Those lucky enough to have seen them will never forget.
For just a few days every year, the elfin cloud forest of Costa Rica comes alive with crowds of golden toads the length of a child's thumb, emerging from undergrowth to mate at rain-swelled pools.
In this mysterious woodland the cloud drapes over mountain ridges and "the trees are dwarfed and wind-sculpted, gnarled and heavily laden with mosses," says Alan Pounds, an ecologist at the Monteverde Cloud Forest Preserve. "The soils are very dark, and so golden toads stood out. Quite a spectacle."
But in 1990 they were gone.
The golden toad was the first species when climate change has been identified as a key driver of extinction.
Its fate could be just the beginning.
For years, researchers have warned that the world faces both a climate and a biodiversity crisis. Increasingly, they are connected.
Even if warming is capped at the ambitious target of 1.5 degrees Celsius above pre-industrial levels, the UN's Intergovernmental Panel on Climate Change says nearly one in 10 of all species face extinction.
The golden toad was only found in Monteverde's highland forest. So when trouble hit, the species was wiped out.
"It was pretty clear about 99 percent of the population declined within a single year," says Pounds.
Climate change was barely on the research radar when Pounds arrived in Costa Rica in the early 1980s to study amphibians. But global warming was beginning to take its toll.
After the disappearance of the golden toad, the Monteverde harlequin frog and others, researchers found not only the signature of the periodic El Nino weather phenomenon but also trends linked to changes in climate were at play. The die-offs occurred after unusually warm and dry periods.
Pounds and his colleagues linked the declines to chytridiomycosis infection but concluded that disease "was only the bullet - climate change was pulling the trigger. We hypothesized that climate change and resultant extreme events were somehow loading the dice for these kinds of outbreaks."
It was not an isolated incident.
The expansion of the chytrid fungus globally along with local climate change "is implicated in the extinction of a wide range of tropical amphibians," according to the IPCC.
The fingerprints of global warming have since been seen in other disappearances.
The Bramble Cay melomys, a small rodent living on a low-lying island in the Torres Strait, was last seen in 2009. The only mammal endemic to the Great Barrier Reef, its populations were battered by sea-level rise, increased storm surges and tropical cyclones - all made worse by climate change.
Plants that provided its food fell from 11 species in 1998 to two in 2014. It was recently declared extinct.
Today, climate change is a direct threat to 11,475 species assessed by the International Union for Conservation of Nature. Around 5,775 are at risk of extinction.
The main reason why climate change is increasingly cited as a threat to so many species is that its impacts are becoming more obvious, says Wendy Foden, head of the IUCN's climate change specialist group.
But there is also a growing understanding of the enormous variety of effects. Beyond extreme weather, warming can also cause species to move, change behavior or skew male-female balances. Then there are other human threats like poaching, deforestation, overfishing and pollution.
In 2019, a report by UN biodiversity report experts said one million species could disappear in the coming decades, raising fears the world is entering a sixth era of mass extinction.
Almost 200 countries are currently locked in global biodiversity talks to try to safeguard nature.
But Foden says the threat of climate change means responses will have to go beyond traditional conservation. In some cases people will need to choose which species to save.
As for the golden toad, last year a team from the Monteverde Conservation League launched an expedition to look for it in its historic habitat in the Children's Eternal Rainforest after tantalizing rumours of sightings. It was in vain.
"We haven't completely given up completely," Pounds says. "But with each passing year it looks less likely they're going to reappear."
