Understanding encounters data, based on the interactions that produce them

Encounter data in resource management and ecology: pitfalls and possibilities

Aidan Keane,Julia P. G. Jones,E. J. Milner-Gulland¹

Article first published online: 13 JUN 2011

Journal of Applied Ecology

Volume 48, Issue 5, pages 1164–1173, October 2011

 

Simple indices based on the number of encounters are ubiquitous in conservation practices. This encounter data comes through the interaction of two sets of behaviours, i.e. those of the data generators and those of the data collectors. When these behaviours do not conform to the assumptions used to model, analyses of encounter data may go haywires

The researchers here review the use of CPUE indices derived from patrol data, which have been promoted for the study of rule-breaking in conservation. They highlight potential sources of bias and mention how similar problems have been tackled for other forms of encounter data. 

The researchers identify several issues that must be addressed for analyses of patrol data to provide useful information. This includes the definition of suitable measures of catch and effort, the choice of appropriate temporal and spatial scales, the provision of suitable incentives for ranger patrols and the recording of sufficient information to describe the spatial pattern of sampling.

In short this paper describes a common conceptual framework for understanding encounter data, based on the interactions that produce them. The researchers anticipate that an appreciation of these commonalities will lead to improvements in the analysis of encounter data in several fields, by highlighting the existence of methodological approaches that could be more widely applied, and important characteristics of these data that have so far been neglected.