Vertebrate Research

Project Director: James N. Layne

[Biennial Contents | Biennial 95-96 | Research]

During 1997–98, I continued a study of longterm trends in the vertebrate fauna, with emphasis on small mammals, of oldgrowth southern ridge sandhill habitat on the Station’s Red Hill. Although this vegetation type normally burns every few years, the Red Hill stand is unusual in that it has not burned for 70 years, affording a unique opportunity to document the effects of prolonged absence of fire on the vertebrate community and other ecological characteristics of this habitat. Initial observations were made in the late 1950s, and since 1968 the species composition and abundance of mammals and other vertebrates on two 2.7-hectare grids have been systematically monitored at periodic intervals. Data also have been obtained on trends in vegetation, microclimate, and mast production. In 1993, one of the study grids was prescribed-burned (see photos, page 27) and the other left unburned as a control. The extensive preburn database has provided both a more detailed knowledge of the trends in the vertebrate fauna in a normally fire-prone habitat in the prolonged absence of burning as well as a solid baseline for evaluating the impact of the reintroduction of fire into the habitat.

     One of the general results of the vertebrate study is the finding that most species, such as the sand skink, gopher tortoise, Florida mouse, and oldfield mouse, characteristic of open sandhill habitats maintained by burning at normal intervals can survive for long periods in the absence of burning, apparently due to the persistence of open patches in the shrub understory. In the case of small mammals, a somewhat unexpected result of the prescribed burn was that while there was the predicted increase in relative abundance of oldfield mice and Florida mice and decrease in cotton mice and golden mice, which are characteristic of more densely wooded habitats, actual numbers of the former species were less than in some years during the preburn period. The most conspicuous change in bird species composition of the sandhill study site has been the disappearance of the Florida scrub-jay in the oldgrowth phase by the early 1970s and its reappearance on the burned grid by 1997, 4 years post-fire. It should be noted, however, that the scrub-jay is not a characteristic species of typical sandhill habitat, its presence in the southern ridge sandhill on Red Hill probably being attributable to the invasion of that habitat by scrub oaks in the absence of fire.

     Other projects. In addition to field work associated with the above project, I participated with Research Affiliates Walter Meshaka and Jerry Johnson in preparation of a manuscript on a 17-year study of amphibians and reptiles on a pitfall grid in another oldgrowth ridge sandhill habitat on the station and with Research Associate Warren Abrahamson  on a manuscript dealing with patterns of acorn production in five species of oaks in relation to size, habitat, topography, and weather factors over a 27-year period—one of longest datasets for mast production on record. During spring 1998, I cooperated with the Florida Game and Fresh Water Fish Commission in monitoring movements and habitat utilization of a radio-collared male Florida panther in Highlands and Polk counties. This was the first documented case of dispersal from the Big Cypress region across the Caloosahatchee River into central Florida.

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