The study of social animal migrations: a synthesis of the past and guidelines for future research

Abstract

Seasonal migration is a common behaviour seen in many species worldwide. There is evidence that social factors influence various migration decisions, but compared to the well-studied field of social foraging, the study of social animal migration is still underdeveloped. Nevertheless, a few innovative studies have shown the impact of social influences on migrating animals using different tools and techniques. In this review, we systematically examined the literature to identify what makes a strong study in the field of social animal migration. We synthesized existing literature to provide advice that can improve study design and the conclusions drawn for future studies on social migration. Our analysis revealed that social interactions are widely studied among migrating species. We identified methods and approaches that, when combined correctly, provide strong evidence of social influences during migration. Finally, based on the strengths and shortcomings of past studies, we propose a set of guidelines to create more robust studies on social animal migrations.

Keywords: migration decisions; seasonal animal migration; social influences; systematic literature review.

Figure 1.

An overview of the taxa and of the social processes and migration decisions that have been studied in the past, as well as the methods that were used. (a) The number of studies per taxonomic group, and the colours indicate the study type. (b) Connections between social processes and migration decisions, with the width of connections being indicative of the number of studies. (c) The number of studies that used a certain method (middle) to study social processes (left) and migration decisions (right), with colours corresponding to the different categories.

Figure 2.

Quantification of studies in terms of the number of methods used and the different axes of scientific robustness. (a) Relationship between the quantification of social influence and the number of methods used. The circle area and numbers inside the circles represent the number of studies that fall into the respective categories. Colours represent the categorization of the quantification of social influence. (b) Relationship between hypothesis testing, the inferential approach and quantification of social influence. The circle area and numbers inside the circles represent the number of studies that fall into the respective categories. Colours represent the categorization of the quantification of social influence. (c) Case studies identified via a systematic review were placed within our classification of scientific robustness (i.e. quantification of social influence versus inferential approach). Sample sizes within each box represent a number of studies that fall into the respective categories.