8 Don C. Forester and Richard Daniel 



In our study, individuals appeared evenly spaced around the mar- 

 gin of the pond. On only one occasion was a calling male seen invading 

 the calling territory of a conspecific. This occurred on 16 June, when, 

 after 1 night at the pond, Male 10 moved into the adjacent territory of 

 Male 1. The resident male moved 1.3 m counterclockwise and continued 

 to call for 3 nights before disappearing from the pond. The only other 

 example of an extensive spatial shift occurred on 13 June, when Male 5 

 moved 2 m counterclockwise in response to rising water, which inun- 

 dated his original calling site. This shift did not cause a change in the 

 calling territory of the adjacent male (Male 4), and Male 5 remained at 

 his site for an additional 13 days before leaving the pond on 26 June. 



Although we did not quantify intermale distance, such data are 

 available for the species. Turner (1960) performed nearest neighbor 

 analysis on a Louisiana population in December and April, and reported 

 mean isolation distances of 1.94 m and 1.71 m, respectively. 



Behavioral Observations. — Five of the 11 males monitored during 

 our study (observations were made on 18 nights during a 37-night 

 period) were observed to amplex a female. Male 4 successfully amplexed 

 two females over a 4-night span. Five of the six amplecting pairs were 

 observed within a 5-night period during mid-June. It is probable that 

 additional matings occurred but went undetected, for we were unable to 

 visit the pond every night and frequently departed while some males 

 were still advertising. 



The operational sex ratio at our study pond was skewed in favor of 

 the males (5.6:0.3). However, it is likely that we underestimated the 

 number of females present at the pond, and as a consequence we con- 

 sider our OSR value conservative. 



On three occasions during the course of our study, we had the 

 opportunity to observe male-female interactions leading to amplexus. A 

 summary of each follows. 



(1) 13 June 1975. Male 4 was calling from his territory. With the 

 exception of his pulsating vocal sac, he was hidden from direct view by 

 dense grass. As we watched, a large female hopped into the circle of 

 light. She appeared to be searching for the source of the sound. Her 

 behavior included short, circling hops coupled with periodic cocking of 

 her head from side to side. As the male continued to call, the female 

 became increasingly active, crawling on the grass tussock and actually 

 passing directly over the male on several occasions. Although the female 

 circled eight times, the diameter of the circles never exceeded 8 cm. This 

 sequence occupied just under 5 minutes and terminated when the male 

 quickly emerged and amplexed the female. She neither resisted the male 

 nor initiated contact with him. 



