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Report an Invasive Species

American Bullfrog

American Bullfrog

American Bullfrog

(Lithobates catesbeianus)

Tags: Aquatic

Identification and Reproduction


  • American bullfrog has a large robust body that can reach 20 centimeters in length. 
  • They are green or brown in colour and have yellow or pale cream to white throats.
  • The baritone call of the bullfrog is so deep and resonant, it resembles the mooing of a cow.
  • Only males emit this trademark "jug-o-rum" bellow, and their choruses can be heard during the day or night during mating season.
  • Look for: the circular “ear drums” on the side of the head behind their eyes.


  • This species breeds from the late spring to early fall. 
  • Males are territorial. Mating success is influenced by the quality of the territory.
  • Females lay one or two clutches per season with average clutch size is 12,000 eggs.
  • Clutches are laid in a film on the water surface with eggs hatch in approximately 5 days. 
  • Tadpoles can be very large, 125-150 mm.
  •  Metamorphosis usually takes 1 year, larvae will overwinter in ponds and larval survivorship is about 18%. 
  • This species typically reaches sexual maturity one year after metamorphosis .

Habitat & Ecology

  • They are among the most wide-ranging of all North American amphibians, found in freshwater ponds, lakes, and marshes.
  • Average lifespan in the wild is 7 to 9 years
  • Can grow up to 1.5 lb and 20 cm long. 


  • American bullfrogs displace native frogs in habitats they invade by outcompeting and depleting the food sources of native frogs.
  • Causing decline in the native red-legged frog and pacific chorus frog populations.


  • Do not move any tadpoles (regardless of species), and do not move frogs from one waterbody to another - this helps them spread.