Rana sphenocephala 425 



Aug. 9. 3:00 a. m. Heard a large chorus early this morning. 4-5:00 a. m. 

 another chorus in Coat Bet Pond. 

 " II. Plenty in chorus in Coat Bet Pond 1:30 a. m. Air about 72°. 

 " 20. Chorus before daybreak in Coat Bet Pond. 

 " 22. Same. 

 " 29. At dusk and later a few croaking on prairie. 



In the 192 1 croaking record the temperatures for the day of croaking were 

 from 80-97° for maxima and 52-74° for minima. Most of our camp records 

 for the day time range from 66-79°. Most of the large choruses came during, 

 preceding or subsequent to large downpours of rain. On April 23, they were 

 croaking in chorus when the air was 58° F. and water 60°. Inasmuch as most 

 choruses came at night maxima probably play the most important role of 

 temperatures. The average for all minima for croaking days is 65°. No 

 doubt that or lower temperatures prevailed when southern leopard frogs 

 croak. Humidity is a more important factor than temperature. 



The croak itself comes from the swift inflation and deflation of the vocal 

 sacs (each between forelegs and angle of mouth). On April 23 we noted that 

 "the croak of a male sometimes is two croaks, often one or two lower croaks 

 or two or three. Males frequently give two or three clucking-like notes often 

 followed by two or three croaks. Whole performance no more than 4 or 5 

 seconds. On May 16 we wrote "The croak is 3, 4 or 5 croaks with two or three 

 clucks afterwards. The process may occupy 5 or 6 seconds." Mr. Harper 

 characterizes the croak as follows: "The frog may commence with a series of 

 guttural grunting croaks: wank-wank-wajik, ... As a whole chorus tunes 

 up and the clamour increases, the notes become louder and take on a more 

 rattling quality: wonk-wonk-wonk. They are easily heard a quarter of a 

 mile, . . ." 



MATING 



Male {From life, July 3, 1921.) Olive green or jade green or grass green on 

 back, pale chalcedony yellow on upper lip, pale dull green yellow costal fold; 

 center of tympanum chalcedony yellow. Some amber yellow or primuline 

 yellow on under side of fore arm or httle on the side of the groin, little on 

 outer side of hind legs and back of crus. Under parts white. Thumb with 

 black swelling. Iris: back part chartreuse yellow; upper part vinaceous buff; 

 inner ring amber yellow or wax yellow; rest black. 



Female {From life, June 21, 1921). Top of head to back of eye cinnamon 

 brown to Front's brown or snuff brown to bister or sudan brown to brussels 

 brown. This color somewhat along inner and outer side of the costal fold, on 

 upper jaw from snout to front of eye somewhat on upper fore limb and some- 

 what amongst ground color of back. At times it makes most of the ground 

 color of the back. Back ground color of dorsum dark greenish olive to ivy 

 green. Spots of back and sides, fore arms, shoulder bar, and hind legs, black. 

 Those of the back with a thin hght green yellow border. Under parts white. 

 Throat and pectoral region dulled with blackish. Lower jaw rim marguerite 

 yellow or sea foam yellow with black. Same color for upper jaw below the 

 stripe from lower eye to arm insertion. Between the sudan brown of the side 



