Oklahoma is home to a diverse array of habitats. With that abundance of diverse habitats comes a diversity of frogs and toads that can be found from the clear streams in the eastern half of the state to the Great Plains of the Panhandle region. From a stream or riverbank to a wetland or a barrow ditch only holding a drop of water outside your front door, frogs and toads have adapted to live in a variety of environmental situations, even though they are sensitive to habitat change. This group of animals can easily be overlooked unless we happen to see them hopping right along in front of us. Treefrogs and some toad species for example, can be regularly found in our own backyards and can provide great benefits such as controlling pesky bug populations and preventing them from getting into our homes!
Bullfrogs are one of Oklahoma’s most commonly recognized frogs. Often observed on ponds and creek banks, bullfrogs are popular among hunters and anglers as well, because of their sizable and meaty hind legs.
Frogs and toads belong to the taxonomic order Anura and are sometimes referred to as “anurans,” which is ancient Greek for “without a tail.” They depend on water to reproduce and lay their eggs, and on sufficient land habitat to carry out their life cycle. All adult anurans have the ability to breathe or respire through their skin, whereas the tadpole larvae use gills to breathe under water. The diet shift between the tadpole and the adult also is a dramatic change. Most tadpoles are strictly herbivorous, feeding on algae and small plant fragments. On the other hand, all adult anurans in Oklahoma are opportunistic carnivores, feeding on just about any insect or small vertebrate that it can fit in its mouth. During the winter months, some frogs and toads seek a hibernacula where they will wait out the cold weather. Some will also send their bodies into a state of torpor, where their metabolism is slowed down to conserve energy in the body.
Anurans have a unique life cycle in which males and females gather at breeding sites and males call to attract females – very similar to how a male bird attracts a female bird by its song or call just before nesting season. Every species of anuran has a distinct call and, like birds, can be identified by their call alone. After the calling male successfully attracts a female, the male will grasp on to the female in a process called “amplexus” and the male begins to fertilize the eggs that are laid in the water. Most anurans are capable of laying thousands of eggs in order to increase their chances of survival. The egg eventually hatches into a vulnerable larva known as a tadpole, which grows a tail that serves as its main form of locomotion. The tadpole soon begins a process known as metamorphosis. During this process, which can sometimes only last a couple of weeks, the larvae forms front and hind legs and the tail begins to disappear and transform into the back of the animal. This aquatic and terrestrial life cycle is what sets anurans and other amphibians apart from many other groups of animals.
Oklahoma is home to nearly 30 species of anurans, and they all possess unique anatomical features. All have an external ear opening and eardrum called a tympanum, which is visible on both sides of the head. This feature allows for the deciphering of species-specific calls to attract mates. Because there may be several species of frogs or toads present at a particular water source, individuals must be able to detect the call from the opposite sex of the same species without confusion of other calls.
Anurans in Oklahoma can be broken up into five main groups: true toads, narrow-mouthed toads, spadefoot toads, treefrogs and chorus frogs, and true frogs. True toads are characterized by the presence of parotid glands, which secrete a toxin to deter predators. Most have cranial crests that can be used for identification. Narrow-mouthed toads are smooth-skinned burrowers, and most species specialize in eating ants. Treefrogs, chorus frogs, and cricket frogs belong to the same group and can be found in many different habitat types throughout Oklahoma. Treefrogs specialize in climbing trees, which they will use as their calling territories. Cricket frogs are one of the smallest in size but are also one of the most common frog species. They are mostly encountered jumping along the banks of ponds and lakes. Chorus frogs are very secretive and can be difficult to find but are the first group of frogs to start calling for mates in the early spring. True frogs can be distinguished by webbing between the hind toes, muscular legs for long jumping, and gland-like ridges running down both sides of the back.
Frogs and toads are clearly a diverse and distinctive group of animals that inhabit many different habitats. Some anuran species are of conservation need, and protection of habitat types that these species rely on will ensure their successful future in our great state.