Social Behavior of Acris gryllus 1 



Males were located by entering the pond at a given point each night and 

 searching the periphery from the water. When a male was located (usu- 

 ally by phonotaxis), a small marker was inserted into the substrate 

 beside him. The markers were constructed from wooden dowels (D = 3 

 mm, L = 120 mm) to which a piece of white, waterproof tape had been 

 attached. The identification number of the male and the observation 

 date were printed on the tape with India ink. Calling males apparently 

 were not disturbed by these activities. 



Site Fidelity by Calling Males. — Each time the position of a calling 

 male was marked, we recorded its spatial relationship (directional angle 

 and distance in cm) to the most recently placed marker and to the origi- 

 nal observation point. These measurements enabled us to plot the terri- 

 tories of individual males on graph paper. A Leitz planimeter (Model 

 3651-30) was used to calculate the area within each territory. Area 

 values were based on an average of five separate measurements. 



Statistical Analysis. — Spearman's rank correlation procedure (Zar 

 1974) was used to test for correlations between territory size and the 

 number of nights a male was observed at the pond, and between terri- 

 tory size and mating success. The Spearman's rank procedure is a non- 

 parametric test developed to process data obtained from a bivariate 

 population that violates normalcy. 



Operational Sex Ratio. — We calculated the operational sex ratio 

 (OSR) for the males and females observed during this study. The OSR 

 is defined as the average ratio of fertilizable females to sexually active 

 males at any given time (Emlen and Oring 1977). The OSR may or may 

 not reflect the overall sex ratio of the species, particularly for prolonged 

 breeders in which females arrive asynchronously at the reproductive 

 site. 



RESULTS AND DISCUSSION 



Site Fidelity and Size of Territory. — Individual males moved an 

 average of 52 cm (0 to 205 cm) between nights. Table 1 compares the 

 mean nightly movement of each male. Nine of eleven males were 

 observed on enough nights to facilitate calculation of their calling terri- 

 tories. Mean territory size was 0.562 m 2 (0.028-1.362 m 2 ). We believe 

 that this restricted movement and site fidelity warrant acceptance of our 

 first hypothesis, that calling Acris gryllus males are territorial. We must 

 reject our second and third hypotheses. There was no significant corre- 

 lation between the size of a territory and the number of nights a male 

 was observed at the pond (two-tailed Spearman's Rho, r = -5.521, P > 

 0.05). Neither was there a correlation between territory size and mating 

 success (two-tailed Spearman's Rho, r = 0. 187, P > 0.05) (see Table 2). 



