Amphibians
Eastern Spadefoot
Scaphiopus holbrookii · also called eastern spadefoot toad, hermit spadefoot
For most of the year the eastern spadefoot is not visible at all. It is a foot or more underground, sealed in a damp chamber, waiting. Then a warm summer storm soaks the ground, and in a single night the whole hidden population climbs out and heads for the puddles.
Overview
Scaphiopus holbrookii lives across the eastern United States wherever the soil is loose and diggable, in pine and oak woods, floodplains, fields, and dunes. It eats ground invertebrates in short bursts at the surface. Despite the name it is not a true toad — it has cat-like vertical pupils, smoother skin, and small teeth.
The spade
Each hind foot has a hard, sharp, wedge-shaped black spade on the sole, which the toad uses to dig itself straight down, backwards, with a corkscrew shuffle. It can stay buried for weeks or months.
Breeding by cloudburst
Heavy rain brings the adults out the same night to gather at temporary flooded pools and breed over just one to three nights. Because the pools dry fast, the eggs hatch in a day or two and the tadpoles can transform in as little as two weeks.
Status
Least Concern but patchy and easily missed, tied to loose soils and short-lived fish-free pools, and lost locally where those wetlands are drained.
Eastern Spadefoot: common questions
Is the eastern spadefoot a toad or a frog?
Neither exactly. It belongs to the spadefoot family, an old lineage that sits apart from both the true toads and the typical frogs. It has warty skin and a squat build like a toad, which is why it is usually called the eastern spadefoot toad, but it also has vertical, cat-like pupils, moister and smoother skin than a true toad, small teeth in the upper jaw, and no large poison glands behind the eyes. True toads have horizontal pupils, dry skin, no teeth, and prominent parotoid glands. So the eastern spadefoot is a spadefoot, a group all its own, that happens to look toad-like.
Why does it only come out when it rains?
It is adapted to survive in dry, sandy habitats by avoiding the surface almost entirely. Above ground it would lose water quickly and be exposed to predators and heat, so it stays sealed in a moist chamber below the dry topsoil, its metabolism turned down, sometimes for months. Warm heavy rain does two things at once. It soaks the soil so the toad can dig out without drying, and it fills the shallow, temporary pools the spadefoot needs to breed, pools that hold no fish because they do not last. So the toad's entire year is compressed into the handful of rainy nights when both conditions are met.
What is the smell people describe when they handle one?
A skin secretion. Like many amphibians the eastern spadefoot produces defensive compounds in its skin, and in this species the secretion has a strong, distinctive odour that people compare to roasted peanuts, popcorn, or burnt sulphur. It is not dangerous to touch briefly, but it can sting if it gets into the eyes, the nose, or a cut, and some people react to it with sneezing, watery eyes, or a mild skin rash. Washing your hands after handling one, and not touching your face, takes care of it.
How can the tadpoles grow up so fast?
They have no choice, because the pools they hatch in can vanish in two or three weeks. Eastern spadefoot eggs hatch within a day or two, and the tadpoles then feed almost constantly on algae, detritus, and, in crowded or protein-rich pools, on tiny animals and even each other, growing at a rate that lets some individuals complete metamorphosis in about two weeks. It is a gamble, since fast development means small size at transformation and lower survival, but a slow tadpole in a drying pool has no chance at all. In a pool that lasts longer, the tadpoles take more time and emerge larger.