Species Potentially Present on the Helena National Forest 



Western Chorus Frog (Pseudacris thseriata) 



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 thiough 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 ai-e 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 mni in diameter. Tadpoles are brown/bronze and the eyes are 

 located on the sides of the head. 



Similar species: Pacific Chorus Frogs {Pseudacris regilla) have obvious toe pads and an eye 

 stripe ending at the shoulder. Recently metamorphosed Ranid frogs could be confused with 

 this species but the coloration differs and the tiny toe pads are lacking (often visible only with 

 a magnifying glass on small chorus frogs). 



Habitat and Habits: 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. Following breeding, these 

 frogs move into adjacent uplands and are rarely seen. In eastern Montana they breed in 

 temporary ponds and small lakes surrounded by prairie; in some 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 (Wlieeler and Wheeler 1966, Nussbaum et al. 1983). 



Surveying: Aduhs are easily sur\'eyed for, using their calls for identification during the breeding 

 season in the spring and early summer. During the breeding season, adults may also be seen 

 in the water, but their small size and habit of freezing or diving when disturbed makes 

 observation difficult; night surveys may be more productive. Egg masses are difficult to find. 

 Tadpoles may be seen in ponds during the day and can be sampled with a dipnet. 



Status: Common tliroughout the prairies of eastern Montana. Two reports of Western Chorus 

 Frogs were received for the HNF. One report was from the vicinity of McDonald Pass and 

 the other from a cow pond in the upper Jackson Creek drainage of the Elkhorn Mountains 

 (Appendix 4); given the distance from other known locations and unusual habitat, these 

 report should be treated as hypothetical until verified. It seems possible that Western Chorus 

 Frogs will eventually be verified from the lower elevations of the HNF. The most likely 

 locations would be the extreme northeastern portion of the main Rocky Mountains east of 

 Lincoln, the east side of the Big Belts, or the Dry Range. 



Montana Natural Heritage Program rank: 05 S5. 



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