Pacific Chorus Frog {Pseudacris regilla) 



Description: Adults have a dark conspicuous eye line extending from the nostrils to the 



shoulder. Basic coloration is quite variable with the background color being green, brown, 

 gray, reddish or bronze. Dark spots and stripes often occur on the head, back, and legs. Most 

 have a dark Y or triangular shaped spot on the head between the eyes. The adult has a snout- 

 vent length of 0.75-2". Males have a darker throat color and additional folds of skin in the 

 throat region. This is the only frog in Montana with a combination of obvious toe pads and an 

 eye stripe ending at the shoulder. The webbing on the hind feet is very reduced, covering 

 only about 1/2 the length of the toes. Eggs are laid in small clusters of 10-70. The tadpoles 

 are brown/bronze; the eyes are located near the margin of the head when viewed from above, 

 unlike other frog tadpoles in western Montana which have the eyes are on top of the head 

 (except northern chorus frogs, Pseudacris triseriata, which also have the eyes at the margin 

 of the head). 



Habitat and Habits: Pacific 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 they 

 move into adjacent uplands and are rarely seen. In western Montana they breed in temporary 

 ponds in lower elevation forests and in intermountain valleys shortly after snow-melt. During 

 the 1993-94 survey, individuals of this species were observed or heard calling at 8 sites 

 throughout the Forest. Tadpoles were found at 3 sites on 20 Aug 94 at a pond near Blue 

 Lake, 30 July 93 at a pond near Trout Creek, and with froglets just emerging on 3 Aug 93 at 

 Tuscor Hill Pond. In the Pacific Northwest, eggs hatch in 2-3 weeks and tadpoles take 2-2 

 1/2 months to metamorphose, depending on water temperature (Nussbaum et al. 1983). 

 Transformed froglets grow quickly following emergence and in Oregon some were sexually 

 mature at 1 year (Nussbaum et al. 1983). 



Surveying: Adults may be found during the breeding season in and around ponds and lakes 

 where they breed. Adults are usually heard before they are seen. Adults may call 

 sporadically throughout the summer and fall, especially during wet, warm weather. Tadpoles 

 are seen in the water during the day. 



Status: Little is known about this species in Montana. Our surveys indicate very localized 

 distribution over a large area. Whether this has always been the case, or whether the Pacific 

 chorus frog is another declining Montana amphibian is currently unclear. 



Montana Natural Heritage Program rank: G4 S4. 



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