The Green Anaconda – Natural History of the World’s Largest Snake – Part 2

Hello, Frank Indiviglio here.  In Part 1 of this article we examined the natural history of this heaviest and possibly longest of all snakes.  The Green Anaconda (Eunectes murinus) has generated a great many stories – through field research, I’ve had several opportunities to ferret out some interesting details behind these (please see article referenced below).  Today we’ll take a look at the astonishing array of creatures it is known to consume.

A Most Varied Diet

Green Anacondas take a wider range of animals than most, if not all, other snakes.  Documented prey species include young tapir, capybara, sheep, dogs, domestic pigs, white-tailed deer, agoutis, peccaries, turtles, tegus, caimans, other anacondas, frogs, herons, ducks, fishes and, possibly, people.  Anacondas are constrictors – prey is killed by suffocation (lung compression) and heart failure (pressure on the heart, veins and arteries).

While conducting field research in Venezuela, I several times encountered Anacondas consuming large prey items, including a 60 pound white-tailed deer, a 5-foot-long spectacled caiman and a large side-necked turtle. 

An (happily unsuccessful!) attack on a co-worker was almost certainly a feeding response and not defense-oriented.

Dangers from Predators and Prey

Young Anacondas are eaten by wading birds, tegus, caimans, turtles, other Anacondas and similarly-sized predators; there are reports of jaguars and pumas attacking sub-adult animals. 

Large adults have no known predators other than people, but often bear injuries received in overcoming caiman, capybaras, deer and other large animals.  Most of the large Anacondas that I handled bore wounds and evidence of broken ribs.  I also noted what appeared to be bite marks from piranha on several snakes…and 1 person!  One Anaconda was found with mouth wounds sustained while attempting to consume a side-necked turtle.  This snake later died, possibly due to an infection.

Zoo Diets

Typical food items include rats, guinea pigs, rabbits, ducks, chickens, fish and pigs of 15-25 pounds in weight. 

Captive Anacondas sometimes exhibit very distinct food preferences (often duck), and will refuse all but their favored prey.  I cared for one individual that would eat wild-caught but not lab-raised Norway rats and another that refused all but muskrats.   

People as Snake Prey

Wild Green Anacondas have, as I observed, attacked people and actual predation is suspected.  The snakes reliably known to have consumed people are the Reticulated Python, Python reticulatus, the African Rock Python, Python sebae, and, possibly, the Burmese Python, Python molurus.  I’m aware of several instances in which captive Burmese Pythons have killed their owners.

Giant Meals for Giants

The largest prey item consumed by a captive snake seems to be a 130 pound impala antelope fed to a Reticulated Python.  The largest meal taken by an Anaconda appears to be a 100 pound peccary consumed by a 26’9” specimen in French Guiana. 

The 60 pound deer consumed by an Anaconda that I captured in Venezuela likely represents the upper size limit of prey for specimens of 17 feet or so in length.  A 22-foot-long wild-caught Reticulated Python under my care regularly consumed 30-40 pound pigs, but I preferred offering animals in the 20 pound range.

Further Reading

You can read more about the research mentioned above in these articles:

Hunting Anacondas in the Venezuelan Llanos.

Big Snake Meals – records of large and unusual meals.

Field research reports and summaries.

Please write in with your questions and comments. 

Thanks, until next time,

Frank Indiviglio

Anaconda eating Capybara display Frankfurt Museum image referenced from wikipedia and originally posted by EvaK
Green Anaconda image referenced from wikipedia and originally posted by LtShears

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