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How to Identify Male & Female Bullfrogs

The American bullfrog (Rana catesbeiana) is the largest species of frog native to North America. The American bullfrog's range includes the entire eastern half of the United States, as well as parts of extreme southeastern Canada. The frog's introduction to far western areas of the continent was successful, with the amphibian established in states such as California, Washington and Oregon. Although the male and female bullfrogs are very similar in appearance, two subtle differences allow you to tell them apart.

Instructions

- 1
  Look for a large frog. According to National Geographic, the American bullfrog can grow up to 8 inches in length. Both the males and females reach the same lengths and both can weigh up to 1 1/2 lbs.
- 2
  Inspect the head of the frog. Bullfrogs have a broad and flattened head, according to Dallas-Fort Worth Urban Wildlife. The head tapers at the nose to a round point. Bullfrog eyes appear large in comparison to the head and have a bulbous look. The irises of the eyes possess a golden or brown shade, while the bullfrog's ears take the form of a pair of circular spots on each side of the head, behind and below the eyes.
- 3
  Observe the color of the bullfrog, which is essentially the same on both sexes. The bullfrog has brownish or green skin, with the legs and back frequently marked with darker blotches and stripes. The belly is creamy white in color.
- 4
  Examine the hind and front legs of both sexes of the American bullfrog, looking for obvious differences in their lengths. The hind legs are much longer than the front ones, giving this frog the ability to complete jumps as long as 6 feet. Look for only the longest toe on each foot to lack webbing.
- 5
  Study closely the ear of the bullfrog to determine its sex. The outer ear (tympanum) is larger on the male, but only slightly. The frog is usually a male if the outer ear has a larger diameter than the frog's eye; conversely, the female's ear is normally smaller than the width of the eye.
- 6
  Identify the male from the female bullfrog by the color of the throat, but only during the frog's mating season. In northern parts of the bullfrog's range, the mating season lasts from May through July. In southern states, the mating season is much longer -- from February to October. The male's throat is yellowish during this time, but the female's throat is whitish.

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