The Effect Of Fix Rate And Fix Interval On First Passage Time Analysis

Scientific Disciplines
Biological Sciences - Terrestrial
Mathematics, Statistics & Computer Science
Montana State University
Greater yellowstone ecosystem
fix interval
scale movement
spatial scale
passage time analysis
Volume 17, No. 1-4

The effect of fix rate and fix interval on first passage 
Time analysis
Kurt A. Michels,* Department of Mathematical Sciences, Montana State University, Bozeman, 
Montana 59717,
Steve Cherry, Department of Mathematical Sciences, Montana State University, Bozeman, Montana 
First passage time analysis is a method of analyzing changes in animal movement along 
paths through habitats. First passage time is defined as the time required to traverse a circular 
region of a specified radius. Plots of variance in logged first passage times versus spatial 
scale have been used to help identify the scale at which search is concentrated. Two critical 
assumptions made when calculating first passage time are that movement is linear and speed 
is constant within a given circle. We investigate the robustness of first passage time results 
relative to these 2 assumptions using movement data collected on eight grizzly bears in the 
Greater Yellowstone Ecosystem. We found that the spatial scale identifying area restricted 
search was dependent on both fix interval and fix rate suggesting that how GPS collars are 
programmed influences first passage time results.