During breeding season B. canorus males assemble in the day and call to the females in choruses. Their melodious calls are often mistaken for bird calls.
Communication Channels: visual ; tactile ; acoustic
Other Communication Modes: choruses
Perception Channels: visual ; tactile ; acoustic ; chemical
In addition to its listing as an endangered animal on the IUCN Red List, Anaxyrus canorus is a Category 2 candidate for listing as an Endangered Species by the United States fish and Wildlife Service. Vehicular traffic kills, prolonged periods of drought, and disease all claim partial responsibility in the rapid decline of Anaxyrus canorus. Attempts are being made at various zoological institutions throughout the U.S. to successfully breed and reintroduce this species back into its native range.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: endangered
Yosemite toads lay their eggs in shallow pools of water from May to mid August. Eggs hatch in 10 to 12 days and tadpoles metamorphose into adults seven to nine weeks after hatching. The first few years of Anaxyrus canorus lives are not reproductive. Females reach reproductive age at four to six years and males at three to five years.
The biggest cause of mortality among tadpoles is desiccation. When the snowfall is low the pools of water that form in the spring dry up too quickly for the toads to metamorphose in time. Recent drought in California may be one reason this toads' population has greatly declined.
Development - Life Cycle: metamorphosis
The poison in the paratoid glands of the Yosemite toads irritates the skin and causes inflammation, and may be dangerous to humans if it gets into the eyes and mouth.
Negative Impacts: injures humans (poisonous )
Yosemite toads may be beneficial to people by controlling populations of insects. The poison in the paratoid glands may also be beneficial once researched.
Positive Impacts: research and education; controls pest population
The Yosemite toads and tadpoles provide a minor food source for birds and snakes in the Sierra Nevada Mountain ecosystem. Their number and success may be an indicator of the amount of pollution in that ecosystem, but this has not yet been determined. The toads' soil burrowing habits may also contribute minimally to the aeration of the soil.
Ecosystem Impact: soil aeration
The feeding patterns of the adult and larvae Yosemite toads differ. Anaxyrus canorus larvae eat plankton and detritus, while the adults are primarily insectivorous. In the summer, hymenopterans are a major part of the toads' diet. Some specific foods of B. canorus are ants, centipedes, spiders, ladybird beetles, mosquitoes, weevils, tenebrionid beetles, and millipedes.
Animal Foods: insects; terrestrial non-insect arthropods
Plant Foods: phytoplankton
Other Foods: detritus
Primary Diet: carnivore (Insectivore )
Yosemite toads are found in a small area of the Sierra Nevada Mountains in California. They have never been found outside of California. Anaxyrus canorus range from the Blue Lakes region of Ebbets Pass to Kaiser Pass located near Evolution Lake in the Darwin Canyon area. They are found at high elevations in only two Californian counties, Alpine and Fresno counties.
Biogeographic Regions: nearctic (Native )
Yosemite toads are found in wet mountain meadows, often near pine forests. Even though they spend most of their time on land, they are never far from a permanent body of water. In their juvenile stage, Yosemite toad tadpoles swim in shallow pools of melted ice water, and in slow moving mountain streams. Anaxyrus canorus live at high elevations, anywhere from 1950 meters to 3450 meters up on a mountain side. These grassland amphibians burrow under the soil, crawl beneath rocks and fallen logs and seek shelter in abandoned rodent holes during the night.
Range elevation: 1950 to 3450 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: savanna or grassland ; mountains
Aquatic Biomes: rivers and streams; temporary pools
B. canorus is a long living species. Females live at least 15 years while males live shorter lives of at least 12 years.
Range lifespan
Status: wild: 15 (low) years.
Anaxyrus canorus are moderate size amphibians ranging from 4.5 cm to 7.5 cm. They show the highest degree of sexual dichromatism, different coloration between sexes, found among Californian toads. As in most sexually dimorphic animals, males exhibit brighter colors than females. Yosemite toad males are olive green to yellow green with small dark flecks, while females are gray or brown with large dark spots.
The young tadpoles look nothing like the adult toads, but it only takes them 7 to 9 weeks to metamorphose into adults. Yosemite toads are closely related to three other toads, the black, western and Amargosa toads. Together they make up the "boreas group." The Yosemite toads' high degree of sexual dichromatism distinguishes them from their relatives. Other features that distinguish the A. canorus from closely related species are their smaller size, wider paratoid glands and lack of a vertebral stripe.
Range length: 4.5 to 7.5 cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry ; poisonous
Sexual Dimorphism: sexes colored or patterned differently; male more colorful
It may be that the coloration of B. canorus makes it hard to spot for predators. These toads' main defense mechanisms against predation, however, are their poison glands. Like many other toads, this species has enlarged paratoid glands at the side of its neck. The paratoid glands secrete a white poison that protects the Yosemite toads from prospective predators by causing nausea, inflammation of the mouth, or irregular heart beat. This poses a danger to the toads' predators and can be irritating to humans if it gets into the mouth or eyes. In extreme cases the poison can cause death to its ingestor. The taste of the mucous-like poison is also very unpleasant.
Known Predators:
Anti-predator Adaptations: cryptic
Yosemite toads spawn, lay eggs, in shallow pools and slow moving streams in mountain meadows. After hibernation the males leave the meadows and search for water. They arrive at their breeding sites several days before the females. Both sexes are active during the day and there are about ten times as many males at breeding sites as females. Males stay at an individual site for a maximum of two weeks and females only for a few days. Both sexes try to increase their fitness by mating as often as possible with as many partners as possible. The males try to attract their mates by emitting very melodious sounds during the day. Many people mistake the mating calls of the Yosemite toads for songs of spring birds. Canorus means "tuneful" in Latin.
Mating System: polygynandrous (promiscuous)
Breeding season of A. canorus begins in May, when the ice melts and forms shallow pools, and continues until mid August. Like most frogs and toads, Yosemite toads have external fertilization. The females lay their eggs in single or double strands and sometimes in clusters in shallow water and the males fertilize them. Females may lay anywhere from 1500 to 2000 eggs. These hatch in less than a week and a half and metamorphose into adults in about two months. A temperature of below 31 degrees Celsius must be maintained in order for the eggs to develop. For the larvae to survive, a temperature of less than 36 degrees Celsius is necessary. Adults do not seem to react to varying temperatures during their active season; instead they are sensitive to moisture. The females reach reproductive age at four to six years and males at the age of three to five. Anaxyrus canorus have been known to hybridize with Anaxyrus boreas in the northern parts of their range.
Breeding season: May to mid August
Range number of offspring: 1500 to 2000.
Range time to hatching: 10 to 12 (days till eggs hatch) days.
Range age at sexual or reproductive maturity (female): 4 to 6 years.
Range age at sexual or reproductive maturity (male): 3 to 5 years.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous
Yosemite toads do not exhibit parental care. After eggs have been fertilized both parents go in search of other mates.
Parental Investment: no parental involvement
