The Burmese python ( Python bivittatus ) is a large constrictor snake native to southern and Southeast Asia. Known for its exceptional size and adaptability, this apex predator plays a significant role in its native ecosystems and, more controversially, in its introduced range in southern Florida. This article explores the diet of the Burmese python, examining its feeding habits in both its natural habitat and as an invasive species.
Native Habitat and Distribution
Burmese pythons inhabit a variety of environments, including mangrove forests, rainforests, swamps, grasslands, rivers, and rocky areas. Their native range extends from Nepal, Bangladesh, northeastern India, and Myanmar (Burma) eastward to southern China and southward to Vietnam, Laos, Cambodia, and Thailand north of the Isthmus of Kra, as well as the islands of Java, Bali, Sumbawa, and Sulawesi.
Physical Characteristics
Burmese pythons are among the longest snakes in the world, with adults typically growing to between 3 and 5 meters (10 and 16 feet) in length and weighing as much as 90.7 kg (200 pounds). The largest confirmed specimens have measured 5.8 meters (19 feet) long and 97.5 kg (215 pounds), with unconfirmed reports of even larger individuals. Their skin features large dark brown patches against a cream or dark tan background, providing cryptic coloration for camouflage.
Apex Predator Diet
As apex predators, Burmese pythons consume a wide variety of prey. Their diet primarily consists of birds and mammals, but also includes amphibians and reptiles. They are opportunistic feeders. When young, they spend equal time on the ground and in trees.
Hunting Strategy
The Burmese python is a sit-and-wait predator, remaining motionless until prey is within striking distance. They rely on chemical receptors in their tongues and heat-sensors along their jaws to stalk prey, as their eyesight is poor. Once the prey is close enough, the snake strikes and holds it with its powerful jaws and sharp, rearward-pointing teeth.
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Constriction and Suffocation
After capturing its quarry, the Burmese python coils its body around the victim, squeezing tighter with each exhale until the animal suffocates. This method of killing is known as constriction.
Swallowing Prey Whole
Stretchy ligaments in their jaws allow them to swallow animals up to five times as wide as their head! The python then swallows its prey whole.
Dietary Preferences
While they prefer small mammals such as rodents, rabbits, and raccoons, Burmese pythons are capable of consuming larger prey, including deer, pigs, goats, alligators, and domesticated birds such as poultry.
Invasive Species in Florida
The Burmese python has established a significant population in southern Florida, where it is considered an invasive species.
Establishment and Spread
It is believed that the Burmese python population in Florida originated from exotic pets released into the wild, starting in the 1980s. Additional snakes were released after Hurricane Andrew in 1992 destroyed a reptile warehouse. By 2000, breeding populations had been established, and by 2010, the snake was challenging the American alligator for dominance of southern Florida’s wetlands.
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Impact on Native Wildlife
By 2012, Burmese pythons had become significant predators in the area, causing substantial declines in native mammal populations. In the Everglades, deer, bobcat, raccoon, and opossum populations decreased by 87 percent or more, while foxes and rabbits were effectively wiped out. Road surveys between 2003 and 2011 indicated an 87.3% decrease in bobcat populations, and in some areas rabbits have not been detected at all. Bird and coyote populations may be threatened, as well as the already-rare Florida panther.
Dietary Adaptations in Florida
In their invasive range, pythons also eat birds and occasionally other reptiles. Unlike their native South Asian counterparts who spend long periods fasting due to seasonal variation in prey availability, pythons in Florida feed year-round due to the constant availability of food.
International Food Preferences
Voracious Burmese pythons in southern Florida truly have a taste for international food. Invasive Burmese pythons ( Python molarus bivittatus ) have spread rapidly through parts of southern Florida where the temperature is suitable. But feathers often pass through their systems relatively intact.
Isotope Analysis of Feces
Because of this, Davis saw an opportunity to use isotope analysis on feathers left behind in Burmese python feces. Isotopes in carbon, nitrogen and other elements leave a signature that can reveal information about birds, like where they fed in recent weeks. Davis and her colleagues wanted to use this information to find out whether the species that the pythons were eating were local, or if their prey came from farther afield.
Bird Species Identified
Ongoing analysis there has identified 58 different bird species remains that came from the digestive tracts of Burmese pythons. While most of these were Florida birds, Davis was surprised to find 14 different species of nonpermanent residents. These included some closer neighbors that are residents of northern Florida, as well as birds from much farther north. Two individuals, one sora ( Porzana Carolina ) and one American redstart ( Setophaga ruticilla ), came all the way from Canada.
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Implications for Wildlife Management
Davis said this study shows that while wildlife managers think of Burmese pythons as a southern Florida problem, it’s really much larger due to the importance of the area for bird migration. “It’s the first study that shows that this problem goes beyond state borders and even national borders,” Davis said.
Mercury Contamination
Some Burmese pythons removed from the Everglades that have been tested for mercury levels have contained amounts of mercury considered too high for human consumption. Though it is not illegal to eat python meat, the Florida Department of Health recently finalized a consumption advisory for Burmese pythons found in Florida, advising “Do Not Consume Python” due to the high levels of mercury found in python meat.
Digestive Physiology
The digestive response of Burmese pythons to such large prey has made them a model species for digestive physiology.
Fasting and Feeding Cycles
Its sit-and-wait hunting style is characterized by long fasting periods in between meals, with Burmese pythons typically feeding every month or two, but sometimes fasting for as long as 18 months. As digestive tissues are energetically costly to maintain, they are downregulated during fasting periods to conserve energy when they are not in use.
Physiological Changes During Digestion
A fasting python has a reduced stomach volume and acidity, reduced intestinal mass, and a 'normal' heart volume. After ingesting prey, the entire digestive system undergoes a massive re-modelling, with rapid hypertrophy of the intestines, production of stomach acid, and a 40% increase in mass of the ventricle of the heart to fuel the digestive process. During digestion, the snake's oxygen consumption rises drastically as well, increasing with meal size by 17 to 40 times its resting rate. This dramatic increase is a result of the energetic cost of restarting many aspects of the digestive system, from rebuilding the stomach and small intestine to producing hydrochloric acid to be secreted in the stomach. Hydrochloric acid production is a significant component of the energetic cost of digestion, as digesting whole prey items requires the animal to be broken down without the use of teeth, either for chewing or tearing into smaller pieces.
Conservation Status and Threats
The International Union for Conservation of Nature and Natural Resources (IUCN) lists the Burmese python as a vulnerable species. Despite its wide distribution and the establishment of a large population in Florida, Burmese python numbers have fallen throughout the early 21st century.
Threats in Native Range
In its native range, the Burmese python is threatened by harvesting for food, its hide (used to make leather garments and drums), and the pet trade. Habitat loss, specifically the conversion of forest and marshland to agricultural land, also reduces prey populations and the snake’s ability to hide from hunters.
Conservation Efforts
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. The species is protected in Hong Kong, Thailand, Vietnam, China, and Indonesia.
Management in Florida
Python control and management is a high priority for the FWC. The agency and partners are taking a multifaceted approach, focusing on removal and community engagement. Burmese pythons cannot be kept as pets in Florida. Through the Exotic Pet Amnesty Program, pet owners who are either unable to care for their nonnative pets or who no longer wish to keep them can surrender them with no questions asked and without penalties, regardless of whether those pets are kept legally or illegally.