The Golden lancehead (Bothrops insularis) is a highly venomous pit viper species native to Brazil. The species is named for the light yellowish-brown color of its underside and for its head shape that is characteristic of the genus Bothrops. It is one of the most venomous snakes in Latin America.
The color pattern of this snake consists of a pale yellowish-brown ground color, overlaid with a series of dorsal blotches that may be triangular or quadrangular, broad or narrow, and alternating or opposite along the dorsal median. In captivity, this yellowish color often becomes darker, which may be the result of poor circulation caused by ineffective thermoregulation. A banded pattern results when the pattern is opposite. The head lacks a well-defined post-orbital stripe. The belly is a uniform pale yellow or cream. The Golden lancehead also has a long tail, which is most likely an adaptation to help the snake maneuver through the trees and to eat larger prey like birds from a younger age.
Golden lanceheads can be both terrestrial or arboreal, even though they do not have a truly prehensile tail. They prefer to spend time singly and can usually be found either in the trees hunting for prey or seeking shelter among leaf litter or in rock crevices, especially during unfavorable weather or after having just ingested their prey.
Because of the isolated habitat of the Golden lancehead, and the lack of mammal prey species, the venom of this species has evolved to be adapted to the prey species of the island, primarily native ectotherms, arthropods, and migrating birds. As a result, their venom is more potent towards these groups than mammals and becomes more potent as the snake matures. Chemical analysis of the venom of the Golden lancehead suggests that it is five times as potent as that of B. jararaca and is the fastest acting venom in the genus Bothrops. Because the Golden lancehead is only found in an area uninhabited by humans, there has never been an official report of a human being bitten by one, but other lanceheads are responsible for more human mortality than any other group of snakes in either North or South America. Ludwig Trutnau reports four human envenomations, three of which were fatal. The effects of envenomations by Golden lanceheads include swelling, local pain, nausea and vomiting, blood blisters, bruising, blood in the vomit and urine, intestinal bleeding, kidney failure, hemorrhage in the brain, and severe necrosis of muscular tissue.
Golden lanceheads are carnivores and their diet consists mostly of perching birds. However, they have been reported to eat lizards, and even resort to cannibalism. Newborn and juvenile Golden lanceheads prey primarily upon invertebrates.
Golden lanceheads breed during August and September. Like most vipers, they give birth to live young. The average size for a litter is usually 6 newborns.
The main threat to this species is the destruction of its native habitat. Because the island on which the Golden lancehead is found is so small, it can only support a small population, which means that the range between the number of snakes required for the population to survive and the maximum number of snakes the island can support may be small; this makes the species especially sensitive to any other problems. Also, because the island of Woody Grande is the only place where Golden lanceheads are found in the wild if that population is wiped out, then the species will be extinct in the wild.
The IUCN Red List and other sources don’t provide the number of the Golden lancehead total population size. Currently, this species is classified as Critically Endangers (CR) on the IUCN Red List but its numbers today are stable.