sentence: Bullfrogs are more active at night.
sentences_before: Bullfrogs in northern United States hibernate during the winter time. They hibernate in mud at the bottom of ponds and rivers. They can breathe under water as long as they can get oxygen through their skin. They can also close their nostrils when they are under water. While hibernating, bullfrogs can slow their heart rate and metabolism down.
sentences_after: During the day, bullfrogs may rest under vegetation. Bullfrogs are an important food source for other wildlife, they provide protein for them. If there is a drought, bullfrogs will leave their habitat. During a rainstorm, they move quicker and are seen in large groups.
concept_name: bullfrog
headings: Bullfrog Habitat and distribution
categories: Frogs Symbols of Oklahoma