The Bullfrog, Rana catesbeiana Shaw. 77 



LIFE-HISTORY OF THE BULLFROG. 



Because of its size, appetite, vocal accomplishments, and supposed shy- 

 ness, this species has received more attention than any other American 

 member of the genus Rana. In the northeastern United States, it can 

 be confused only with the green-frog. In common, they have the tym- 

 panic disc as large as (in females) or larger than (in males) the diameter 

 of the eye ; and the throat is yellow in the males. Unlike the green-frog, 

 the lateral folds are absent, and the web of the fourth toe extends to 

 its tip. 



One commonly associates the bullfrog with marshy bayous, button- 

 bush swamps, mill-ponds, or lakes. They are not, however, so re- 

 stricted in habitat as some texts might lead the reader to infer. I 

 have found them along both upland and lowland streams, in clear 

 brooks which fed cold, marly, sphagnum ponds, and along water- 

 courses laden with such marshy vegetation as lizard's-tail, marsh-cress, 

 arrow-head, pickerel- weed, and swamp-loosestrife. Rarely they have 

 appeared in small numbers in temporary or very small ponds a more 

 logical home for the green-frog. Such distribution can ordinarily 

 be explained by the loss or draining of a former mill-pond or reser- 

 voir habitat nearby, and such records are more accidental than 

 normal. Occasionally one finds them assembled in large numbers in 

 very small circumscribed areas, due usually to some catastrophe or 

 drought. In one instance, on June 16, 1913, we discovered that the 

 water-space in a cat-tail swamp had shrunk to a hole 10 by 10 feet and 

 therein were gathered the whole swamp's colony of bullfrogs, some 25 

 or 30 adults. They seem to prefer mill-ponds, hydraulic lakes, reser- 

 voirs, and kindred bodies of water. Our best collecting-grounds were 

 a clear glacial lake in a kettle-hole with a slight suggestion of the sphag- 

 nous flora about it ; a pond in a clear trout-brook ; a large reservoir for a 

 hydraulic laboratory; a disused mill-pond; and a wooded lake whose 

 shifting water-level had made a fringe of overhanging dead trees, floating 

 logs, and submerged roots and limbs. In every case the shores are more 

 or less wooded, but more important are two other factors: shallows 

 where the species can transform; and brush, stumps whose roots are 

 at the edge of the pond or overturned, and driftwood along the banks. 



THE FIRST APPEARANCE. 



Rana catesbeiana is our last Anuran to emerge from hibernation, fol- 

 lowing three weeks after the tree-toad, which is then beginning the 

 chorus-stage. When the bullfrog comes out, the first five species to 

 appear in the spring are entirely or almost finished with their spawning. 

 The bullfrog is such a wary form that in some years its presence is not 

 suspected until June, when croaking begins. Our first records are shown 

 in the table at top of page 78. From this, either for the day previous 



