PARENT SESSION
Contributed Oral Session 48: Landscape Ecology: Animal Dynamics
Tuesday, August 9, 8:00 AM - 11:30 AM, Meeting Room 520 B, Level 5, Palais des congrès de Montréal
Matrix Permeability and Patch Occupancy by an Endemic Dispersal Limited Bird.
Darnell, Traci*,1, Sieving, Kathryn1, 1 University of Florida, Gainesville, FL, USA
ABSTRACT- We conducted a translocation experiment and developed a predictive model of population persistence for the Chucao Tapaculo (Scelorchilus rubecula), an understory-insectivore endemic to South American temperate rainforest. The translocation experiment was designed to test relative permeabilities of matrix components to movement. Radio-tagged Chucaos were translocated (individually) to three landscape-treatments consisting of small release patches that were either: (1) entirely surrounded by open habitat, (2) entirely surrounded by dense shrubs, or (3) linked to other patches by wooded corridors that were otherwise embedded in open matrix. The number of days subjects remained in release patches prior to dispersal was significantly longer for patches surrounded by open habitat than for patches adjoining corridors or surrounded by dense shrubs, indicating that dispersal was constrained by open matrix, but occurred equally well through corridors and dense secondary vegetation. However, the significance of dispersal limitation for population persistence remained unclear. Thus, patch occupancy data from two landscapes that differed in duration and degree of fragmentation were used to identify relevant landscape parameters, and to develop predictive models of population persistence. Patch area and landscape-context were important factors in both study areas, but different occupancy-thresholds were apparent. Overall occupancy was lower and larger unoccupied patches were observed in the landscape with longer fragmentation history and more extensive forest loss. It was impossible to dissociate the influences of several potentially important factors (e.g. total forest area, patch isolation, land-use history, and habitat degradation). However, we treated the study areas as two points along a continuum of land-use intensification, which we incorporated into a model for predicting Chucao persistence in landscapes at intermediate levels of fragmentation.
Key words: matrix permeability, patch occupancy, connectivity, Chucao Tapaculo