The bullfrog is a species that threatens the survival of many other species, including other types of frogs and amphibians, due to its ferocity, its voracity and its great adaptive capacities. We are therefore talking about an invasive species These frogs, from North America, are colonizing all kinds of ecosystems without restraint. Any niche in which there is a body of water is a possible target for the generation of impressive bullfrog colonies. Do you want to know why these frogs are so dangerous for the media they reach?
In this sheet of frog species on our site we will talk in detail about the bullfrog, its characteristics, habitat, feeding or reproduction, factors that have played an essential role in its development as an invasive species. Read on to discover it all!
Origin of the bullfrog
The bullfrog is an amphibian of the Ranidae family that comes from the American continent, specifically North America, being typical of southern Canada, eastern Mexico and the entire United States. Even so, in some US states it is considered an invasive species because, for example, it arrived in California at the beginning of the 20th century, quickly becoming a colonizing species which was a tough competition for the local fauna.
These frogs have become an invasive species in many countries throughout the world. This has not happened by chance, because this brutal expansion is due, of course, to the intervention of the human being, since these frogs have been exported to become exotic pets, as well as for consumption as "gourmet" food.
Currently the species is considered an invasive species, one of the most aggressive, in all the countries where colonies of these frogs have formed, being declared as one of the 100 most harmful and destructive invasive species from around the world.
Physical Characteristics of the Bullfrog
The bullfrog reaches a large size, being the largest in North America We highlight its long hind legs, 25 cm. long, which exceed the body itself, which measures about 20 cm. long. These frogs can weigh more than 1 kilogram, measuring in total from about 10 or 17 to even 46 centimeters. A wild bullfrog can live up to 10 years, while in captivity they can live up to 16.
The head of bullfrogs is flat and quite wide, with a fold of skin on both sides of the head, specifically from behind the eyes to the eardrum. It is in this tympanum where we find sexual dimorphism in bullfrogs, since males have larger ones with a dark edge, while the diameter is smaller in females, being the same size as their eyes.
They present Darker spots or specks that the rest of the body disperses throughout their torso, head and extremities. These extremities end in hands and feet that have four fingers, presenting interdigital membranes in their hind legs between all their fingers except the fourth.
Bullfrog Habitat
Bullfrogs are one of the animals with the greatest potential for adaptation, which is why they can be found near almost any body of fresh water, especially those where temperatures are not excessively low. They prefer the stagnant waters of lakes, reservoirs, swamps or ponds, rather than those of rivers or, in general, those waters in which there are currents. The presence of that water is vital, because that is where the life of an amphibian begins. In addition, these frogs are a food source for many of the typical animals of these aquatic ecosystems, such as herons, fish, such as the dreaded "black bass" of North America, or alligators.
Although this species is native to North America, being present in almost all lakes and reservoirs, it has been spreading through various geographical areas with very varied climatology and ecological conditions. Wild bullfrog specimens can currently be found in Europe, Asia and South America, being considered an invasive species, and also quite dangerous for the ecosystems it colonizes.
Bullfrog reproduction
Bullfrogs, like other amphibians, can spend their time both in and out of the water. But during the breeding season, which would be from May to June, the bullfrog will require close proximity to freshwater,because that is where it will lay its eggs. Male bullfrogs perform courtship with female frogs, after which mating occurs. Then the female frog will lay her eggs.
A bullfrog can lay about 20,000 eggs at one time The fact that there are so many will be very important, since many tadpoles they will not survive, because they are also so active that it is not difficult for predators to detect them. In addition, these eggs have a very special feature, which is that they are unpleasant in taste for different species of lizards, which serves to prevent them from devouring them before the moment of hatching arrives. The eggs are laid on the surface of the water, where they will float for a week before hatching the tadpoles
These tadpoles will gradually mature, until those who manage to survive the multiple dangers that lie in wait for them, such as the many predators in the environment, will become frogs. With its limbs progressively developing to the size and shape of an adult bullfrog, it takes approximately 3 years to reach full size, half of that in climates especially warm.
Bullfrog feeding
These amphibians have a carnivorous diet, as well as a night-eating carnivore, that is, the time of day they feed is basically overnight. Among its multiple and varied prey we find insects such as coleoptera or lepidoptera, arachnids, worms and earthworms, snails, fish, lizards, turtles, lizards, rodents, bats, snakes and even birds. That is why it is said that a bullfrog is capable of feeding on everything that falls into its jaws, this being one of the reasons for its dangerousness in those areas where it is not an endemic species. In the case of tadpoles, feeding is mainly based on the consumption of algae, aquatic plants and certain invertebrates
Can a frog scream?
Well, it seems so, in fact the piercing scream that bullfrogs are capable of emitting when threatened or cornered can save their lives. This is so because this loud cry can surprise the predator so much that it gets distracted long enough for the bullfrog to flee, in addition, it can help the frogs that are nearby, acting as an alarm that warns them of the danger that hangs over them.
Curiosities
Do you know that the bullfrog is considered one of the most aggressive and harmful invasive species worldwide? The International Union for Conservation of Nature (IUCN) catalogs it among the 100 most aggressive invasive species, something that is not surprising, since the expansion of this amphibian around the globe is brutal, as well as the damage it causes both in the environment and in the endemic species of the region.
This happens due to the high adaptive capacities of the bullfrog, which is capable of adapting to the particularities of a wide range of ecosystems, taking advantage of all the resources they can provide, thus making local species have fewer resources at their disposal, so that many of them are doomed to dramatically disappear.
Furthermore, these frogs destroy many species as they use them as a food source, so it is not uncommon for Spain to jump the alarms when bullfrog specimens are found in the Río Ebro In Spain the bullfrog has been included in the Spanish Catalog of Invasive Alien Species and preventive measures are taken every time specimens are sighted in the middle.
But this problem has been created by us humans, as we have been the ones who have raised bullfrogs to be both our pets and part of the diet. This, combined with the strength of this amphibian and its ability to travel long distances, has allowed the bullfrog to be present in large and geographically distant territories, being spread throughout Europe, especially in Western countries.
