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The Eastern Tiger Salamander is widely distributed across the broad interior of North America, from Canada south into Mexico, but exclusive of the margins along the east and west coasts. They are found throughout most of Wyoming at elevations below 10,000 feet. They are primarily nocturnal and prefer intermittent streams, ephemeral pools, and small ponds and lakes that are free of predacious fish. Larvae have three pair of filamentous gills and demand an aquatic environment. Adults, now utilizing lungs since loosing their gills in transformation, are semi-terrestrial and need moist environments—hiding beneath rocks, logs, and debris or residing in rodent burrows—to avoid desiccation.
The body of the Tiger Salamander is dressed with a black or dark, olive-green background and cloaked with a banding, mottling, or marbling of a lighter green or yellow. Its skin, without scales or unsightly glands, is moist and smooth. The legs—fitted with un-webbed feet, four-toed up front and five-toed to the rear—are similar in size and awkwardly protrude from the body, the sides of which are draped with the folds of 13 costal grooves. The tail is muscular and laterally compressed or flattened. Its head, without external ear openings, is broad with small, non-protruding eyes whose black pupils are highlighted with flakes of gold pigmentation. There is a flap or pleat of skin (the gular fold) which accentuates the ventral junction of the neck with the upper region of the chest.
The reproductive cycle is triggered by warming temperatures and spring rains, prompting adults to aggregate in small, shallow ponds. The voiceless salamanders often make use of historical breeding sites to bring breeding individuals into proximity. During courtship, males use their heads to nudge, prod, and poke females in an effort to gain their affections. Thus enticed, a female will indicate her receptiveness by following along behind the male. The male releases a small packet of sperm (a spermatophore) from his cloacal opening, leaving it on the substrate as he ambles away in search of another partner.
The female positions herself over the package and picks it up with the lips of her cloaca. The eggs are fertilized internally and pass from her body as she attaches them to submerged vegetation. In her season, she may release as many as 1000 eggs; these are deposited singly or in short rows or clusters of up to 100. The bi-colored eggs, brown above and cream below, are encased in a gelatinous capsule. The eggs hatch several weeks later and the larvae begin feeding voraciously. The larvae may transform into the adult body form the same year, or they may overwinter in the larval stage and transform the following year. They may also fail to transform at all and reach a form of sexual maturity in a neotenic stage, a process known as paedomorphosis (a type of change where juvenile characteristics are retained in the adult form).