PARENT SESSION
Oral Session #74: Spatial Ecology: Models and Methods. Presiding: C. Loehle.
Friday, August 10, 2001. 8:00 AM to 11:30 AM. Hall of Ideas E.
Estimating dispersal kernels from mark-recapture data.
FUJIWARA, MASAMI1,2, NEUBERT, MICHAEL1, CASWELL, HAL1, 1 2
ABSTRACT- We present a new method for estimating a distribution of dispersal displacements (i.e. a dispersal kernel) from mark-recapture data. One conventional method of calculating a dispersal kernel assumes that displacements are normally distributed (e.g., resulting from a diffusion process) and that individuals remain within sampled areas. The first assumption prohibits the analysis of dispersal data that are not normally distributed (a common situation); the second assumption leads to underestimation of dispersal distance because individuals that disperse outside of sampling areas are never recaptured. Our method eliminates these two assumptions. The new method uses integral equations to express the probability of spatial mark-recapture data; associated dispersal and recapture parameters are then estimated using a maximum likelihood method. We also incorporate mortality and stage-transitions that occur over a longer time scale than the dispersal process using a "robust design" approach. Our method will allow reexamination of existing data sets and suggest designs for future mark-recapture experiments that will allow for estimation of mortality and stage-transition rates as well as dispersal kernels.
KEY WORDS: mark-recapture statistics, dispersal kernel, distribution of dispersal displacements , integral equations