The golden toad, a strikingly beautiful amphibian, was discovered in 1966 by herpetologist Jay Savage. This unique creature was found exclusively within a small, high-altitude region of Costa Rica. Known for its vibrant appearance, the species quickly became a symbol of the rich biodiversity found in its specialized cloud forest habitat. Its sudden and mysterious disappearance marked a significant event in conservation history.
The Vanishing Act: A Timeline of Disappearance
The golden toad’s presence in the Monteverde Cloud Forest Reserve was regularly observed from its discovery until the late 1980s. Scientists reported population sizes of around 1,500 adult toads during their breeding season, particularly in April to July 1987. The last documented breeding occurred in April and May of that year, followed by a dramatic decline to only 10 or 11 individuals spotted in 1988. The very last confirmed sighting of a single male golden toad took place on May 15, 1989. Despite extensive searches, no further golden toads were found, and the International Union for Conservation of Nature (IUCN) officially declared the species extinct in 2004.
The Golden Toad’s Unique Characteristics
The golden toad (Incilius periglenes) exhibited a notable difference in appearance between males and females. Male golden toads were distinguished by their bright, iridescent orange-gold coloration and smooth, shiny skin, typically measuring 39 to 48 millimeters. Female golden toads presented a distinct contrast, with dark olive to black bodies adorned with scarlet spots edged in yellow, and were generally larger, ranging from 42 to 56 millimeters. This species was endemic to a small area of approximately 4 square kilometers within the Monteverde Cloud Forest Reserve in Costa Rica, at an elevation of about 1,500 to 1,620 meters. Its breeding habits were highly specialized, involving an “explosive” period from March to June during heavy rains, with males congregating in large numbers around shallow pools where females laid around 200 to 400 eggs.
Unraveling the Mystery: Suspected Causes of Extinction
The extinction of the golden toad remains a complex issue, with scientists pointing to a combination of factors rather than a single cause. A primary suspect is chytridiomycosis, a disease caused by the chytrid fungus, Batrachochytrium dendrobatidis (Bd), which poses a widespread threat to amphibians globally. This fungus attacks the skin of amphibians, thickening it and preventing proper absorption of water and salts, ultimately leading to suffocation.
Changes in local climate patterns are also strongly implicated in the golden toad’s decline. Altered rainfall, increased temperatures, and prolonged droughts, particularly a severe neotropical drought in 1987-1988 linked to El Niño events, may have stressed the cloud forest ecosystem. Such changes could have directly impacted the toad’s sensitive habitat and disrupted its breeding cycles by causing crucial breeding pools to dry prematurely. Scientists propose that the golden toad’s demise resulted from synergistic effects, where these factors interacted to amplify their negative impact. Climate shifts might have made the toads more susceptible to the chytrid fungus. While chytrid fungus and climate change are considered the main drivers, other factors like pollution, habitat degradation, and increased ultraviolet radiation have also been considered.