Sikorski may have been the warmest man in Philadelphia on Tuesday. And certainly he was one of the few who didn't need socks on the job.
The outdoor temperature stood at 9 about noon, and gusts of 30 m.p.h. drove the wind chill to 11 below zero. Inside, as waves of mist floated from machines, Sikorski went about his work, a walkie-talkie on one hip and a pair of plant snippers on the other.
He fed the poison-dart frogs, which become nontoxic on a special academy diet, whistling to call them to lunch. They live in a closed case within the 1,200-square-foot exhibit. He put out food for the butterflies, which taste with their feet. He cut dead leaves from the jungle of tropical plants.
"This job suits me well," Sikorski said. "I'm good at nurturing things. I love talking to people, the visitors. I love coming here, meeting different people all the time. It's like traveling every day."
Sikorski, of Northern Liberties, is not a lepidopterist, a degree-holding expert who studies and classifies butterflies. His college degree is in art. But if you're interested in a discussion of the light receptors in the compound eyes of butterflies, he's your guy.
Sikorski was interested in insects even as a boy and collects them now - but only if they're already dead. "I'm always looking on the ground," he said, because he wouldn't want to kill a bug.
He didn't intend to become the academy butterfly coordinator. After college, he worked in an art-supply store while pursuing his craft, which includes acrylic portraits of insects that look real enough to walk off the canvas.
At the academy, he started out in spiders - and as a volunteer, moved by an interest in helping people understand nature. That was 20 years ago. He subsequently took a part-time job and then, in 1998, became the full-time manager of the exhibit, "Butterflies!"
As many as 40 species are brought here from Central and South America, East Africa, and Southeast Asia, arriving while still in the chrysalis stage.
They emerge in a sealed chamber before being released into a lush garden, where they create the museum's second-most-popular exhibit, behind only the giant skeletons of Dinosaur Hall.
Sikorski spends his days surrounded by color - the innumerable shades of green in the plants, the flashes of iridescent blues, oranges, and yellows on the wings of the butterflies. The insects are comfortable around visitors, few of whom ventured into the exhibit on a frozen Tuesday.
"They don't see us as predators," Sikorski said. "We don't look like predators, we don't smell like predators."
Sikorski rode his bicycle to work Tuesday, as he does every day. He peddled while bundled in jeans and jacket, then changed to his tropical-climate gear at the academy.
Even the museum wasn't immune from the cold, the temperature in the butterfly exhibit hanging at about 82, down from the usual 85. Sikorski noticed the difference.
"Honestly, to me," he said, "it's a little chilly."