Bushmaster
Species Description
Bushmasters are one of the largest vipers in the world. They are the longest vipers; while Gabon Vipers and Eastern Diamondback Rattlesnakes are the heaviest vipers in the world. There have been reports of bushmasters measuring up to 14 feet but it is more likely that 12 feet is the maximum length. Bushmasters are sexually dimorphic in size with males reaching larger sizes.
Photo: Brian Eisele Bushmasters are incredibly beautiful snakes with a pinkish tan, orangish tan, reddish brown or yellowish color with a series of dark markings down the back. Younger snakes usually have a darker ground color and lighter marking on their back relative to adult animals. Overall, there is a great deal of variation in color within and among bushmaster species. However, there are some color differences such as melanocephal; having a very dark head. In addition, bushmasters found in Central America often have wider heads with blunter snouts while bushmasters in the Amazon, especially those in the Guiana Shield have a narrower lancehead shape to the head. The middorsal scales or scales that run down the middle of the back have raised knoblike keels. The keels get smaller as you go towards the tail. Bushmaster’s fangs can be over two inches long and rival the Gabon Viper for longest fang length in snakes.
Taxonomy
The bushmaster was first described by F. M. Daudin in 1803 and the genus name came from one of the Three Fates in Greek Mythology. Lachesis is a goddess that measures the thread of life or how long each person will live. Historically, the genus was thought to be a single species, muta, with four subspecies but subsequent morphological and genetic studies show that there are four species (acrochorda, melanocephala, muta, and stenophrys) with one of the species containing two subspecies (muta muta and muta rhombeata).
Distribution
Bushmasters occur entirely within the New World and specifically within the countries of Bolivia, Brazil, Columbia, Costa Rica, Ecuador, French Guiana, Guyana, Nicaragua, Panama, Peru, Surinam, and Venezuela. The Chocoan Bushmaster (Lachesis acrochorda) occurs on both the Pacific and Atlantic versants of eastern Panama, throughout the valleys of Northwestern Columbia and along the Pacific Coast of Northwest Ecuador. The Black-headed Bushmaster (Lachesis melanocephala) is restricted to the Pacific versant of Costa Rica in the vicinity of the Osa Peninsula. The South America Bushmaster (Lachesis muta) occurs throughout the Amazon Basin and in the coastal Atlantic Forests of Brazil. The Central American Bushmaster (Lachesis stenophrys) occurs in Atlantic lowlands from Nicaragua to Panama. The Black-headed and Chocoan Bushmasters have been found up to 1,600 meters in elevation while the South and Central American species have only been found up to 1,000 meters in elevation.
Habitat
Throughout their range bushmasters are primarily found in undisturbed lowland and pre-montane rainforest. However, in some parts of their range they can be found in dryer regions but always along riparian corridors. Bushmasters can occasionally be found in forests that have been cut for a short time period but they are mostly associated with primary forest.
Movement and Home Range
Almost nothing is known about the movements and home range size of bushmasters except that they are active primarily at night and that they can remain coiled in the same location for almost a month. Bushmasters have also been observed in seasonally flooded forests during the dry season indicating that they may have some form of seasonal migration to uplan forests during the wet season.
Diet
Bushmasters are sit and wait predators that specialize in eating small mammals including rodents and marsupials. They have also been observed to feed on porcupines. Unlike many other vipers that strike and release their prey, bushmasters often strike and hold onto the prey injecting large amounts venom. Juvenile bushmasters have brightly colored tail tips but unlike other vipers with similar tails they have not been observed using their tail to lure prey.
Reproduction
Bushmaster reproduction is fascinating as they are the only species of vipers in the New World that lay eggs. Females have been observed laying between 6 and 20 eggs in old logs or mammal burrows from May through August. The females then protect the nest by coiling around the eggs which can take approximately three months to hatch. There is some evidence that bushmaster eggs need high humidity to successfully hatch and that nesting may correspond with wet seasons.