Fowler’s Toad Anaxyrus fowleri

 

Status

No status assigned in Iowa.

Description

This is Iowa’s smallest  toad species reaching 2-3 inches (5.1-7.5 cm) in body length. Max 3 ¾ inches (9.5 cm). The ground color may be varying shades of brown or gray ranging to almost white. There are several dark spots on the back, each contains one to several small warts. A white or light middorsal stripe is usually present on the back. The belly is white and unmarked except for perhaps a small breast spot. Tadpoles have a mottled appearance. The eyes do not reach the edges of the head when viewed from above. The top half of the tail is dark, the lower half is light. Newly metamorphosed toadlets are dark in dorsal coloration, but will lighten quickly with age.

Subspecies

There are no subspecies of Anaxyrus fowleri recognized. The Fowler’s toad was formerly recognized as a subspecies of the Woodhouse’s toad, until Masta et al. (2002) elevated it to full species status. I have observed hybrids between eastern American toads and Fowler’s toads in southeastern Iowa, and they are reported from other areas as well (Blair 1941; Green 1989; Laurin and Green 1990; Sanders 1987; Johnson 1992; Volpe 1952). These specimens looked like Fowler’s toads in overall appearance with spotted bellies. Sanders (1989) states that some hybrids may be indicated by semi-bossed individuals. Hybrid offspring are apparently fertile (Blair 1941).

Similar Species

Only the eastern American toad is found within the range of the Fowler’s toad in Iowa. Eastern American toads have a belly mottled with dark pigment and a dramatically different call.

Range

The Fowler’s toad is found in sandy areas of extreme southeastern Iowa.

Habitat and Habits

The Fowler’s toad is active from April through October. Usually found in rather open sandy and woodland edge areas of southeastern Iowa. Fowler’s toads may be active during the day in mild weather, but are typically nocturnal in hot weather, although I have noted surface activity in a few specimens at air temps over 90 F (32.2 C). More typical, however, are my observations of specimens active at night on roads, especially during rainy or humid weather. They burrow in the sand or move into woodlands for thermoregulation during the day. They overwinter under the ground in the burrows of other animals or in self excavated tunnels. An adaptable species, it will thrive in the protected forested-sand prairie ecotones and the associated ponds and floodplains in southeastern Iowa. This unique habitat is extremely important, not just for the Fowler’s toad but a great many rare and uncommon amphibian and reptile species. When captured, a Fowler’s toad may puff itself up with air, urinate on its attacker, and may give a release call that causes vibration in the throat and torso. This produces a chirping sound in males, but no sound is produced in the females. Toxins produced by this toad may be distasteful to predators.

Reproduction

Fowler’s toads breed May through June. The call is a flat, buzzing sheep-like bleat, very similar to the Woodhouse’s toad’s call.  The call lasts 3 to 5 seconds long. Hybrids with eastern American toads have a “husky trill” call (Blair 1941). Typical breeding sites include oxbow ponds and marshes or flooded ditches, and most sites are usually near the Mississippi or other rivers. Strings of eggs are laid in pools that will hold water until the middle of July, when the toadlets emerge.

Food

Fowler’s toads eat insects or earthworms and even feed on harmful invertebrates in agricultural areas. In agricultural areas the possible inadvertent ingestion or absorption of pesticides and other chemicals due to the consumption of invertebrates may negatively affect this species.  

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