History and origin
The American bullfrog was first described by Shaw in 1802, the scientific name of this species is Lithobates catesbeianus, formally Rana castesbeiana, Rana from Latin meaning frog, and catesbeianus because this species was dedicated to Catesby, an English naturalist who discovered this frog in Caroline, USA. Lithobates is from Greek and is composed of two words, 'litho' meaning 'stone', and bates 'to walk'.

Characteristics
This species is characterised by many factors, at a first glance, they are much larger then our native frogs of Europe. Their tadpoles are also very large and very different from other tadpoles. They lack dorsolateral folds.

Description
=Size=
- Eggs: The eggs are about 1.5 to 2 mm in diameter, laid separate balls that each measure about 6 to 8 mm in diameter.
- Tadpoles: The tadpoles measure up to 140 mm, sometimes even more.
- Juveniles: The juveniles measure about 40 mm long when they exit the water.
- Adults: Adults measure up to 200 mm long.
=Morphology=
- Eggs: The eggs are laid in individual balls grouped in a single cluster of between 10000 to 25000 eggs.
- Tadpoles: They have a short but large tail, not coming up onto the back. On top of the back they have what looks like wrinkles. they have large eyes that are on the sides of the head.
- Adults: A huge, heavily built frog with no dorsolateral folds. They have a larger then long head and rounded snout. They have quite smooth skin. They have no paratoid glands, they have very complete hind feet webbing. Their pupils are horizontal and they have an internal vocal sac.
=Patterns & colours=
- Eggs: They are brownish on top and creamy or white on the underside.
- Tadpole: They can be greenish with darker spots, their belly is yellowish and their tail is usually scattered with yellow markings.
- Adult: They are usually quite dark with darker blotches along the back, flanks and limbs. The back colour varies from light brown to dark brown. They may be yellowish. The head is usually quite greenish. Their eyes are golden. Their bellies are whitish with a series of darker speckles.

Geographical range
Native to north America, in Europe they have been introduced to northern Italy as well as smaller isolated populations along the western Italian coast. In France they are found in 'Aquitaine' (south western France). Other populations can be found in western Spain and the Netherlands.

Subspecies
None described.

Sexual differences
Males have nuptial pads on their hands. The males eardrum is larger then the females. The males throat may be yellowish due to their vocal sac.

Seasonal variations
Males nuptial pads cary in colour being darker during the breeding season.

Diet
They feed mainly on other frogs, but also on snakes, baby birds (including ducks).

Defensive habits
They will emit a defensive call if caught, otherwise they will jump into the water and hide.

Reproduction
In France, the exact routine for this species is unknown, however they seem to breed like other Rana species (sub-order Pelophylax, water frogs). The breeding season can last up to 1 to 2 months (March to April). Males are seen sitting on an algae rock singing at each other as if they are running a singing competition. When a female comes within eye distance of our singing males, the singing stops and the most impatient males immediately swim over to her, they then take the female to an area in the water with many plants, sticks and in general a lot of vegetation. Then there is another competition between the males, but this time there's a judge, the female. They sing at each other an the one who has the most piercing sound should normally win the females wishes to breed. The winning male will climb onto the females back and hold her behind her front legs, the male wraps his arms around her and sometimes the males thumbs will come into contact. The female will then eject a small clutch of eggs which the male fertilizes on their way out of the female. After a short pause, the same happens again. If they are disturbed they will dive and separate, often swimming in the opposite direction, if the female comes to the surface and can't see the male she was just with, she will take another male and this procedure will reproduce until the female is empty.

Sexual maturity, life span
The average life span for Lithobates catesbeianus is about 10 years, they reach their sexual maturity in their third year for females and in their second year for males.

Habits
They are active by day and night. They are very aquatic.

Call
A slow, cow like deep call, sounding like a donkeys 'hi-han' but without the 'hi', they usually call from the shallow water, sound (p)www.oreilleverte.com:

Habitat
Found under 50 meters in altitude. They live in anything wet, they are very aquatic.

Predators
Herons present the biggest threat, the eggs and tadpoles are sometimes eaten by birds, fish and snakes.