(1) The American bullfrog , for example, discharges copious amounts of mucus when basking in the drying rays of the sun.(2) Her belabored breathing is indistinguishable from the sounds of nature, the bullfrog 's croaks and the insects' swarms.(3) We also ran into a bullfrog big enough to choke an egret, as you can tell from its photo.(4) The tadpoles of some species, such as the bullfrog , take as long as two years to metamorphose into young frogs.(5) In their native habitat, predators such as large water snakes, alligators, and snapping turtles keep adult bullfrogs in check, while fish slurp tadpoles.(6) The lake behind the house was filled with tree frogs and bullfrogs and cicadas and crickets.(7) And bullfrogs are just one of a number of amphibian species people have moved, either by accident or for some intended benefit.(8) Evidence from past studies shows that the presence of Anax induces a reduction in activity level of small green frogs and bullfrogs .(9) I conducted a field playback experiment to investigate whether territorial male bullfrogs assess the size of opponents based solely on size-related variation in fundamental frequency.(10) There was always some sound to be heard; the chirping of crickets, bird songs, bullfrogs croaking, and the crunching of leaves and pine needles underfoot.(11) We identified 5 bacterial species from the newts and 5 from the bullfrogs .(12) Some fisherman and froggers catch large catfish, turtles, and bullfrogs by hand, thus preserving an ancient art.(13) In southern Arizona the most common vertebrates found in bullfrogs are other bullfrogs , Schwalbe said.(14) The average masses of the small bullfrogs and green frogs were determined by weighing 60 haphazardly chosen tadpoles from the populations used.(15) The Service hopes to further investigate the relationship between the non-native bullfrogs and the garter snakes within the Central Valley region.(16) With all the senses tingling, you can hear the hippos at the watering hole; the croak of the bullfrogs ; smell the dank scent of the cooling earth and anticipate, with trepidation, a prowling lioness.