Why is the golden toad extinct?

Answer 1

As late as 1994, five years after the last sighting, researchers still hoped that B. periglenes continued to live in underground burrows, as similar toad species have lifespans of up to twelve years.[5] By 2004 IUCN listed the species as extinct, after an evaluation involving Savage (who had first discovered them 38 years earlier). IUCN's extinction was based on the lack of sightings since 1989 and the "extensive search[ing]" that had been done since without result.[3] Tim Flannery describes the extinction of the golden toad as Costa Rica's first extinction due to global warming,[4] but this is not the only explanation for the loss of the species that has been put forward. Jennifer Neville examines the different hypotheses explaining the extinction of the golden toad in her article "The Case of the Golden Toad: Weather Patterns Lead to Decline". Neville comes to the conclusion that Crump's El Niño hypothesis is "clearly support[ed]" by the available data.[5] IUCN gives numerous possible reasons in its description of the past threats to the species, including "[the golden toad's] restricted range, global warming, chytridiomycosis and airborne pollution".[3] Neville also mentions arguments that an increase in UV-B radiation, fungus or parasites, or lowered pH levels contributed to the Golden Toad's extirpation.[5] It has also been hypothesized that an invasive species, not native to the area, could have caused the extinction. Theorists claim that tourists brought this invasive species to Costa Rica. The years prior to the extinction of the golden toad, tourism grew exponentially in Costa Rica fueled by the new relative stability of the Costa Rican government and improved relations with the United States. Programs such as Peace Corps brought thousands of Americans to Costa Rica in this time period. Specifically, species from cold regions such as Chicago could thrive in warm climates. The introduction of a new species could have had detrimental effects on the small, golden toad populations. B. periglenes would have lacked much variation in genes due to restrictive nature of breeding within the same population. The mutation necessary to survive the new invasive species could have been lacking in B. periglenes. Pictures from one such Peace Corps volunteer, Peter Jude LoPresti, verify over 8 golden toads seen only months before their documented extinction. Invasive species theory could account for the rapidity of the golden toad's extinction