The snail kite (Rostrhamus sociabilis) is a wetland-dependent raptor whose entire U.S. population is restricted to the severely degraded wetlands of the South Florida Ecosystem. Habitat quality for this species is dependent on hydrology and wetland plant communities that support its foraging and nesting activities. Consequently, there is direct linkage between changes in hydrology and changes in habitat quality for the kite. In the recent past, there has been considerable interagency strife regarding the fate of kites and restoration activities in South Florida. This in conjunction with its Endangered status made it an ideal indicator species for restoration studies.
The principal thrust has been: 1) estimating population demographic parameters with an emphasis on survival, particularly as influenced by environmental variables such as wetland hydrology and habitat quality over space and time; 2) evaluating the movement patterns of snail kites in Florida, including rates, locations, and what environmental conditions are correlated with these movements; 3) estimating population trends over time, 4) developing a protocol for future monitoring; and 4) collaboratively participating in the development of an individually-based simulation model for tracking snail kite population responses to future restoration scenarios for the Everglades. The study area has been the entirety of the South Florida freshwater hydroscape. Radio-telemetry (280 individual birds, for within year responses, Kaplan-Meier estimator) and mark-resighting (approx. 900 banded birds, for between year responses, Cormack-Jolly-Seber model) techniques are being used to estimate demographic parameters, track movement patterns and estimate population size.
One of the most dominant and conspicuous features in the Everglades landscape is the presence of numerous "tree islands" interspersed in the vast mosaic of sawgrass strands and wet prairie matrices. The historic landscape of the Everglades was characterized by its 1) immense size, 2) extremely flat gradient and sheet flow, and 3) the continuous interspersion mosaic of wetland types and water depths. The system has been radically altered and reduced to approximately half its original size. Additionally, construction of dikes, canals, and water works has reverted the system outside the Everglades National Park to a set of vast impoundments (water conservation areas) that serve to store and release excess flows; thereby, completely fragmenting the system, severely eroding the interspersed mosaic, and regulating flows through structures that virtually eliminate sheet flow.
The question confronting restoration managers addresses how these impacts have affected various landscape features like the tree islands, and whether or how restoration alternatives might successfully restore such landscape elements. My students and I have engaged in studies of the relationships between tree island patterns and the influences of the hydrology and fire on these patterns for the past several years. We have employed remote sensing (trend analyses) and innovative spatial statistical techniques with GIS technologies to quantify landscape patterns (shape, size, orientation, contiguity, growth, etc.), and addressed hypotheses concerning the structuring influences of fire and hydrology through direct observation, and spatial hydrological and fire simulation models. This research has been conducted under my direction as principal investigator and graduate supervisor of two University of Florida Ph.D. students (Jennifer Silveira and Laura Brandt, both graduated), accounting for approximately 20% of my time. Funded by: Fish and U. S. Wildlife Service and USGS/BRD.