Bill Laitner

Detroit Free Press

DETROIT — With frogs and toads reeling worldwide from environmental threats, the Detroit Zoo is breeding endangered ones by the thousands.

The latest success in the zoo's amphibian bedroom? Zookeepers raised exactly 5,635 tadpoles — offspring of the endangered Puerto Rican crested toad, according to a news release. And those tads are getting what many humans might like: a one-way ticket to life in the Caribbean.

"Bolstering the population of these amphibians in their natural environment is a triumph for conservation," said Dr. Ruth Marcec, director of the National Amphibian Conservation Center. These tadpoles were to leave the zoo in Royal Oak on Wednesday for release into the wild at Puerto Rico's El Tallonal biological reserve, zoo officials said.

Those tadpoles will join the more than 47,000 previously produced at the zoo in its decade-old and award-winning National Amphibian Conservation Center. The breeding program for the Puerto Rican crested toad began in 1999, according to a news release Wednesday.

"Amphibians are in crisis, with nearly half of the world’s known 7,660 species threatened by extinction due to habitat loss, climate change, pollution, infectious diseases and other factors,” said Marcec, a veterinarian and reproductive physiologist who has been called the zoo's own "Dr. Ruth," after Dr. Ruth Westheimer, a sex therapist and media personality who was popular in the 1980s.

Amphibians are challenging to breed in captivity, and Marcec is an expert on getting them in the mood.

"They need some Marvin Gaye,” she quipped last month, in an Associated Press story.

Actually, they need a specific barometric pressure, precise rainfall and recordings of mating calls, she said then. The payoff? When their numbers are replenished in the wild, they keep water cleaner and help support a complete, healthy ecosystem of plants and organisms.

The Puerto Rican crested toad has greenish-brown pebbled skin and marbled golden eyes; it grows to about 4 inches long and can nearly flatten its body to hide in rock crevices. The zoo's breeding program is part of a nationwide system that ensures production of healthy, genetically diverse offspring of endangered species, the zoo's news release said.

Follow Bill Laitner on Twitter: @Bill_Laitner

Related:

Animal extinction happens more often than you think

'Biological annihilation:' Earth’s 6th mass extinction is underway