Date of Award

1981

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Abstract

Biotelemetry was used to study thermal and spatial relationships in Nerodia fasciata confluens, N. c. cyclopion, and N. r. rhombifera. Twenty snakes were monitored between April 1978 and September 1979 in Ascension Parish, Louisiana. Laboratory-determined preferred temperature ranges were compared to environmental temperatures from air, soil, and water to predict thermally optimum microhabitats. Comparison of observed and predicted microhabitats for each observation showed that N. fasciata was found more frequently in the thermally optimum microhabitat than were N. cyclopion and N. rhombifera. Nerodia cyclopion consistently showed thermal nonconformity by altering the relationship between body (BT) and ambient (AT) temperatures so that BT was closer to the preferred range when AT was high or low. All species showed the highest degree of thermoregulation in spring/fall; the lowest degree of thermoregulation was found in summer for N. cyclopion, and in winter for the other two species. Snake movements showed a high degree of variation. Snakes typically stayed in a home area for about 20 days before making a major movement (> 100 m). Nerodia fasciata moved significantly more than N. rhombifera. The latter species stayed closer to land, spent more time underground, and, when in water, was found at greater depths than the other two species. The mean home range polygon for all observations was 5.96 ha, with values ranging from 0.03 to 15.39 ha. Home range size showed much variation and was not significantly correlated with species, sex, reproductive condition, weight, time of year, length of tracking period or interval between observations.

Pages

158

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