Anaxyrus americanus, the American toad, is the most widespread toad species in North America, found throughout the eastern half of Canada and the United States. SREL Herpetology describes it as the most widely distributed North American bufonid, found throughout the eastern United States and Canada, excluding most of Florida3. It is a mid-sized, warty toad, typically 50–100 mm (2.0–3.9 in) long1, with a record length of 111 mm (4.4 in) reported for the widespread eastern subspecies, while a dwarf subspecies reaches only about 6 cm (2¼ in)2.
Identification
Colour and pattern vary, especially in females, running from brown or grey to reddish, olive or tan, often with yellow or tan patches and irregular dark spots and a light stripe down the middle of the back. The clearest field mark sits in the warts: Animal Diversity Web notes the dark spots on the back usually hold only one or two warts each, plus enlarged warts on the tibia, below the knee. The sexes differ at the throat: males carry a black or brown throat, females a white one. The belly is usually spotted, more heavily so toward the front, and the parotoid glands behind the eyes are the same colour as the surrounding skin, not a contrasting shade; the raised cranial crests on the head almost never touch the parotoid glands, another useful check in the hand. Calling males puff their throats out like a large, inflatable balloon1 to produce a high trill lasting 6–30 seconds3, likened to a ringing telephone2.
Habitat and range
Across its range the species occupies forests and flat grassland; Animal Diversity Web adds that they are also common in backyards, gardens and agricultural areas, with toads sheltering by day beneath porches, boardwalks, flat stones, boards, logs and wood piles1. Breeding, though, depends on one specific kind of water: a semi-permanent freshwater pond or pool with shallow water, sited near dense patches of vegetation that give cover and hunting ground2 once the toads move back onto land; SREL Herpetology specifies fish-free water such as temporary ponds, roadside ditches or lake margins. The range itself runs from eastern Manitoba and Quebec to the Maritime Provinces and south through the Midwest, Northeast and Southeast to east Kansas, the Dakotas, Oklahoma and Texas3.
Behaviour and breeding
Breeding begins as early as January–February in the Southeast, extending March to July across most of the range; Animal Diversity Web narrows the peak to March or April, sometimes into July. A female lays 2,000–20,000 eggs in two long strings, though Animal Diversity Web gives a narrower 4,000 to 8,000 eggs in two rows for the same species; either way the eggs come wrapped in jelly, countershaded lighter below and darker above. The eggs hatch within 3–12 days, and tadpoles complete metamorphosis in 40–70 days, a window SREL Herpetology gives more loosely as one to two months. Outside the breeding season, adults hunt after dark, taking ants, beetles, moths and earthworms; Animal Diversity Web adds slugs and snails to the list and says a toad can eat up to 1,000 insects in a day. Tadpoles instead graze algae and detritus. In the wild, most American toads probably live only a year or two, though some live past 10 years there, and one captive toad reached 36 years old. The parotoid glands and warty skin secrete bufotoxins, which Animal Diversity Web says can make many animals very sick1 if swallowed or rubbed into the eyes; the eggs carry the toxin too3.
Conservation
The species is listed as Least Concern4 in the IUCN Red List’s 2022 edition. Animal Diversity Web calls it the most widespread toad species in North America, with recorded predators including snakes, diving beetles, hawks, herons and raccoons; its bufotoxins can make many of these animals very sick1.
Similar species
The closest look-alike is Fowler’s toad, whose range overlaps the American toad’s in the east but differs in its warts and belly pattern: Fowler’s toad has three or more warts in its largest dark spots, not one or two, and it never shows a spotted belly. The two species also part company at the head, since Fowler’s toad’s cranial crests touch its parotoid glands, where the American toad’s almost never do. SREL Herpetology notes that hybridization with Fowler’s and southern toads is common3 where their ranges overlap. Farther west, Woodhouse’s toad is easily confused with the American toad, and the two hybridize where their ranges overlap2 in the far west of its range.
