Abstract

Multistate release–recapture models are used to study the movements and survival of animals when multiple migration pathways exist. Model complexity increases exponentially as the number of possible migration pathways increases. Program Branch was developed as freeware to allow users to construct multistate release–recapture models based on a schematic of the study design built with a graphic user interface (GUI). The GUI can be used not only to develop the underlying statistical likelihood models but to direct the estimation of summary performance parameters. Program Branch is illustrated using the spawning behavior of shortnose suckers (Chasmistes brevirostris) in northern California, juvenile Chinook salmon (Oncorhynchus tshawytscha) outmigration through the Sacramento–San Joaquin Delta of California, and adult steelhead (Oncorhynchus mykiss) migration in the Columbia/Snake River Basin in the Pacific Northwest. This software, available online at http://www.cbr.washington.edu/analysis/apps/branch , makes the analysis of complex multistate models easier and allows investigators to review study designs to ensure important model parameters are estimable.

Highlights

  • Multistate release–recapture models are used to study the movements and survival of animals when multiple migration pathways exist

  • The purpose of this paper is to describe the use of digraph theory to translate schematics of multistate processes into maximum likelihood models

  • Survival was highest when the suckers were primarily in the Clear Lake Reservoir and lowest when in Willow Creek. These results suggest actions to protect this Endangered Species Act (ESA)-listed species may best be focused on improving survival in Willow Creek and its tributaries during the critical spawning period

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Summary

Introduction

Multistate release–recapture models are used to study the movements and survival of animals when multiple migration pathways exist. Release–recapture studies have been used to estimate the survival probabilities of wild populations for decades [1]. Brownie et al [2] developed a method to analyze the release–recovery data from bird banding studies of waterfowl populations. In these early singlestate models, all animals have the same probability of transition from event i to event i + 1 regardless of prior disposition. Animal survival may be a factor of Originally, release–recapture models were developed envisioning the physical recapture of the tagged animals to obtain survival information. The result is greater resolution of animal movements and survival without the concern that recapture and rehandling may alter animal behavior and violate model assumptions

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