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Canadian Herpetological Society Société d'Herpétologie du Canada |
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Fowler's Toad
Anaxyrus fowleri
Family: Bufonidae
Until recently, the Fowler’s Toad was in the genus Bufo, but it is now in the genus Anaxyrus.
COSEWIC status:- Endangered
- Endangered
- Least Concern
Description
The Fowler’s Toad is a medium-sized toad that can grow up to 9 cm in body length, although most individuals are much smaller than this. Individuals are typically grey to light brown but are sometimes greenish grey, dark brown or reddish-brown, and they have small dark spots on the back that typically each contain 3–5 wart-like bumps. The belly is white or cream-coloured with little-to-no patterning, but there may be a single dark spot in the centre of the chest and adult males have a dark throat. Fowler’s Toads have granular skin with large wart-like bumps, a large, kidney-shaped parotoid gland behind each eye, and pronounced cranial crests (two raised ridges between the eyes). The legs are short and the hind feet have moderate webbing between the toes. Larvae (tadpoles) have long tails with a large fin and lack front legs (newly hatched tadpoles are legless). Young larvae are black with a clear tail fin, but they become slightly less dark and gain brown, brass or golden flecking as they age. The larvae typically grow up to 2.5 cm in total length before metamorphosis. The call is a high-pitched trill that sounds like a droning scream (e.g., “waaaaah”).
Similar Species
The Fowler’s Toad can be confused with the American Toad, but it has three or more wart-like bumps in each dark blotch on its back and a white-cream belly mostly lacking patterning, while the American Toad has only one or sometimes two bumps per blotch and dark-coloured mottling on the belly.
Distribution
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The Fowler’s Toad has a very limited distribution in Canada that is restricted to a few isolated locations along the north shore of Lake Erie (Rondeau, Long Point, and Niagara areas). This species has a very large distribution in the U.S., extending from Iowa east to southern New Hampshire and south to the Florida panhandle and eastern Texas.
Habitat
Fowler’s Toads inhabit areas with loose, well-drained sandy soils, and in Ontario they occur in sand beach and dune habitats associated with the Lake Erie shoreline. In Ontario, individuals breed in small, shallow, permanent or temporary wetlands and ponds that are typically within a few hundred metres of Lake Erie shoreline. Individuals hibernate by burrowing below the frost line in sand dunes.
Biology
In Canada, Fowler’s Toads hibernate during the winter and are typically active from late April until late September or early October. Males call to attract females during the breeding season, which occurs between late April and early June in Canada, depending on weather patterns. During breeding, the male grasps the female (amplexus) and fertilization occurs externally in aquatic habitats as the female lays eggs. The female lays 2,000–10,000 eggs in two long strings that are often entwined with vegetation. The eggs are black on top and tan to yellow underneath and are surrounded by a clear jelly envelope. The eggs develop rapidly and hatch in 2–7 days, depending on water temperature, and the tadpoles transform into juvenile toads after about 6-8 weeks. At northern latitudes, males reach sexual maturity in 1–2 years, while females do not mature until they are 2–3 years old. Fowler’s Toads can live for up to 5 years, but many individuals do not live that long. Fowler’s Toads are primarily nocturnal and forage along the Lake Erie shoreline in the evening for a wide range of insects, particularly ants and beetles. Toxins and noxious secretions that deter predators are produced by glands in the toad’s skin, particularly in the parotoid glands and the wart-like bumps. During the day, individuals burrow into the upper beach and dunes or hide under driftwood. Individuals may travel several kilometers along the beach between breeding and hibernation sites.
Threats
Urban and cottage development, shoreline hardening, and “beach grooming” (the conversion of natural beaches into manicured areas for human use) have resulted in significant and widespread loss of Fowler’s Toad habitat in Canada, and these activities continue to threaten this species’ remaining habitat. The almost complete loss of breeding habitat resulting from the rapid invasion of the highly invasive European Common Reed (Phragmites australis australis) further threatens the persistence of this species throughout most of its Canadian range, and it has virtually removed all breeding habitat at Long Point; although the Canadian Wildlife Service has subsequently created additional breeding habitat for the species, it remains to be seen if the toads will persist at that site in the long-term. Pollution, such as pesticides, agricultural effluent and road salt, can be detrimental to frog and toad populations by causing direct mortality as well as developmental deformities. Road mortality is less of an issue for this species than many other Canadian frogs, but high rates of road mortality may still occur when roads are within close proximity to the Lake Erie shoreline. Pathogens such as chytrid fungus and Ranavirus can cause mass mortality of frog and toad populations. Climate change may also pose future threats to this species.