Sun-compass orientation in the treefrogs, Hyla crucifer and Pseudacris triseriata triseriata

Sun-compass orientation tests were performed on adults and larvae of the spring peeper (Hyla crucifer) and the western chorus frog (Pseudacris triseriata triseriata). All animals were tested outdoors in a circular test pool from which all visible landmarks were obscured. Response on the Y-axis varied with the life history stage, and significant interspecific differences in sun-compass orientation behavior were noted. Statistical analysis was performed with Batschelet's V-test.Adult frogs were captured as they migrated to the breeding pond and tested under sunny skies. Chorus frogs oriented on the deep-water Y-axis of the nearest shoreline (n=30, p <0.005) but spring peepers did not orient (n=42, p >0.10).Frogs were also captured in the breeding pond at weekly intervals throughout the breeding season and tested under sunny skies. Chorus frogs oriented toward shore on the Y-axis (n=45, p <0.005); spring peepers did not orient (n=96, p >0.10). Adult chorus frogs kept in outdoor enclosures for a month after the breeding season were still oriented toward shore on the Y-axis (n=6, p <0.05). Chorus frogs tested under sunny skies after ten days of constant temperature, dim-light conditions in the laboratory did not orient (n=10, p >0.10).Adult chorus frogs captured as they left the breeding pond and tested under sunny skies did not orient on the Y-axis of the nearest shoreline (n=33, p >0.10), and neither did spring peepers (n=38, p >0.10).Larval western chorus frogs raised in outdoor enclosures oriented toward deep water on the Y-axis within five days after hatching (n=29, p< 0.005) and during late premetamorphosis (n=33, p <0.001). Chorus frog larvae did not orient during mid-premetamorphosis (n=32, p >0.10). Newly metamorphosed juveniles oriented on the Y-axis toward shore within a week after emergence (n=25, p< 0.01).Larval spring peepers oriented on the Y-axis toward shore within 18 days after hatching (n=37, p <0.0001) and also late in metamorphosis (n=29, p< 0.0001). Newly metamorphosed juveniles were not tested.