Eastern Spadefoot

Media
Image of an eastern spadefoot
Status
Name
Species of Conservation Concern
Scientific Name
Scaphiopus holbrookii
Family
Scaphiopodidae (North American spadefoots) in the order Anura (frogs)
Description

The eastern spadefoot is a stout, toadlike amphibian with large, protruding eyes, vertically elliptical pupils, short legs, and large feet. Small, inconspicuous parotoid glands (resembling a wart behind the eye) are present. There is no raised area (boss) between the eyes. Overall color is light brown to yellow brown. The head, back, and upper parts of the legs are mottled with dark brown. The amount of dark brown on the back may be great enough to form 2 or 3 light yellow-brown, lengthwise stripes in a pattern resembling a lyre. The belly is pale white to gray. The inner surface of each hind foot has a sickle-shaped spur or “spade.”

The male's call is a coarse wank, berrr, or errrah that is repeated every few seconds. Some say it sounds like a young crow. A chorus sounds like a quacking orchestra of countless wanks.

Spadefoots are known to produce skin secretions that can be noxious to other animals. When handling a spadefoot, it is best to avoid touching your face or eyes until you have washed your hands.

Similar species: The plains spadefoot, which occurs in counties along the Missouri River, is distinguished by the presence of a boss (a raised area) between the eyes and by having a wedge-shaped spade at the base of each hind foot.

The North American spadefoot family is represented by two genera, Scaphiopus and Spea, and only two of them occur in Missouri. Spadefoots, often called spadefoot toads, are not true toads (family Bufonidae), although they resemble toads in general appearance and habits. The name "spadefoot" comes from a special tubercle on the hind feet that is shaped like a spade and is used for digging into sand and soil; spadefoots are highly adapted for living underground, and they are explosive breeders in ephemeral (temporary, seasonal) pools. They have smoother skin than true toads (genus Anaxyrus), and the pupils of their eyes are vertical.

Note that another species, Hurter’s spadefoot (Scaphiopus hurterii), has not been found in Missouri, but it could possibly one day be found within our borders. Its range is to the southwest of our state, and it extends into north-central and northwestern Arkansas. It is a secretive species but an explosive breeder. In Missouri, it would most likely be found on nights with heavy rainfall along the southern and southwestern border with Arkansas and Oklahoma, especially in sandy areas within river floodplains. Its range would likely not overlap with our other spadefoot species. To date, however, the Hurter’s spadefoot has not been found in Missouri.

Size

Adult length (snout to vent): 1¾–2¼ inches; occasionally to 3 inches.

Where To Find
Eastern Spadefoot Distribution Map

Eastern counties along the Mississippi River and in southeastern Missouri.

Eastern spadefoots spend most of their time in burrows dug with their hind feet. They are nocturnal and become active on warm, damp, or rainy nights. They occasionally occur in wooded areas, but they seem to prefer open fields where loose sand and soil facilitate burrowing. Spadefoots are most common within the sand prairies and sand savannas of southeastern Missouri. They are mostly observed during the breeding season and seldom seen at other times.

The diet includes a variety of invertebrates, especially ants, beetles, flies, grasshoppers, crickets, termites, and worms.

A Missouri species of conservation concern because of its restricted range, the destruction or modification of natural sand prairies, and limited knowledge on its basic biology.

Taxonomy: Often called spadefoot toads, spadefoots are not true toads, nor are they true frogs, either. They’re named for a feature on the inner surface of their hind feet, a spadelike spur that helps them to dig their burrows.

Life Cycle

Breeding takes place after heavy rains, usually between March and June in southeastern Missouri. In some years, however, warm torrential rains in February cause early breeding, and this species is likely to breed in the summer after heavy rains. Heavy rains (over 1 inch) are needed to stimulate breeding aggregations. If heavy rains do not occur, spadefoots will not breed during that season.

Most breeding takes place after sunset after heavy rains, but daytime chorusing may occasionally be heard during favorable weather. Eastern spadefoots breed in temporarily flooded fields, ditches, or other fishless, temporary pools. In Missouri, a breeding chorus generally ranges from 20 to 40 individuals calling at a site. However, it is not uncommon to hear a very large chorus during favorable weather conditions. Exceptionally heavy rains can stimulate widespread breeding of thousands of individual spadefoots. Interestingly, these explosive breeders may be nearly silent the night following the largest choruses.

The tangled eggs are laid in loose, wide strands or bands 1–3 inches wide and 1–12 inches long and are attached to submerged vegetation or twigs. A female can produce 1,000–2,500 eggs or more. Eggs hatch in 1–15 days, and tadpoles can metamorphose in 2–5 or more weeks, depending on water temperature.

Along the Mississippi River and in the Bootheel, extensive agriculture practices in former sand prairie habitat, as well as urban development, have destroyed and modified many of the natural ephemeral pools where spadefoots breed. Increased survey efforts over the past 15 years has documented that spadefoots are more common than once believed in southeastern Missouri. Management of this species should focus on maintaining fishless, temporary wetlands for breeding and tadpole growth within former sand prairie habitat.

Just when you think you have sorted all the animals you know into easy categories, you encounter a toadlike creature that is neither toad nor frog. The vertical pupils are a clue that something’s strange here — true toads’ pupils are horizontal! There is always something new to discover in nature.

A predator of insects, the eastern spadefoot and a host of other small insectivores function to control the populations of the hosts of those creatures. Meanwhile, the frogs, and their own thousands of eggs and many tadpoles, are eaten by larger predators.

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About Reptiles and Amphibians in Missouri
Missouri’s herptiles comprise 43 amphibians and 75 reptiles. Amphibians, including salamanders, toads, and frogs, are vertebrate animals that spend at least part of their life cycle in water. They usually have moist skin, lack scales or claws, and are ectothermal (cold-blooded), so they do not produce their own body heat the way birds and mammals do. Reptiles, including turtles, lizards, and snakes, are also vertebrates, and most are ectothermal, but unlike amphibians, reptiles have dry skin with scales, the ones with legs have claws, and they do not have to live part of their lives in water.