Introduction
Toads are a kind of frog, but they’re placed in a separate sub-group because they have some distinctive characteristics that set them apart from other frogs. Here are some of the key differences:
Skin: Toads have dry, lumpy skin. They spend more time on land than frogs, and their thicker skin protects them from dehydration. Frogs are often in water and have a smooth, sometimes slippery skin.
Colour: Frogs use their vibrant colouring to attract a mate and to warn predators of their toxicity, while toads, who are usually brown, green, or grey, prefer to blend in with their surroundings.
Mobility: Toads have short hind legs and are better at walking than hopping. Frogs have long, webbed hind legs for leaping and swimming.
Eating: Frogs use their long, sticky tongues to reach out and capture insects and other food. Toads don’t have a sticky tongue so they have to walk or hop up to an insect before swallowing it whole.
Protection: Toads have parotoid glands behind their eyes that can excrete poison if the toad is being attacked by a predator or feeling stressed. Frogs don’t.
Eggs: Toads lay long strands of eggs that hang down in the water, while frogs lay their eggs in clusters that float on the water’s surface.
Tadpoles: Frog tadpoles have streamlined bodies and long tails and excel at swimming. Toad tadpoles stick to shallower water and have thicker bodies and shorter tails.
Appearance
Great Plains Toads, found in the dry grasslands of southern Alberta, Saskatchewan, and Manitoba, are medium-to-large amphibians. Their light-coloured back is covered in large, dark blotches. They have a white belly, and males have a dark throat.
Canadian Toads have a bump on top of their head. They are grey-green or brown with brownish-red warts and grey spots on a light-coloured belly. They’re found in Alberta, Manitoba, and Saskatchewan.
American Toads have two low ridges that join to form a V between their eyes and are slightly larger with smaller spots and blotches and less warts than Canadian Toads. They’re common in eastern Canada but overlap with Canadian Toads in southeastern Manitoba.
Western (Boreal) Toads, found in British Columbia and Alberta, are green or brown with a light-coloured stripe down their back and a light-coloured belly. The warty bumps on their skin are reddish-brown and sometimes surrounded by black rings.
Plains Spadefoot Toads can be found in Manitoba, Saskatchewan, and Alberta. They have a small round body and a bony lump between the eyes. Their skin is relatively smooth and moist. They are tan to dark brown with small orange/yellow spots and a white belly. They often have 4 white stripes down their back.
Great Basin Spadefoots, found in the southern interior of British Columbia, are small and tan, grey, or olive in colour with dark reddish-brown spots. Some of them have two light lines running down their back in the shape of an hourglass. Western Toads, that may be found in the same area, have bumpier skin, horizontal pupils, and large parotoid glands behind the eyes.
Calling & Breeding
Plains Spadefoot Toads can be found on short-grass prairie with sandy or gravelly soil. They spend most of their time underground. They’re explosive breeders, all of them coming out at the same time to lay their eggs in shallow temporary pools formed after a heavy rain in early spring or summer. The males call to the females with a snorelike bleat or growl that repeats every 1-2 seconds.
During breeding season, female toads use sound rather than sight or smell to home in on the males. During the call, a stream of air passes over the males’ vocal cords as they exhale. The vocal sac inflates while the nose and mouth are closed. The sac spreads the sound over a larger area than would be possible otherwise. The constant calling demands a great deal of energy as the heart and lungs are working full out, and the males lose a large amount of their body fat.
Western Toads generally lack vocal sacs, resulting in a bird-like chirping or quiet peeping.
Canadian Toads are easiest to spot in the spring when they congregate at breeding ponds. The males call to the females with a high-pitched trill that repeats every 15-20 seconds.
Male American Toads produce a long musical trill to attract females and have a different call when they release the female during often frequent mismountings.
The Great Plains Toad’s call resembles a pneumatic drill and breeding is often explosive after a heavy rainfall. Satellite males are common; they don’t call but try to intercept females attracted to a calling male.
Great Basin Spadefoot males make a hoarse, raspy bleat or snore repeated over and over and can be heard over long distances.
Habitat
Toads are amphibians and spend part of their life in water as eggs and then tadpoles before developing lungs as adults and moving on to land. They’re cold-blooded and unable to regulate their body temperature. This has its advantages as they have a low metabolism and don’t need to eat constantly, but it also means they can’t withstand extreme temperatures. They survive cold winters by burrowing below ground and come out at night when it’s cooler to eat and breed.
Western Toads can be found in a variety of habitats (wetlands, shores of lakes and rivers, forests), even mountain meadows above the snow line. They migrate considerable distances – over 6 km – between their breeding ponds, upland summer ranges, and winter hibernation spots. All the members of a local population tend to lay their eggs in the same spot every year.
Plains Spadefoot and Great Basin Spadefoot Toads, found on open grasslands, have sharp knobs (spades) on their hind feet that they use to tunnel backwards in sandy soil. Their burrows may extend as much as a metre underground.
American Toads live in forested uplands and along the margins of lakes and wetlands.
Defense Tactics
Toads employ a variety of different techniques to avoid being detected. Both adults and tadpoles freeze and use natural camouflage to blend into their surroundings. Canadian Toads stay close to water and can escape from danger by swimming into deep water. Another option is to escape by burrowing. Toads can also inflate, which makes them harder to swallow and exposes their toxic parotoid glands.
Tadpoles often have a distinctive border around their tail so that the tail and not the head is targeted. American Toad tadpoles have poison glands in their skin.
Further Information
Hot Frogs and Sizzling Salamanders: Climate Change is Pushing Amphibians to Their Limits [The Conversation]
Frogs & Toads [Canadian Herpetological Society]
Frogs and Toads [Province of BC]
Identification Key to Juvenile and Adult Amphibians of Alberta [Alberta Conservation Association]
Saskatchewan’s Frogs and Toads [EcoFriendly Sask]
Frogs and Toads of Manitoba [Frogwatch]
Nature Companion, A Comprehensive Nature App for Canada’s Four Western Provinces [EcoFriendly West]
Photo credit: https://www.flickr.com/photos/apmckinlay/24835161041
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