By Molly Daly

PHILADELPHIA (CBS) — On warm nights in the city’s Upper Roxborough section, American Toads make the trek from the woods of the Schuylkill Center for Environmental Education to an old reservoir nearby.

Dr. Carlos Martinez, a Philadelphia Zoo Amphibian Conservation Biologist, says these toads emerge from hibernation and head to a vernal pool to spawn.

“Those pools that form with the first snowfall, and the first rains in the spring,” he tells KYW Newsradio.

So the old Upper Roxborough reservoir is like a gigantic amphibian singles bar.

“In this particular area of the city is the only place where they breed in such large numbers,” he said.

And sing.

“The call that you hear at night is always the males trying to attract females,” he explains.

The Toad Detour was established to ensure the amphibians safe passage.

Martinez says he will be speaking April 7, for the second of two toad nights, at the Schuylkill Center.

“People can learn about the project, and visit the road where the toads cross, and possibly see a few toads,” he said.

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