HerpIndiana

Eastern Spadefoot (Scaphiopus holbrookii)

Adult from Bartholomew County

Description

Morphology: A small stocky brownish or grayish Anuran with very small warts. Dorsally there are usually yellow stripes extending posterior from the eye. The underbelly is white to gray in coloration. The pupils are vertical ellipses. There are hard black tubercles on the hind feet from which it derives its name

Size: This species grows to around 2in SV length (Conant and Collins 1998, 503).

Larvae: A small dark tadpole speckled with orange. The tailfin is clear (Minton 2001, 106).

Eggs: Females lay eggs in long bands of up to a foot in length (Minton 2001, 108).

Similar Species: The body form and coloration of this Anuran make it quite distinct from the other frogs and toads of Indiana.

Distribution

The Eastern Spadefoot occurs throughout the southeastern United States and north to New England along the east coast. Their distribution in the midwestern states is spotty with isolated populations occuring in suitable habitat (Conant and Collins 1998, 504).

Due to its explosive and irregular breeding the Spadefoot's range is probably still not well known in the state. As new records surface, it appears as though Spadefoot populations follow the secondary floodplains of the White River where sandy soils are found. Other populations occur along the Ohio River in low areas and in the karst plains where they may breed in sinkholes and relict barrens.

Activity

Spadefoots are burrowers that are rarely seen above ground except to breed. There is evidence of some nocturnal foraging on rainy summer nights (Minton 2001, 106).

Breeding Season: Spadefoots are explosive breeders that may breed anytime from March through July after very heavy rains. After amplexus takes place and the eggs are deposited, the eggs hatch within a matter of days. The tadpoles transform and disperse within weeks of hatching. They do not breed during some years if ideal conditions never materialize (Minton 2001, 106-107).

Taxonomy

The Eastern Spadefoot (Scaphiopus holbrookii) has no subspecies. The Eastern Spadefoot belongs to the genus Scaphiopus and is in the family Scaphiopidae which is represented in Indiana by 1 species.

Natural History

Habitat: This species occurs in low sandy areas often in the secondary floodplains of large rivers. They have also been found in low, open areas with loose soil in the absence of sand. During the short period of time when breeding occurs, Spadefoots may be found in large numbers crossing roads or actively moving around on rainy nights. Spadefoots are rarely seen above ground at other times. They are burrowers that dig shallowly into sandy soil to conceal themselves (Minton 2001, 106)

Feeding: Spadefoots appear to feed mainly on insects, spiders, and other small invertebrates (Minton 2001, 108).

Breeding: Breeding is explosive and takes place after periods of very heavy rain, usually in low areas that temporarily flood such as farm fields and marshy prairies. Over the course of one or two nights, large numbers of these frogs emerge from the ground to gather at temporary pools where breeding takes place. Males and females join in amplexus and the females lay eggs in bands up to a foot in length while the male fertilizes them (Minton 2001, 108). After hatching, the tadpoles must develop and transform in a short period of time as most pools utilized will dry up rapidly.

Call: Spadefoots have a loud nasal call that resembles the "whank" call of a young crow (Minton 2001, 107).

Conservation: Little is known about the stability of this species in Indiana as its range within the state is not even well known. The breeding habits of this Anuran make assessing its populations difficult, but they are known to breed in flooded farmfields and in suburban areas where low, grassy lawns may flood (Minton 2001, 107) so developement likely does little to deter this species. No research has been done concerning this species in the state, but casual surveying is done to monitor known populations. Due to its seemingly limited range and isolated populations, it is considered a Species of Special Concern in Indiana.