flamingoes and South American waterfowl seem none the worse for the weather.
"People often wonder why duck's feet don't get cold in the water," says Ms. Tompson. Ducks have a network of closely intertwined veins and arteries in their legs so that blood leaving the warmth of their down-covered bodies doesn't have time to cool. Instead, heat is quickly reabsorbed by the circulatory system. "Sometimes ducks don't feel it as ice forms around their legs," says Ms. Tompson. "They can actually get stuck."
The zoo's ducks and other animals don't run this risk, though. At night, virtually all animals are taken indoors, primarily to protect them from natural predators (foxes, horned owls and raccoons) that roam the park.
Besides maintaining adequate heat for the warm-weather animals, Mr. Rutledge says other accommodations include plastic sheeting on doors, increased dietary protein and carbohydrates and heavier bedding.
Herons and other birds that frequent the Children's Zoo have moved to warmer quarters on the zoo's property. They will appear again next spring. But contrary to popular belief, the zoo's black bears are not actually hibernating.
"There's a big difference between what bears do [during the winter] and true hibernation," says Ms. Tompson. "When animals really hibernate, their body temperature drops to 40 degrees [Fahrenheit] and their heart rate and breathing drop [to only a few beats and breaths per minute]. During the winter, a bear's body temperature only drops 6 to 8 degrees and breathing slows slightly." She adds that the largest animal that truly hibernates is a groundhog or woodchuck.
For winter zoo visitors who make a morning call on Pete and Molly, the black bears, there is plenty of activity to watch. To simulate food foraging in the forest, zoo keepers hide oranges, peanut butter and celery in nooks and crannies of rocks and tree trunks in the bears' living quarters.