![]() ![]() Within the distribution range of Boa sigma, the three islands of the Islas Marías are included: María Madre, María Magdalena and María Cleofas. The northernmost records are from Sonora, where the species can reach altitudes of 1,420 metres (4,659 ft). Distribution and habitat īoa sigma is distributed along the Pacific Coast of Mexico west of the Isthmus of Tehuantepec. Both divergence dates could be explained with the rise of biogeographical barriers. (2016) found the divergence date of these lineages, which they recognized as Boa imperator and Boa sigma, to be around 14 Ma. (2014) identified two lineages of Boa imperator with a divergence date of about 5.2 Ma. Despite this uncertainty, Boa sigma has been widely accepted as a valid species. didn't include samples from the Islas Marías, from where the holotype and the paratypes were collected. However, further research is needed because the genetic study of Card et al. (2016), the name Boa sigma is available for this third species. First, Boa constrictor imperator was elevated to species level, but it was soon recognized that there was another species nested within the new species Boa imperator. ![]() In the 21st century, genetic studies revealed that Boa constrictor is a species complex. The subspecies only included snakes from the Islas Marías, and it did not receive wide recognition instead, it was synonymized with the mainland subspecies Boa constrictor imperator by many authors. Boa sigma has previously been regarded as conspecific with Boa constrictor, and later with Boa imperator however, in 2016, it was suggested on genetic grounds that Boa sigma should be regarded as a separate species.īoa sigma was originally described as Constrictor constrictor sigma by Hobart Muir Smith in 1943. The species is endemic to western Mexico. Constrictor constrictor sigma Smith, 1943īoa sigma, known commonly as the Mexican west coast boa constrictor, is a species of snake in the family Boidae. ![]() The boa first strikes at the prey, grabbing it with its teeth it then proceeds to constrict the prey until death before consuming it whole. However, they do hunt, particularly in regions with a low concentration of suitable prey, and hunting generally occurs at night. Boa constrictors are ambush predators, so often lie in wait for an appropriate prey to come along, when they attack. It makes their eyes appear milky, blue, or opaque so that the snake cannot see very well, causing it to be more defensive than it might be otherwise. Like all snakes, Boa constrictors in a shed cycle are more unpredictable, because of the substance that lubricates between the old skin and the new one. Their bite can be painful, especially from large snakes, but is rarely dangerous to humans. These snakes strike when they perceive a threat. Boa constrictors often occupy the burrows of medium-sized mammals, where they can hide from potential predators. As semi-arboreal snakes, young Boa constrictors may climb into trees and shrubs to forage however, they become mostly terrestrial as they become older and heavier. They are nocturnal, but they may bask during the day when night-time temperatures are too low. Boa constrictors generally live on their own and do not interact with any other snakes unless they want to mate. ![]()
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