American toad
Bufo americanus

The American toad can be identified by inspection of the dark blotches randomly distributed about the back (Fig. 3). Usually only one or two warts are enclosed in each blotch. In addition, the L-shaped cranial crests do not usually contact the parotid glands directly, or if they are connected to the parotid glands, it is by a spur connection rather than by direct contact. The breast is usually creamy in color with dark mottling. The warts on the tibiae are enlarged in comparison with those on the femoral area or tarsus. Toads reach lengths of about 75 mm, and females average larger than males. Ground color of the skin varies from yellowish through hues of brown to black and varies with changes in stress, temperature and humidity.

Fig. 3. American toad

• Dark blotches on the back of the American toad usually enclose only one or two warts.
 
• Cranial crests do not contact the parotid glands directly, but they may contact the parotid gland through a spur connection.
 
• Warts on the tibiae are enlarged in comparison with those on the femoral area or tarsus.

American toads emerge from hibernation in March and soon their long, melodious trills resound through valleys and across fields and woodlots from early to mid-April through June. To most Ohioans familiar with frog and toad calls, the continuous, pulsed call of the American toad of 4-20 seconds duration is the most musical of our amphibian sounds (Fig. 4). The round, mottled gray vocal sac of the male is greatly inflated and vibrates rapidly during the call.

	Fig. 4. Call of the American toad

 Call of the American toad (46 seconds, 364 KB)
 Excerpt (14 seconds, 115 KB)
 A chorus of American toads (63 seconds, 496 KB)

• The continuous, pulsed call or trill of the American toad may exceed 4-20 seconds in duration.
• The call in the spectrogram has a dominant frequency of 1700 Hz and a duration of 5.1 seconds.

During the breeding season the males have dark horny pads on their first two fingers that assist them in clasping females during breeding, a process called amplexus. Males call from shallow, temporary ponds, lakes, rivers, and water-filled tire ruts to attract females ready to breed and to advertise their positions to other males.

During amplexus, eggs from the female and sperm from the male are shed simultaneously into the water where fertilization occurs. Toad eggs are laid in tubes forming long strings, one from each of two ovaries (Fig. 5). A string of eggs when outstretched may reach 6-20 m in length, and a clutch may contain 15,000 eggs. Individual eggs are 1.5 mm in diameter, but the tube absorbs water and expands to a diameter of 4 mm or greater. Hatching occurs in 3-12 days, depending upon the water temperature, releasing free-swimming larvae or tadpoles. Development within the egg occurs more rapidly at higher temperatures. Tadpoles form schools and feed voraciously for 40-70 days, reaching lengths of about 12 mm before undergoing transformation. During transformation great changes in body form and structure take place. The aquatic tadpole grows legs, absorbs its tail, and changes its diet from plants and detritus to insects and other animals. Toadlets of 10-12 mm total length may be found on land beginning in late May through mid-summer. Sexual maturity is reached in 2-3 years.

Fig. 5. Eggs of the American toad

Toads may be found in forests, fields, yards, vacant urban lots, just about anywhere that objects are present for them to hide under and where breeding ponds occur nearby.

• Toad eggs are laid in tubes forming long strings. A clutch may contain 15,000 eggs and may extend 20 m in length. Individual eggs are 1.5 mm in diameter when laid but swell to 4 mm upon hydration.
• Dark eggs at the right of the photograph are fresh laid; whereas those on the left are hours old, and the egg tube has swollen and become clouded with silt.