Western Chorus Frog (Pseudacris triseriatd) 



Description: Adults are very small (0.75-1 .5") and have tiny, almost unnoticeable toe pads. 



They have a dark line extending from the snout through the eye to the groin. Basic coloration 

 is quite variable with the background color being green, brown, gray, or reddish. Typically 3- 

 5 dark longitudinal stripes are present on the head and back which may be broken up into 

 spots on some individuals. 



Eggs and Tadpoles: Eggs are laid in small clusters of 10-100, usually less than 1 " across and 

 attached to submerged vegetation (Wheeler and Wheeler 1966, Baxter and Stone 1985). 

 Individual eggs are about 1 mm in diameter. Tadpoles are brovm/bronze and the eyes are 

 located on the sides of the head. 



Similar species: Recently metamorphosed Ranid frogs could be confused with this species but 

 the coloration differs and the tiny toe pads are lacking. 



Habitat and Habits: Adult Western Chorus Frogs are regularly found in the water only during the 

 breeding period in spring. Their presence is obvious during this time due to their call which 

 is given frequently at night and sporadically throughout the day. Calls were heard on the 

 study area during surveys in late-May; however, the precise beginning and end of the calling 

 season in the area is unknown. They had apparently not yet laid eggs by late May, but any 

 tadpoles that were present had metamorphosed by mid-August. Following breeding, these 

 frogs move into adjacent uplands and are rarely seen. Western Chorus Frogs were foimd on 

 the study area in ponds located both in the prairie and open-forest habitat. Throughout 

 eastern Montana they breed in temporary ponds and small lakes surrounded by prairie; in a 

 few other locations in Montana they are also found in open forested habitats. Eggs hatch in 

 about 2 weeks and tadpoles are about 2 months old at metamorphosis (Wheeler and Wheeler 

 1966. Nussbaum at al. 1983). 



Status: Western Chorus Frogs appeared to be the most common amphibian on the study area. 

 They can be expected to occur in most ponds in prairie habitat, and at some ponds within the 

 forest matrix, becoming rapidly less common to the west. None are known to occur in 

 forested habitat more than 1 km from the prairie-forest ecotone. Common throughout the 

 prairies of eastern Montana. 



Montana Natural Heritage Program rank: G5 S5. 



