Home | Amphibians | An Appetite for Cobras: Huge Bullfrog Meals

An Appetite for Cobras: Huge Bullfrog Meals

Pixie Frog
Those who keep or observe frogs soon learn of their prodigious appetites. Surely the champion Anuran eater must be the African bullfrog, Pyxicephalus adspersus. Native to southern Africa, this brute is a popular pet, and with good reason – captive longevity is said to approach 50 years. Two animals that I know of, kept in separate enclosures by the same person, both expired at age 21, in the same week.

The most memorable “frog-eating footage” I’ve seen focused on African bullfrogs in the Etosha Pan, northern Namibia. One enormous animal swallowed a centipede of at least 10 inches in length, which bit the frog numerous times on the way down. Another frog latched onto an emperor scorpion, which also did its best to make itself a “memorable” meal. But a note I read in an African nature journal tops all – a huge male frog burrowed into an outdoor cage at a South African snake park and was, when discovered, in the process of swallowing his 17th baby spitting cobra!

All of this eating results, as you might imagine, in frogs of impressive proportions – a male at the Fort Worth Zoo measured 10 inches from snout to vent and 9 ¾ inches around – a near perfect circle! His weight surely topped 5 pounds, but I do not have the exact figure.
American Bullfrog
Our own American bullfrog, Rana (Lithobates) catesbeianus, offers its African cousin some competition. While working at the Bronx Zoo, it became my habit to toss crickets to the bullfrogs that had colonized a small artificial pond. The frogs became bold in time, and visitors enjoyed the show. On one occasion a bullfrog’s leap for food brought it directly in front of another. The larger animal grabbed the smaller, who was fully three quarters his size and, in front of 50 or so second-graders, proceeded to jam the squirming neighbor down his massive gullet. I observed this fellow thereafter – his noticeably distended abdomen flattened out in two days, after which he again gobbled crickets with enthusiasm!


Male African bullfrogs are diligent parents – they defend the eggs and dig channels to bring water to their tadpoles. You can learn more at:


  1. avatar

    Dear frank

    This article is extremly intresting to me. For i live near a swamp where there are large american bullfrogs and i watch them from the deck with a good pair of binoculars and i’ve seen them down there doing some prity intresting things i’ve seen a many of them stalking birds and reminence of feathers near his domain and i witness alot of basking and terratory display unfortinitly the biggest bullfrog on my swamp that i know of died. i found it dead in its teratory with no wounds so i decided to incest it and found a partly digest rough skinned newt! which has enough posion to kill 3 men but only if injested i then did my reaseach and learned that bullfrogs will sometimes get ahold of these but ushaly regurgitate these but those who dont will die 15-30min in there tracks.

    • avatar

      Very interesting observation…thanks, Cody! I imagine your on the west coast, due to the rough skinned newt reference. Bullfrogs are introduced there, and apparently do not instinctively avoid toxic prey. Here in the east, where they are native, they are not known to prey upon marbled salamanders and others. Same re marine toads in Australia…monitors, snakes eat them, and often die; predators within their range won’t touch them…I’ve kept anacondas with marine toads for years. Some learning involved also...please see this article.. Take notes…watching one area long term is the best way to uncover interesting info, never know what you’ll find out! Best, Frank

  2. avatar

    Yes frank

    I live in grays harbor washington. Our native frog speices are quite afew tree frogs and chorus frogs allso red leged frogs. The bullfrog is highly intresting to me and you may enjoy this. Here its consiterd a real monster and it is invadeing…But i think they are a frog who is good at what they do for i have witnessed acts of canablism among red leged frogs. The main reason why they are so intesting is here the water is verry cold most tadpoles have to stay in the water for up to 2-3 years! insted of just 3-6months my swamp behind my house drys up every year and the verry end of summer for about amonth or two till first rains and i still have these giant bullfrogs here and not so giant ones. I’ve noticed after the swamp drys up they will stay and take advantage of low water hunting but being verry spooked scattering into the woods at all directions appon anywhere near arrival. then a week after that you wonder where they go? you take a stroll down to the stream and a bullfrog jumps in with its infamous squeek. and can live on the banks of the 32-36deg water stream i do belive its prity cold here. and creeks don’t worm up nomatter how sunny like ponds. but these bullfrogs migrate during breeding season maby 3 miles to a big slough like area and i belive thats where they lay there tadpoles that move down to my swamp and then hybernate in the mud for the winter! next spring around april ill be spotlighting aqutaic insects and mudminnows “for my pumpkinseed and largemouth bass at the time” and these giant bullfrogs come outa nowhere right outa the mud. I like to go out there at night and spot light them i learn that one big guy tends to stay in the same spot so this way i can identify large indviduals this way.

    frog lover cody!

    • avatar

      Great stuff, Cody.. amazing how they can adapt to completely foreign environment,s change basic behaviors. There’s some interest in them, as they are established in many countries…I’ll save this and let you know if I come across someone working with them; Would be great if you could document 3 year tads..I haven’t checked, but 2 years is the longest I recall. Best, Frank

  3. avatar

    It is and i’ve done similar studys but with spedup growth rates takeing 1-2year large coldwater tadpoles from a cold lake makeing the largest bullfrog hatchling possible. I can’t recall where but i hurd the longer the tadpole stays a tadpole the healther and bigger the frog will be as a polywog and youngling. takeing these tadpoles that had been in the lake 1-2years with no legs still and i want to say 3-5inc. 2weeks in a 29gal aquarium heated too 74-80deg and they were fullblown frogs i found that the polywog stage took about 4days at that heat. But whats intresting and still going on to me is my 2nd bullfrog i have in the tank is still in polywog stage while the other one is 7days old as a frog and the two are insepartaeible. Well the one frog does its own thing on land and the polywog loves to follow it and sit there even tho it has full tail and just now in the past 10hours can lift it’s head. Any ideas on why this is? its like it thinks its a frog allredy it even climed up on the bark my youngling likes to climb on verry weird because that frog never left the water in the same enviorment till days after frog then still lingerd in shallows.


    • avatar

      Thanks, Cody,

      There is some evidence that several amphib species will remain in the larval stage as long as possible, so as to transform at a larger size, etc. temperature can speed growth to a point, but can also be a negative, depending on the species (many become susceptible to bacterial/fungal attack as temps rise); rising temps 9and probably changes in pH, etc) can also signal falling water levels, and speed transformation…some tiger salamander larvae actually develop different teeth and jaw structures in very low water; this allows them to eat other larvae as opposed to inverts, speeding their development…and they preferentially eat non-relatives! So, lots to learn…keep at it.

      metamorphs may stay together in order to confuse predators,,,as they scramble away, it’s hard to pick one out; also congregate near food, shelters, etc. Re development, there is a good deal of genetic variability, it seems,…this may be one reason why some species are good at adapting to new environments…many new gene combinations/behaviors are possible, and one may work, best, Frank

About Frank Indiviglio

Read other posts by

Being born with a deep interest in animals might seem unfortunate for a native Bronxite , but my family encouraged my interest and the menagerie that sprung from it. Jobs with pet stores and importers had me caring for a fantastic assortment of reptiles and amphibians. After a detour as a lawyer, I was hired as a Bronx Zoo animal keeper and was soon caring for gharials, goliath frogs, king cobras and everything in-between. Research has taken me in pursuit of anacondas, Orinoco crocodiles and other animals in locales ranging from Venezuela’s llanos to Tortuguero’s beaches. Now, after 20+ years with the Bronx Zoo, I am a consultant for several zoos and museums. I have spent time in Japan, and often exchange ideas with zoologists there. I have written books on salamanders, geckos and other “herps”, discussed reptile-keeping on television and presented papers at conferences. A Master’s Degree in biology has led to teaching opportunities. My work puts me in contact with thousands of hobbyists keeping an array of pets. Without fail, I have learned much from them and hope, dear readers, that you will be generous in sharing your thoughts on this blog and web site. For a complete biography of my experience click here.
Scroll To Top