Canadian Toad
Encyclopedia
The Canadian Toad is a species of toad that ranges from the prairie regions of central Canada south to parts of United States upper midwest. Its name is derived from the Latin words bufonis, meaning toad, and hemiophrys, meaning eyebrow, which refers to its pronounced cranial crest between and behind the eye. As its name suggests it is a part of the family Bufonidae which means true toads. This family comprises around 500 species in more than 35 genera. Of the genera of Bufonidae, Bufo is the most widespread and well known. B. hemiophrys displays the typical toad characteristics, they lack a tail and teeth, they have horizontal pupils and their dry skin is thick and warty.
(1886) as "brown, marked on the back with a median yellowish line, and two to three rows of brown spots of medium size on each side of it." Each spot has one to two tubercles in their centers which are redder in colour than the rest of the spots. He also identified two spots on the upper lip, one below the tympanum
and a large spot that extends from below the parotid gland
to near the front of the humerus
. The parotid gland is narrow and secretes a toxin to protect it from predators. The toxins can cause irritation to the eyes and mouth and if it is ingested it can cause illness, but despite this toxin they are safe to handle.
The coronal crests of B. hemiophrys are well defined. The interorbital crests are narrow, relatively sharp-edged, non-porous and are widely separated. They run relatively parallel throughout most of their length, as far posterior as the level of the coronal crests. Posterior to that level they flare laterally to join the postorbital crests, delimiting the anterolateral edge of the postcoronal plane. Postcoronal plane is clearly defined and sloped posteroventrally. It is smooth and subtriangular, its apex directed posteriorly and it ends at the foramen magnum. Its sides are delimited anteriorly by short parietal crests. Particularly useful externally is the interorbital crest shape. In B. hemiophrys the posterior ends of the crests almost invariably diverge at least slightly where they join the postorbital crests (usually not evident externally). This provides the easiest way to distinguish Bufo hemiophrys from its close relative Bufo americanus, who share some of the same territory. In B. hemiophrys the postorbital crests are absent and the interorbital crests are fused to form a boss between the eyes, whereas, in the B. americanus the interorbital crests are well separated and join distinct postorbital crests at a right angle. The boss is a soft tissue structure characteristic of this genus. It is anchored by the previously discussed structures of the skull.
On the back external face of the tibia are several rows of dermal tubercles. The heel of the hind foot when the hind leg is extended comes level to the posterior edge of the orbit. The tubercles of the metatarsals are large. The internal one is very wide and prominent with an extensive acute edge and the external one is smaller with a free cutting edge that is transverse to the length of the tarsus.
in 1886 in Proc. Am. Philos. Soc.: 23. Cope describes the anatomical characteristics and superficial characteristics, comparing them with other related Bufo species. Cope determined that the B. hemiophrys differs from most of the other North American species because of the lack of postorbital crests and in having spots on its belly.
The closely related Bufo baxteri (the Wyoming toad) was once considered a subspecies of the B. hemiophrys. It is a relict
population that is believed to be a remnant from when the B. hemiophrys, or its ancestors, range was larger.
The range of territory covered by the B. hemiophrys is fairly large although it has been shown to be declining in southern regions of Alberta
. In Canada the B. hemiophrys’ range extends from a small southern patch in the Northwest Territories
down through eastern and central Alberta. It spreads east from there through most of Saskatchewan
and into southwestern Manitoba
. In the United States its range goes from northern Montana
and heads east into North Dakota
. Once in North Dakota it dips south into the northeastern corner of South Dakota
and also enters northwestern Minnesota
.
. The female deposits the eggs in shallow water and the male fertilizes them with his sperm as they are being deposited. Eggs are laid in the shallows of lakes, ponds, and other similar bodies of water. The water contains vascular plant debris, new grass shoots, and/or sparse cattail. This setting provides some shelter for the eggs by helping to prevent water flow from washing them away and it provides nutrients for the tadpoles
when they hatch.
(hibernation) proceeds as early as late August. The toads burrow in the earth and create little holes to sleep in. These create small mounds known as mima mounds
. Each mima mound may contain hundreds of toads. They stay there for the duration of the fall and winter, burrowing deeper as the soil temperature drops. Individual toads usually pick the same spot for torpor each year. Emergence begins once the soil thaws and the toads can dig their way out.
Description
The Canadian Toad can grow to around 7.6 cm (3 in) in length. Fully grown adult males are usually 5.6 to 6.9 cm (2.2-2.7 in), while females are a little bigger between the ranges of 5.6 and 7.9 cm (2.2-3.1 in) and they weigh between 35 and 55 g. Their colouring is described by CopeEdward Drinker Cope
Edward Drinker Cope was an American paleontologist and comparative anatomist, as well as a noted herpetologist and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy interested in science; he published his first scientific paper at the age of nineteen...
(1886) as "brown, marked on the back with a median yellowish line, and two to three rows of brown spots of medium size on each side of it." Each spot has one to two tubercles in their centers which are redder in colour than the rest of the spots. He also identified two spots on the upper lip, one below the tympanum
Tympanum (zoology)
The tympanum is an external hearing structure in animals such as frogs, toads, insects, and mammals, to name a few.-Anurans:In frogs and toads, it is located just behind the eye. It does not actually process sound waves; it simply transmits them to the amphibian's inner ear, which is protected...
and a large spot that extends from below the parotid gland
Parotid gland
The paired parotid glands are the largest of the salivary glands. They are each found wrapped around the mandibular ramus, and secrete saliva through Stensen's ducts into the oral cavity, to facilitate mastication and swallowing and to begin the digestion of starches.-Location:The parotid glands...
to near the front of the humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
. The parotid gland is narrow and secretes a toxin to protect it from predators. The toxins can cause irritation to the eyes and mouth and if it is ingested it can cause illness, but despite this toxin they are safe to handle.
The coronal crests of B. hemiophrys are well defined. The interorbital crests are narrow, relatively sharp-edged, non-porous and are widely separated. They run relatively parallel throughout most of their length, as far posterior as the level of the coronal crests. Posterior to that level they flare laterally to join the postorbital crests, delimiting the anterolateral edge of the postcoronal plane. Postcoronal plane is clearly defined and sloped posteroventrally. It is smooth and subtriangular, its apex directed posteriorly and it ends at the foramen magnum. Its sides are delimited anteriorly by short parietal crests. Particularly useful externally is the interorbital crest shape. In B. hemiophrys the posterior ends of the crests almost invariably diverge at least slightly where they join the postorbital crests (usually not evident externally). This provides the easiest way to distinguish Bufo hemiophrys from its close relative Bufo americanus, who share some of the same territory. In B. hemiophrys the postorbital crests are absent and the interorbital crests are fused to form a boss between the eyes, whereas, in the B. americanus the interorbital crests are well separated and join distinct postorbital crests at a right angle. The boss is a soft tissue structure characteristic of this genus. It is anchored by the previously discussed structures of the skull.
On the back external face of the tibia are several rows of dermal tubercles. The heel of the hind foot when the hind leg is extended comes level to the posterior edge of the orbit. The tubercles of the metatarsals are large. The internal one is very wide and prominent with an extensive acute edge and the external one is smaller with a free cutting edge that is transverse to the length of the tarsus.
Taxonomy and Systematics
The B. hemiophrys was first described by Edward Drinker CopeEdward Drinker Cope
Edward Drinker Cope was an American paleontologist and comparative anatomist, as well as a noted herpetologist and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy interested in science; he published his first scientific paper at the age of nineteen...
in 1886 in Proc. Am. Philos. Soc.: 23. Cope describes the anatomical characteristics and superficial characteristics, comparing them with other related Bufo species. Cope determined that the B. hemiophrys differs from most of the other North American species because of the lack of postorbital crests and in having spots on its belly.
The closely related Bufo baxteri (the Wyoming toad) was once considered a subspecies of the B. hemiophrys. It is a relict
Relict
A relict is a surviving remnant of a natural phenomenon.* In biology a relict is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas....
population that is believed to be a remnant from when the B. hemiophrys, or its ancestors, range was larger.
The range of territory covered by the B. hemiophrys is fairly large although it has been shown to be declining in southern regions of Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
. In Canada the B. hemiophrys’ range extends from a small southern patch in the Northwest Territories
Northwest Territories
The Northwest Territories is a federal territory of Canada.Located in northern Canada, the territory borders Canada's two other territories, Yukon to the west and Nunavut to the east, and three provinces: British Columbia to the southwest, and Alberta and Saskatchewan to the south...
down through eastern and central Alberta. It spreads east from there through most of Saskatchewan
Saskatchewan
Saskatchewan is a prairie province in Canada, which has an area of . Saskatchewan is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, and on the south by the U.S. states of Montana and North Dakota....
and into southwestern Manitoba
Manitoba
Manitoba is a Canadian prairie province with an area of . The province has over 110,000 lakes and has a largely continental climate because of its flat topography. Agriculture, mostly concentrated in the fertile southern and western parts of the province, is vital to the province's economy; other...
. In the United States its range goes from northern Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
and heads east into North Dakota
North Dakota
North Dakota is a state located in the Midwestern region of the United States of America, along the Canadian border. The state is bordered by Canada to the north, Minnesota to the east, South Dakota to the south and Montana to the west. North Dakota is the 19th-largest state by area in the U.S....
. Once in North Dakota it dips south into the northeastern corner of South Dakota
South Dakota
South Dakota is a state located in the Midwestern region of the United States. It is named after the Lakota and Dakota Sioux American Indian tribes. Once a part of Dakota Territory, South Dakota became a state on November 2, 1889. The state has an area of and an estimated population of just over...
and also enters northwestern Minnesota
Minnesota
Minnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...
.
Diet
The tadpoles of B. hemiophrys eat plant debris and other nutrients found in the waters in which they were spawned by way of suspension feeding. Juvenile B. hemiophrys’ dine mainly on small ground dwelling Coleoptera (beetles). The adult Canadian Toad's diet is mainly insects, the most important of these being the Coleoptera (beetles) and Hymenoptera (ants, bees, wasps, and sawflies). The small amount of non-insect food they consume is mainly small spiders.Reproduction
Breeding for the B. hemiophrys typically commences during early emergence in late April to early May and goes until August or September. It takes place in aquatic environments. The male grasps the female in a process called amplexusAmplexus
Amplexus is a form of pseudocopulation in which a male amphibian grasps a female with his front legs as part of the mating process...
. The female deposits the eggs in shallow water and the male fertilizes them with his sperm as they are being deposited. Eggs are laid in the shallows of lakes, ponds, and other similar bodies of water. The water contains vascular plant debris, new grass shoots, and/or sparse cattail. This setting provides some shelter for the eggs by helping to prevent water flow from washing them away and it provides nutrients for the tadpoles
Tadpoles
Tadpoles are a psychedelic rock band formed in 1990 in New York City by Todd Parker , Michael Kite Audino and Josh Bracken In 1992, Nick Kramer , David Max and Andrew Jackson of the fledgling Manhattan group, Hit, joined the Tadpoles after putting Hit on hiatus.In 1993 Kite and Jackson left the...
when they hatch.
Life cycle
B. hemiophrys lays eggs in strings of 6000 eggs and can lay up to 20,000 eggs each year. The eggs take around four to five days to hatch. The tadpoles live in the water where they hatched for seven to eleven weeks. During that time they go through metamorphosis into juvenile toads, feeding off of the plant nutrients in the water by suspension feeding. Juveniles stay near the water and are usually found in large numbers near a breeding area. Adult B. hemiophrys can be found living near lakes, streams, irrigation ditches and wetlands. The B. hemiophrys reaches maturity at around one year old in males and two years old in females and they live to be anywhere between seven and twelve years old with the oldest living in the middle of the latitudinal range sampled.Torpor
The process of torporTorpor
Torpor, sometimes called temporary hibernation is a state of decreased physiological activity in an animal, usually characterized by a reduced body temperature and rate of metabolism. Animals that go through torpor include birds and some mammals such as mice and bats...
(hibernation) proceeds as early as late August. The toads burrow in the earth and create little holes to sleep in. These create small mounds known as mima mounds
Mima Mounds
Mima mounds is a term used for low, flattened, circular to oval, domelike, natural mounds found in the northwestern United States, Idaho, Oregon, and Washington, that are composed of loose, unstratified, often gravelly sediment that is an overthickened A Horizon...
. Each mima mound may contain hundreds of toads. They stay there for the duration of the fall and winter, burrowing deeper as the soil temperature drops. Individual toads usually pick the same spot for torpor each year. Emergence begins once the soil thaws and the toads can dig their way out.