Migration quantified: Constructing models and linking them with data

Abstract

This chapter discusses how models, combined with modern data sources and statistical methods, can be used to test different hypotheses about the causes of migration. It presents mathematical formulations for migration and discusses the ecological mechanisms that could spontaneously have given rise to migration-like patterns of space use from the interaction within and between groups of animals and their environment. This highlights that migration is best seen as lying on a continuum from sedentary to nomadic movement patterns and not as a clearly distinct movement behaviour. Given the multitude of potential processes leading to migration, and the constraints imposed by data collection methods, it may be difficult to observe and identify the original cause. With this caveat in mind, the use of inferential methods to detect, quantify, and identify the underlying mechanisms of migration is discussed, and the links between models, data, and inference are illustrated using three case studies.