Degree Name

Master of Science (MS)

Semester of Degree Completion

2000

Thesis Director

Kipp C. Kruse

Abstract

The chemosensory capability and subsequent habitat choice of larval American toad (Bufo americanus) tadpoles were quantified using choice of refuge with both early and late developmental stages. Treatments were performed with two tadpole densities to ascertain the effect of social aggregations upon behavior. Bluegill (Lepomis macrochirus) and predaceous diving beetle larvae (Dytiscus sp.) predators were used to condition water. Conspecific tadpoles as well as Southern leopard frog (Rana sphenocephala) tadpoles were used to prepare treatment extracts.

Tadpole density (n=10 and n=20) had no significant effect upon the percentage of tadpoles seeking cover in any treatment. The percentage of toad tadpoles of early developmental stages seeking cover was significantly higher when exposed to both early and late staged conspecific alarm signals as compared to the control, however, the treatment responses were statistically indistinguishable from one another. Similarly, the presence of beetle larvae in test chambers elicited a strong fright reaction by tadpoles when compared to controls. Tadpoles responded more strongly to the presence of beetle larvae than to chemical cues of larval beetles. Likewise, the addition of bluegill cues elicited a significant antipredator response from toad tadpoles.

Late developmental stage toad tadpoles showed no significant increases in the percentage seeking cover in any treatment; these results are attributable to the high percentage of larvae seeking cover in control trials. My results suggest that tadpoles may display antipredator tactics that are stage-specific and geared toward differing suites of predators.

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