There really isn’t any other way to put it: Bullfrogs are aggressive and greedy predators.
They have huge mouths and will try to eat any living thing smaller than themselves. If a bullfrog can’t get the whole critter in its mouth in one bite, it uses both hands to stuff it into their maw.
Food items found in their stomachs include crawfish, salamanders, mice, snakes, small turtles, ducklings, snails, insects, fish, tadpoles, smaller frogs and even bats.
Interestingly, most South Louisiana frogs’ stomachs hold crawfish.
Most of the oddball stuff turns up in the stomachs of North Louisiana frogs that live in rivers, streams, lakes and farm ponds.
Bullfrogs are so aggressive they are actually quite easy to catch on fishing lures during the daytime. A frog spotted at the water’s edge is easy pickin’s with a Texas-rigged plastic worm: Expose the whole hook by pushing it through the body of the worm and cast it to land just above the water’s edge about 18 inches to one side of the frog.
When the worm hits the bank, the frog will respond by immediately repositioning its body to face the worm. One twitch of the bait will send the frog into a head-first, mouth-open leap to pounce on the worm.
One scientist called a bullfrog’s strike a “ballistic lunge,” and noted that bullfrogs always jump with their eyes closed.
Even with their eyes closed, they rarely miss. Setting the hook is simple.
Dangling a popping bug in front of a frog with a long fly rod is even more deadly than using a worm, but a fly rod isn’t always handy.
A frog added to an ice chest will chill down nicely, and even one frog is a welcome addition to a plate of fried fish.
Louisiana froggers actually catch two species of frogs rather than one: the American bullfrog (Rana catesbeiana) and the pigfrog (Rana grylio).
Rana means “frog” in Latin. The species name catesbeiana was created by naming the frog for Mark Catesby, a well-known 18th century English naturalist. Grylio is a version of the Latin name for “cricket” or “grasshopper.”
The American bullfrog is found statewide, and because it travels over land with ease will turn up in any and every waterhole — man-made or natural.
The pig frog, sometimes called a “cruk-cruk” because it produces a pig-like grunt, is limited to the state’s freshwater marshes, the Cajun prairie region north of these marshes, as well as all of the Florida Parishes (those parishes found east of the Mississippi River and north of Lake Pontchartrain).
While bullfrogs grow to a body length of 8 inches, pig frogs are smaller, with 6 inches being the maximum.
Pig frogs also have a more-pointed snout than do bullfrogs, and are much more water-loving than bullfrogs. They seldom leave the water to sit on a bank, even when calling during spawning season.
Both species of frogs are generally olive above and lighter below. Bullfrogs from the southern part of the state tend to have more-pronounced darker mottling marks than do those from North Louisiana.
Every year or so a rare “blue frog” is caught in Louisiana. More turquoise than blue, they create quite a stir amongst froggers when one is caught.
Froggers will also notice that some bullfrogs have bright-yellow throats. These are always males, as females have white throats.
The sexes can also be separated by looking at their tympani (the eardrums located immediately behind each eye). The tympani of males are much larger in diameter than their eyes, while female tympani are about the size of their eyes.
Females also grow larger than males.
What bullfrogs are known for, and what makes hunting them productive, is that they gather into groups (called “choruses” by biologists and “spawns” by froggers) for the purpose of spawning.
There, they sing loudly to attract females beginning in March when air temperatures rise above 70 degrees Fahrenheit and extending through the summer. Although to most people the singing all sounds the same — loud, base bellows — scientists have identified at least three different types of calls.
These include territorial calls made as threats to other males, advertisement calls to attract females and encounter calls made right before combat with another male frog.
While to froggers choruses appear to be just a group of randomly assembled frogs, they have a definite structure.
Older males stake out their territory in the center of a chorus, while younger males must settle for the edges. Dominant males that have a territory will sit more erectly on the bank or inflate their bodies to float higher in the water. Both actions more fully display their bright-yellow throats.
Non-territorial males remain in the water, with only their heads showing above the surface.
Some males adopt what scientists call a “satellite male strategy.” These males sit near territorial males, take a submissive posture and make no attempt to challenge the dominant male by intercepting females. They seem to be waiting for territories to become vacant.
Choruses are not permanent or even long-term structures. They frequently break up after a few days and reform in another spot. Individual males will often move from one chorus to another or change territories within a chorus.
When a female shows interest in a particular male, either because of his singing or because of the location of his territory, the male will climb on top of the female’s back, grabbing and holding her behind her forelegs with his own forelegs.
As she lays her eggs (up to 20,000 in a batch), the male releases sperm to fertilize the eggs as they are laid. The egg mass forms a thin, floating sheet 5 to 10 square feet in size, and the eggs hatch in three to five days.
At first, the tadpoles feed by pumping water through their gills and trapping bacteria, algae and microscopic animals on mucous membranes. As they grow they feed more actively with their mouths and use their teeth to rasp food from submerged plants and debris.
They will also actively scavenge dead fish and other animals, and have been known to feed on each other.
Some tadpoles develop into frogs in a few months, while others overwinter as tadpoles.
The transformation is a major anatomical event. First, they grow rear legs. Then, as the front legs begin to develop, their bodies gradually absorb the tails.
As their gills shrink, their bodies develop the nerves and blood supply needed for internal lungs. As the gills disappear, it becomes necessary for the developing frog to come to the water’s surface to breathe.
Bullfrogs can, however, “breathe” through their skins during periods of low temperatures, which is how they overwinter buried in the bottom mud. They do this through a network of large blood vessels that lie just beneath the skin, especially on their backs.
In the wild, bullfrogs are thought to live as long as eight to 10 years, although one frog in captivity was recorded to live to 16 years old.