Detroit Zoo Sends 6,855 Endangered Crested Toad Tadpoles to Puerto Rico

Nearly 7,000 tadpoles just made a very long journey from Michigan to a Puerto Rican rainforest — and the people behind the trip have been at it for decades.

According to the Detroit News and ClickOnDetroit, the Detroit Zoo recently sent 6,855 Puerto Rican crested toad tadpoles to Río Encantado, a rainforest area in Manatí, Puerto Rico, where they will be released into the wild as part of a long-running conservation effort to help the critically endangered species recover.

“Each of these tadpoles represents a lot of care, coordination and hope,” Mark Vassallo, curator of amphibians for the Detroit Zoological Society, said in a statement, per the outlets.

“Amphibians are facing serious challenges globally, and efforts like this show how zoos and the communities that support them can play an important role in protecting vulnerable wildlife,” added Vassallo.

PEOPLE reached out to the Detroit Zoo for further comment.

The crested toad is the only toad native to Puerto Rico and was once thought to be extinct in the wild.

Found only on the island, it relies on healthy habitat and temporary freshwater pools to breed — conditions increasingly threatened by habitat loss, rising sea levels and invasive species, including the larger marine toad introduced to Puerto Rico, according to the Puerto Rican Crested Toad Conservancy.

The Detroit Zoo’s effort is part of the longest-running amphibian reintroduction program in the world. Organized captive breeding and reintroduction efforts for the species first began in 1984 under the Association of Zoos and Aquariums’ Species Survival Plan, making the Puerto Rican crested toad the first amphibian ever placed on such a plan, according to the conservancy. More than 20 zoos and organizations now participate in the effort collectively.

This latest release brings the Detroit Zoo’s all-time total to 143,195 tadpoles raised and released to date.