Boreal Chorus Frog. Pseudacris maculate

Description: Adult: A small frog with a head and body length of 20-40 mm. Overall build is gracile, with a relatively long body. The snout is pointed, the eyes are prominent and the tympanum is smaller than the eye. The toes are relatively long and do not bear terminal pads. The toes of the hindfoot are feebly webbed. The skin is granularly textured. Colour is highly variable with the background colour ranging from grey to brown to green. A dark stripe extends from the snout, through the eye to the groin. The upper jaw has a white stripe. There are usually three, often broken, irregular dark longitudinal stripes on the back. There is often a pale, triangular patch between the eyes. The venter may be white, yellow or a diffuse olive colour, with few or no dark markings.

Larvae: Tadpoles hatch at about 4-7 mm total length and reach about 30 mm. Froglets are 7-12 mm long just after metamorphosis. The tadpole's labial teeth are 2/3. Tadpoles are dark olive to black above and silver with a coppery sheen below. The eyes are more or less lateral. The dorsal fin is greatly arched and lightly to moderately pigmented. The anus is dextral and the spiracle sinistral.

Variation: Males have a greenish throat and a single, rounded vocal sac, and are slightly smaller than females. Males develop a nuptial pad on the first finger in the breeding season.

Natural history: This species frequents grassy pools, lakes, marshes and almost any other body of water. It occurs on farms and in cities, where suitable habitat is present, except in areas where pesticides are heavily used. It eats ground-dwelling insects, snails, millipedes and other small invertebrates. Larvae are taken by diving beetles and other aquatic predators. Its habits are little known outside of the breeding season. It may spend the non-breeding season in damp marshy or woody areas and overwinter in relatively dry sites. Individuals may climb into low vegetation. When moving on the ground, they hop.

Reproduction: Breeding usually occurs in April to June. It will breed in almost any body of water, both shallow and deep. Males begin to call before the snow melts. During the height of the breeding season calling may occur both night and day. Males usually call from concealed sites. Amplexus is pectoral. Eggs are laid in small clumps attached to vegetation. From 150 to 1500 eggs are laid over a number of days. Each egg is about 1.0 mm in diameter. They hatch in ten to fourteen days. Development and metamorphosis occur in about two months. Individuals reach maturity and breed in the following year, and they do not live to breed for a second season.

Voice: A terminally inflected trill of short duration (1-1.5 seconds). Such trills may be strung together in continuous phrases. The sound produced is much like that generated when one's finger is run along the teeth of a stiff plastic pocket comb.

Distribution: The boreal chorus frog occurs throughout the province, except in true alpine habitats. Extralimitally, it is found from west central Northwest Territories east to southern James Bay and south to the upper mid-west and Great Plains states as far as northern New Mexico and Arizona.

Conservation status: The boreal chorus frog shows no signs of decline across its broad range in Alberta.

Remarks: Although some authors refer to this taxon as Pseudacris triseriata maculata, Collins (1997) affords it full species status.

Significant references: Bleakney 1959; Brown, L.E. and Pierce 1967; Dunlap 1980; Gaudin 1974; Kramer 1973, 1974; MacArthur and Dandy 1982; Matthews 1971; Mosimann and Rabb 1952; Roberts and Lewin 1979; Smith, D.C. 1983; Smith 1956; Travis 1981; Wassersug and Sperry 1977.