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Mountain Yellow-legged Frog (Rana muscosa) Fact Sheet: Physical Characteristics

Physical Characteristics

Snout/Vent Length* 2.20 inches (56 mm) 2.52 inches (64 mm)
Weight 0.74 ounces (21 g) 1.16 ounces (33 g)

*Relatively small frog: Snout/vent length is 1.5"-3" (from tip of snout to base of backbone to cloaca).
Snout vent length decreases as you move up in elevation.

General Appearance

Skin color and pattern

  • Variable skin pattern and coloration on back
  • Brown, yellow, gray, greenish-brown covered with dark spots and mottling
  • Throat white or yellow with mottling
  • Ventral surface of legs yellow
    • Juveniles may have less color

Eyes and tympanum

  • Iris is gold with horizontal black stripe
  • "Ears" (tympanic membranes) sense vibration as well as airbourne sound

Sexual Dimorphism

  • Females tend to be larger
  • Males with nuptial pads during breeding season
    • Extensions on forefeet
    • Allow male to grasp female during copulation


  • Breathing
    • Tadpoles have gills
    • Adult frogs have paired lungs
    • Can breathe through entire skin surface
      • Thin, permeable skin
      • Mucous-producing glands aid oxygen consumption and provide protection
  • Osmoregulation
    • Water absorbed through skin; drinking is unnecessary
    • Water is constantly expelled by kidneys
  • Skeleton has both bony and cartilaginous components

Mountain Yellow-Legged Frog

Mountain Yellow-legged frog in grass

Mountain Yellow-Legged Frog (Rana muscosa).

This frog carries a small radio transmitter, enabling researchers to track its movements.

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.

Page Citations

Mathews and Miaud (2007)
Wright and Wright (1993)
Lemm (2006)
Zweifel (1955)
Jennings and Hayes (1994)
Monnet and Cherry (2002)
Halliday and Adler (1986)

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