Belonging to the Ranidae family, this frog shares its habitat with two other similar-looking species in its home range (the Red-legged and Cascades Frogs).
This frog can be recognised by its color which varies from almost a dark brown to a reddish color on top and a cream color underneath with mottled pattern from the throat down. Adults often have red, orange or yellow on the undersides of their legs. Its eyes seem to be looking upward or at least placed higher on its head than other frogs. Its feet are fully webbed and most individuals have a white mustache line that goes all the way back to the shoulder. Its spots seem to have indistinct edges, much like a spot of paint sprayed from a spray paint cannister and sometimes there is a light dot in the center of the spot.. Spotted Frogs has shorter legs than similar species. Younger frogs have two dorsal-lateral folds along the sides of their back. This may be less obvious or absent in adult frogs. The Spotted Frog prefers to stay near water year round when it is not hibernating. It can be found in clean water ponds, backwaters of streams and rivers and reedy shores of lakes where it is active in the daytime.
Male frogs call early in the spring in February and March. In fact, they are probably the earliest frog to spawn in B.C. Their call is a low grunting sound made while in the water. They are very choosey about the quality of water where they lay their eggs and avoid disturbed areas such as watering holes for grazing animals or habitat that has been developed. They have been known, however, to use human-made ponds that have been established for 2 years or more. . They prefer shallow water about 15 cm (six inches) deep, with warm water and reedy edges.
Fertilization of eggs is external and a clear jelly egg mass the size of a tennis ball or so is laid attached to submerged sticks and plants within 2 meters of shore. The number of frogs in an area can be determined by the number of egg masses laid together as they lay them together in communal masses. These masses can be so large that they may be above the water surface and be a meter long or more, looking like masses of caviar.
Tadpoles are eaten by water bugs, diving beetles, salamander larvae and herons etc. Other species such as introduced Bullfrog tadpoles and adults are believed to contribute to the decline of their populations because they share the same habitat.
Many other factors reduce their numbers as well. Loss of habitat is the biggest factor. Run-off from farmer fields (pesticides, fertilizers), siltation caused by grazing animals or development, acid rain and others all add to the problem. The Spotted frog seems to be more sensitive to these impacts than other frog species. In this way, they act like a "canary in the mine" to warn us of poor water quality in our area.
By the end of the summer, the tadpoles metamorphose to become froglets. You will see these small (2.5 cm or one inch) brown frogs hopping at the ponds edge.
If you find these frogs or their eggs do not remove or disturb them, note their exact location (mark it) and notify your state or provincial wildlife office. In the Greater Vancouver Area, B.C., contact Ministry of Environment 1-604-582-5200 for information. Collection permits are issued only to authorized organizations or trained biologists working with the Ministry.
This year in B.C., The Ministry of Environment in conjuction with students, naturalist clubs and biologists are determining where and how many Spotted live in the area so we can monitor them in the future. Data collection methods that do not disturb the frogs are being used: visual counts in the daytime, eyeshine at night, playing taped calls while listening for a response and presence and size of egg masses. Some of the eggs that are found will be raised in captivity by the Greater Vancouver Zoo for release into clean suitable habitat. They have applied for and received the appropriate permits.
by Donna Hill
B.Sc. B.Ed. 2000
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