Sun compass orientation of the northern cricket frog, Acris crepitans.

Summary When released in water at the centre of a circular pen 50 ft in diameter, northern cricket frogs ( Acris crepitans ) from shores of natural bodies of water oriented on a compass course (Y-axis) that bisected the home shore at rightangles. Frogs taken to the test pen in closed containers responded similarly to those moved in view of the sky, and Y-axis orientation was unaffected in individuals displaced 115 miles east in light-tight containers. Specimens from opposite shores oriented to their respective Y-axis, even when released simultaneously. When a large number of individuals was collected from one segment of shore line and held in darkness for periodic release during a 24-hr period, orientation persisted under the sun, moon, and/or stars. Cricket frogs held in darkness at a constant temperature for periods of 30 hr and up to 7 days exhibited a decline in accuracy of Y-axis orientation that culminated in a random pattern after 7 days. Apparently differences in phase synchronization between the frogs timing mechanism and local time were responsible for the failure to orient. Orientation was reestablished to the original Y-axis by exposing ‘dephased’ specimens to the normal light-dark regime or to daily temperature and humidity fluctuations. A photo-period of normal duration, but administered 6 hr early (or late) relative to local time, reestablished orientation, but on a Y-axis 90° to the left (or right) of the original. A daily exposure to 10 min indirect light was sufficient to reestablish orientation in 8 days. A learned shore position, view of a useful celestial cue, and a timing mechanism phased to local time are necessary for Y-axis type of orientation. The demonstrated use of several types of temporal cues in the cricket frog suggests that alternative sources of information from several environmental components may be employed in nature, depending upon circumstance and availability. Y-axis type of orientation is a complex mechanism and appears to be a basic behavioural characteristic shared by most or all anurans