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Upper Midwest Environmental Sciences Center

Farm ponds as critical habitats for native amphibians
A Field Guide to Amphibian Larvae and Eggs of Minnesota, Wisconsin, and Iowa
Field guide contents

American, Canadian, Great Plains, Woodhouse's, and Fowler's Toads

American Toad Bufo americanus
Canadian Toad Bufo hemiophrys
Great Plains Toad Bufo cognatus
Woodhouse's Toad Bufo woodhousii
Fowler's Toad Bufo fowleri

Status: B. americanus –Common to locally abundant in Wisconsin, Minnesota, and Iowa.
B. hemiophrys –Locally abundant in Minnesota
B. cognatus –Locally abundant in Minnesota and Iowa
B. woodhousii –Locally abundant in Iowa
B. fowleri –Locally abundant in Iowa
American Toad tadpole
(American toad tadpole)1.8 - 2.4 cm total length
field map
B. americanus
field map
B. hemiophrys
field map
B. cognatus
field map
B.woodhousii (western Iowa)
(eastern Iowa)

Toad eggs and tadpoles can be found in almost any aquatic situation, from muddy farm ponds to clear swampy areas, and are distinctively different from those of other frogs. Toads lay their eggs in long strings that may be benthic or entwined in (but not attached to) vegetation. You should be able to distinguish the eggs of any species of toad based on site location and characteristics of the envelope surrounding the eggs. Canadian Toads are found in northwestern Minnesota and have a single tubular envelope enclosing the eggs. The American Toad has a double envelope surrounding the eggs, with eggs separated by partitions. Woodhouse's and Fowler's Toads, are found in western and southeastern Iowa and have a single tubular membrane not separated by partitions. Great Plains Toads are found in western Iowa and Minnesota and have a scalloped egg string.

The larvae of different toad species are very similar. Toad tadpoles are small and black or dark brown, often with some bright metallic spots. They have a clear fin that is rounded at the tip. The eyes are dorsal and the vent is medial. Metamorphosing toads quickly acquire their unique warty skin and squatty shape.

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URL: http://www.umesc.usgs.gov/terrestrial/amphibians/field_guide/toads.html
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Page Last Modified: December 29, 2010