Taxonomic Notes
Python bivittatus was recently recognized as a full species (Jacobs et al. 2009), having previously been considered a subspecies of P. molurus. The subspecies P. b. progschai has been erected to describe populations from Sulawesi (Jacobs et al. 2009).
Justification
The Burmese Python is a widely distributed species found throughout Southeast Asia, with evidence of extensive and widespread population declines. Neither generation length nor the scale of declines throughout this snake's global range are well-known, however, it has been listed as Critically Endangered in two major areas within its range due to localized declines greater than 80% over a ten-year period, and exhibits apparently high but unquantified rates of decline throughout its distribution. This snake is conservatively estimated to have declined by at least 30% over the past ten years across its global range as a result of over-harvesting for a variety of uses, to some extent compounded by the effects of habitat loss, and with the drivers of this decline not having ceased. It is therefore listed as Vulnerable.
Geographic Range Information
This species occurs from India, where it has a very disjunct distribution and is known from only two small, isolated areas in the northeast, through Nepal to Indonesia and China (including Hainan). It is absent from Peninsular Malaysia, with a southern limit to its distribution in mainland Asia of Surat Thani in Thailand (M. Auliya and T. Chan-ard pers. comm. September 2011). This snake is absent from Borneo and Sumatra; Borneo has traditionally been included (erroneously) in the species' distribution based on a record of skins from a port in East Kalimantan (M. Auliya pers. comm. September 2011). In Indonesia it has only been confirmed from Java, Nusa Barung, Bali, Sumbawa, and possibly also Lombok, as well as in south Sulawesi (M. Auliya September 2011). It is absent from the Nicobar and Andaman Islands. Whitaker and Captain (2004) report it from Nepal and Bangladesh. As Python molurus, the species has been reported from between 10 and 4,050 m asl.
The species is also introduced and established in the wild in southern Florida, USA via the pet trade (Snow et al. 2007), where it has had detrimental impacts on native fauna, and has recently been blamed for localized declines of up to 99% in encounter rates of several common native mammal species since 2000 in some parts of the Everglades National Park, as well as the apparent loss of introduced rabbits and foxes from these sites (Dorcas et al. 2012).
Population Information
This species has declined across its native range through harvesting for the skin, traditional medicine and pet trade, as well as habitat degradation. Zug et al. (2011) stated that pythons are rare in Myanmar. It is reported to be rare in Cambodia, Lao PDR and Viet Nnam (Q.T. Nguyen and T. Neang pers. comm. August 2011). The Vietnam Red Data Book estimates a decline in this species of more than 80% over 10 years in this country (Dang et al. 2007). This snake is now very rare in mainland China, as it is heavily exploited for food and skins, with population declines estimated at 90% over ten years (Wang and Xie 2009), although it remains common in Hong Kong where it is a protected species. No population data is available for this species in any part of its Indonesian range (M. Auliya pers. comm. September 2011), however, it is now very rare in Indonesia, and is difficult for even traders to find (M. Auliya and D. Iskandar pers. comm. September 2011). It is common in Thailand, where its protected status is well-enforced (T. Chan-ard pers. comm. August 2011). Although rates of decline are not available for many areas of this snake's range, the observation that it is declining throughout its native range and the scale of declines reported from China and Viet Nam justify a conservative estimate of population declines over the past 10 years in excess of 30%, and potentially close to or exceeding 50% over the preceding ten years, with declines ongoing due to heavy exploitation and, to a lesser degree, habitat loss.
Habitat and Ecology Information
The Burmese Python is mostly found in forested areas, including mangrove forests and rainforests, but is also found in grasslands, marshes, streams and rivers, including the Tonle Sap wetland in Cambodia. It is found in wet rocky areas near streams and pools, large rotting logs, large burrows, caves, crevices and old and ruined structures. It has been found inside villages, outside houses, in Cambodia (T. Neang pers. comm. August 2011). It is a good climber and an expert swimmer. It is more nocturnal than diurnal. It feeds on small to large mammals, birds, reptiles and amphibians, preferring to mostly feed on mammals. Breeding occurs in India between December to February after which larger females lay between 80-100 eggs in the months of March and June (Daniel 2002, Whitaker and Captain 2004). Gestation in captivity lasts four months, and eggs have an incubation period of 60 days (Reed and Rodda 2009). In common with almost all snakes, the species reproduces sexually. Exceptionally, however, a female in captivity isolated from males produced viable eggs in five consecutive years; genetic evidence confirmed that the offspring were genetically identical to the mother, making the Burmese Python the only boid snake known to exhibit parthenogenesis (Groot et al. 2003). The snake is unusually cold-tolerant for a python, including subtropical areas of China within its native range, and hibernates to survive the winter (B. Stuart and M. Auliya pers. comm. August 2011).
Observations from Indonesia suggest that this species prefers more arid environments than the Reticulated Python, with which it is sympatric through most of its range. This ecological niche partitioning allows the two species to exist in syntopy, although the Burmese Python is the rarer of the two around human habitations (M. Auliya pers. comm. September 2011).
Captive animals reach sexual maturity at 2-3 years of age with a regular food source (Reed and Rodda 2009), with males maturing earlier than females; generation length in the wild is unknown, but is expected to be at least as long and likely longer.
The introduced subpopulation in Florida thrives in the wet habitat of the Everglades.
Threats Information
This species is under threat due to illegal trade; in China it has been heavily impacted by overexploitation for food and skins, the latter for use both in leather and in traditional musical instruments such as Erheen, Sanxian and hand drums (CITES 2011) and Vietnamese populations are under pressure from a combination of use in food and leather production, export to supply the pet trade, and consumption in snake wine. Similar pressures are presumed to account for the rarity of this species throughout the remainder of its range, for which no quantitative data is available. The subspecies Python b. progschai, which has a restricted range in southern Sulawesi, is of some interest in the commercial international pet trade, and may be vulnerable to exploitation, the type specimen having been recorded in a trader's collection (M. Auliya pers. comm. September 2011, Jacobs et al. 2009). Despite its designation as a protected species in this country, populations in China exhibit no evidence of recovery, and illegal harvesting is ongoing (M. Lau pers. comm. September 2011).
Habitat degradation through slash and burn agriculture in upland areas (Q.T. Nguyen pers. comm. August 2011) may pose a risk by eliminating this snake's prey and making it more vulnerable to exploitation by humans (T. Neang pers. comm. August 2011).
Ironically, this is an invasive species that is firmly established in southern Florida, USA, and poses a threat to the ecosystem there by consuming native wildlife (Snow et al. 2007, Dorcas et al. 2012).
Use and Trade Information
This large constrictor is harvested for food, skin for use in the leather industry, medicinal purposes, and the pet trade. It is known to be used in snake wine in Viet Nam, but in small numbers, with 13 individuals recorded in one recent study (Somaweera and Somaweera 2010). The species is commercially bred in Viet Nam and China, however, production systems vary and Vietnamese operations are reliant on breeding wild-caught individuals, while Chinese systems also breed subsequent captive generations and so are not reliant on a regular wild source (M. Auliya pers. comm. March 2012). Trade in this species is illegal in much of its range due to national protection, however, the species is illegally imported into China and source populations for this trade cannot be traced (M. Lau pers. comm. September 2011). The species is kept by collectors and as pets in much of its range (M. Auliya pers. comm. September 2011). Despite public concerns about the introduction of pythons to the Florida Everglades and their low commercial value, thousands are still imported into the United States from Viet Nam as pets (M. Auliya pers. comm. September 2011). The species is also still imported to Europe. China has recently developed a market for low-quality snake skins, largely supplied from west Malaysia, and pythons may also be supplied for this trade.
Conservation Actions Information
Curbing harvesting of this species throughout its range is needed if populations are to persist outside Thailand. The biology of the species is being extensively studied in its introduced range in southern Florida (e.g. Snow et al. 2007, Dorcas et al. 2011, Dorcas et al. 2012) due to probable negative impacts on the ecosystem and fear by the U.S. public, and more is now known about the species in its introduced range than its native range. More research is required on native populations throughout its range, including those in Indonesia, China, Viet Nam and Cambodia, particularly to establish the effects of trade on this python (Q.T. Nguyen pers. comm. August 2011). It is listed on CITES Appendix II. It is a protected species in Viet Nam, China, Thailand and Indonesia, and is known from protected areas (Q.T. Nguyen, M. Lau and M. Auliya pers. comm. September 2011). It is listed as Critically Endangered in the Vietnam Red Data Book (Dang et al. 2007) and in the Chinese national Red List (Wang and Xie 2009).