Detroit Zoo Sends 7,000 Tadpoles to Save Rare Puerto Rico Toad

The Detroit Zoo just packed up 6,855 Puerto Rican crested toad tadpoles and sent them on a journey from Michigan to a rainforest in Puerto Rico, where they'll get a second chance at survival in the wild.

This isn't a one-time rescue mission. The zoo has been raising and releasing these critically endangered toads since the 1980s, making it the longest-running amphibian reintroduction program on Earth.

The Puerto Rican crested toad is the only toad native to the island and was once believed to be completely extinct in the wild. Today, the species clings to survival in temporary freshwater pools scattered across Puerto Rico's rainforests.

"Each of these tadpoles represents a lot of care, coordination and hope," said Mark Vassallo, curator of amphibians for the Detroit Zoological Society. His team knows that amphibians worldwide face serious threats, and programs like this prove zoos can make a real difference.

The species faces mounting challenges. Habitat loss, rising sea levels, and invasive species like the larger marine toad all threaten the tiny crested toad's survival. Those temporary breeding pools they depend on are becoming harder to find.

The Ripple Effect

This release brings the Detroit Zoo's all-time total to more than 143,000 tadpoles returned to Puerto Rico. But the impact goes far beyond one zoo's efforts.

More than 20 zoos and conservation organizations now work together on this rescue, coordinated through the Association of Zoos and Aquariums' Species Survival Plan. The Puerto Rican crested toad earned the distinction of being the first amphibian ever included in such a plan back in 1984.

That collaboration shows what's possible when institutions pool their resources and expertise. Each participating zoo breeds tadpoles, shares knowledge, and contributes to keeping an entire species alive.

The program has become a blueprint for saving other endangered amphibians around the world. What started as an emergency effort to save one toad species has evolved into a model for wildlife conservation.

Those 6,855 tadpoles swimming in Puerto Rico's rainforest pools right now carry more than just their own DNA forward—they represent four decades of people refusing to give up on a species that deserves to thrive.