Thesis

Seasonal activities, homing, and orientation in the California toad (Bufo boreas halophilus)

In the spring, adult toads move several hundred meters from the surrounding hills to the breeding site in Seminole Lake to spawn, commonly swimming more than 80 m across the lake to the breeding congress. When artificially displaced from the breeding area and followed with a trailing device, toads quickly returned; on clear nights the return movement was direct, but under overcast skies they first moved to the nearest water and then along the shore to the breeding site. Tested in an orientation arena, toads oriented using celestial and auditory cues. However, blinded toads homed directly after displacement even when there was no calling. Anosmic animals appeared unable to orient accurately, thus, olfaction seems to be a key sense in guiding the toads' movements. Auditory cues, visual landmarks, celestial cues, learned travel routes, kinesthetic sense, geotaxis, and hygrotaxis were apparently necessary as cues for orientation in this toad.

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