The Burmese python (Python bivittatus ) is one of the largest species of snakes. It is native to a large area of Southeast Asia and is listed as Vulnerable on the IUCN Red List.[1] Until 2009, it was considered a subspecies of the Indian python, but is now recognized as a distinct species.[3] It is an invasive species in Florida as a result of the pet trade.[4]
The Burmese python is a dark-colored non-venomous snake with many brown blotches bordered by black down the back. In the wild, Burmese pythons typically grow to 5 m (16 ft),[5][6] while specimens of more than 7 m (23 ft) are unconfirmed.[7] This species is sexually dimorphic in size; females average only slightly longer, but are considerably heavier and bulkier than the males. For example, length-weight comparisons in captive Burmese pythons for individual females have shown: at 3.47 m (11 ft 5 in) length, a specimen weighed 29 kg (64 lb), a specimen of just over 4 m (13 ft) weighed 36 kg (79 lb), a specimen of 4.5 m (15 ft) weighed 40 kg (88 lb), and a specimen of 5 m (16 ft) weighed 75 kg (165 lb). In comparison, length-weight comparisons for males found: a specimen of 2.8 m (9 ft 2 in) weighed 12 kg (26 lb), 2.97 m (9 ft 9 in) weighed 14.5 kg (32 lb), a specimen of 3 m (9.8 ft) weighed 7 kg (15 lb), and a specimen of 3.05 m (10.0 ft) weighed 18.5 kg (41 lb).[8][9][10][11][12] In general, individuals over 5 m (16 ft) are rare.[13] The record for maximum length of a Burmese python is 5.79 m (19 ft 0 in) and was caught 10 July 2023 in South Florida’s Big Cypress National Preserve.[14] Widely published data of specimens reported to have been several feet longer are not verified.[7] At her death, a Burmese named “Baby” was the heaviest snake recorded in the world at the time at 182.8 kg (403 lb),[7] much heavier than any wild snake ever measured.[15] Her length was measured at 5.74 m (18 ft 10 in) circa 1999.[7] The minimum size for adults is 2.35 m (7 ft 9 in).[16] Dwarf forms occur in Java, Bali, and Sulawesi, with an average length of 2 m (6 ft 7 in) in Bali,[17] and a maximum of 2.5 m (8 ft 2 in) on Sulawesi.[18] Wild individuals average 3.7 m (12 ft) long,[5][6] but have been known to reach 5.79 m (19 ft 0 in).[14]
Diseases
In both their native and invasive range they suffer from Raillietiella orientalis (a pentastome parasitic disease).[19]
The Burmese python occurs throughout Southern and Southeast Asia, including eastern India, southeastern Nepal, western Bhutan, southeastern Bangladesh, Myanmar, Thailand, Laos, Cambodia, Vietnam, northern continental Malaysia, and southern China in Fujian, Jiangxi, Guangdong, Hainan, Guangxi, and Yunnan.[20] It also occurs in Hong Kong, and in Indonesia on Java, southern Sulawesi, Bali, and Sumbawa.[21] It has also been reported in Kinmen.[22]
It is an excellent swimmer and needs a permanent source of water. It lives in grasslands, marshes, swamps, rocky foothills, woodlands, river valleys, and jungles with open clearings. It is a good climber and has a prehensile tail. It can stay in water for 30 minutes but mostly stays on land.
stress, with winter freezes resulting in mortality rates of up to 90%. Genomic data suggests natural selection on these populations favors increased thermal tolerance as a result of these high-mortality freezes.[39]
They have carried Raillietiella orientalis, a pentastome parasitic disease, with them from Southeast Asia. Other reptiles in Florida have become infested, and the parasite appears to have become endemic.[19]
In April 2019, researchers captured and killed a large Burmese python in Florida’s Big Cypress National Preserve. It was more than 5.2 m (17 ft) long, weighed 64 kg (140 lb), and contained 73 developing eggs.[40] In December 2021, a Burmese python was captured in Florida that weighed 98 kg (215 lb) and had a length of 5.5 m (18 ft); it contained a record 122 developing eggs.[41] In July 2023, local hunters captured and killed a 5.8 m (19 ft) long Burmese python that weighed 57 kg (125 lb) in Florida’s Big Cypress National Preserve.[14]
Burmese pythons are mainly nocturnal rainforest dwellers.[42] When young, they are equally at home on the ground and in trees, but as they gain girth, they tend to restrict most of their movements to the ground. They are also excellent swimmers, being able to stay submerged for up to half an hour. Burmese pythons spend the majority of their time hidden in the underbrush. In the northern parts of its range, the Burmese python may brumate for some months during the cold season in a hollow tree, a hole in the riverbank, or under rocks. Brumation[43] is biologically distinct from hibernation. While the behavior has similar benefits, allowing organisms to endure the winter without moving, it also involves the preparation of both male and female reproductive organs for the upcoming breeding season. The Florida population also goes through brumation.[44]
They tend to be solitary and are usually found in pairs only when mating. Burmese pythons breed in the early spring, with females laying clutches of 12–36 eggs in March or April. They remain with the eggs until they hatch, wrapping around them and twitching their muscles in such a way as to raise the ambient temperature around the eggs by several degrees. Once the hatchlings use their egg tooth to cut their way out of their eggs, no further maternal care is given. The newly hatched babies often remain inside their eggs until they are ready to complete their first shedding of skin, after which they hunt for their first meal.[45]
Parthenogenesis
The Burmese python is able to reproduce asexually when in captivity.[12] Offspring are clones of their mother and reproduction appears to be by a parthenogenetic mechanism that involves a modification of the meiotic process.[12]
The Burmese python is listed on CITES Appendix II.[1] It has been listed as vulnerable on the IUCN Red List since 2012, as the wild population is estimated to have declined by at least 30% in the first decade of the 21st century due to habitat loss and over-harvesting.[1]
To maintain Burmese python populations, the IUCN recommends increased conservation legislation and enforcement at the national and international levels to reduce harvesting across the snake’s native range. The IUCN also recommends increased research into its population ecology and threats. In Hong Kong, it is a protected species under Wild Animals Protection Ordinance Cap 170. It is also protected in Thailand, Vietnam, China, and Indonesia. However, it is still common only in Hong Kong and Thailand, with rare to very rare statuses in the rest of its range
Burmese pythons are often sold as pets, and are made popular by their attractive coloration and apparently easy-going nature. However, they have a rapid growth rate, and can exceed 2.1 m (6 ft 11 in) in length in a year if power fed. However this may cause health issues in the future. By age four, they will have reached their adult size, though they continue growing very slowly throughout their lives, which may exceed 20 years.
Although the species has a reputation for docility, they are very powerful animals – capable of inflicting severe bites and even killing by constriction.[52][53][54][55][56][57] They also consume large amounts of food, and due to their size, require large, often custom-built, secure enclosures. As a result, some are released into the wild, and become invasive species that devastate the environment. For this reason, some jurisdictions (including Florida, due to the python invasion in the Everglades[58]) have placed restrictions on the keeping of Burmese pythons as pets. Violators could be imprisoned for more than seven years or fined $500,000 if convicted.
Burmese pythons are opportunistic feeders;[59] they eat almost any time food is offered, and often act hungry even when they have recently eaten. As a result, they are often overfed, causing obesity-related problems to be common in captive Burmese pythons.[citation needed]
Like the much smaller ball python, Burmese pythons are known to be easygoing or timid creatures, which means that if cared for properly, they can easily adjust to living near humans.[60]
Handling
Although pythons are typically afraid of people due to their great stature, and generally avoid them, special care is still required when handling them. Given their adult strength, multiple handlers (up to one person per meter of snake) are usually recommended.[61] Some jurisdictions require owners to hold special licenses, and as with any wild animal being kept in captivity, treating them with the respect an animal of this size commands is important.[62]
Variations
The Burmese python is frequently captive-bred for color, pattern, and more recently, size. Its amelanistic form is especially popular and is the most widely available morph. This morph is white with patterns in butterscotch yellow and burnt orange. Also, “labyrinth” specimens with maze-like patterns, khaki-colored “green”, and “granite” with many small angular spots are available. Breeders have recently begun working with an island lineage of Burmese pythons. Early reports indicate that these dwarf Burmese pythons have slightly different coloring and pattern from their mainland relatives and do not grow much over 2.1 m (6 ft 11 in) in length. One of the most sought-after of these variations is the leucistic Burmese. This particular variety is very rare, being entirely bright white with no pattern and blue eyes, and has only in 2008/2009 been reproduced in captivity as the homozygous form (referred to as “super” by reptile keepers) of the co-dominant hypomelanistic trait. The caramel Burmese python has a caramel-colored pattern with “milk-chocolate” eyes.