Species that are hanging on lay their eggs in the forest, in pools or leaf litter. They either have no tadpole stage, or the tadpoles grow to adulthood away from the streams. This pattern has been confirmed at other sites in Costa Rica and in Australia as well. But that finding, though important, doesn't explain the frogs' susceptibility. After all, the rivers flow into the lowlands, where frog populations remain relatively healthy.
Elevation is a vital but still-undeciphered clue.
In Central America and Australia, affected species have been those that live above 1,500 feet. Die-offs in the United States, Canada, and Brazil also have been in mountainous areas. The Central American die-offs spread southeast along the mountain ridges from Monteverde in 1988 down to Fortuna in 1996. Lips believes that all were caused by the fungus. S cientists must delve deeper to understand what is happening.