What Can We Quantify About Carer Behavior?

James L Savage,Camilla A Hinde

doi:10.3389/fevo.2019.00418

Abstract

In many species, individuals must contribute extensively to offspring care to reproduce successfully. Within species, variation in care is driven by local social, physiological, and environmental contexts, and this relationship has been a major focus of behavioral ecology since the inception of the field. The majority of existing studies on care, both theoretical and empirical, have focused on measuring the amount of care delivered by each carer as a proxy for individual investment, linking this investment to the local context, and investigating outcomes for offspring. However, more recently interest has grown in the finer-scale details of care, including how individuals respond to each other’s behavior, and temporal variation in care both within and between stages. Simultaneously, advances in remote monitoring methods, such as video cameras and passive integrated transponder (PIT) tag systems, have vastly increased the ease of collecting large amounts of care data, providing opportunities to study carer behavior in much greater detail than previously possible. In this mini-review we provide an overview of the dimensions of carer behavior that can be quantified, illustrated using recent studies from a variety of taxa. We classify these analyses into three broad groups: (a) how parental care is distributed in time, (b) variation within care events, and (c) how carers interact when jointly providing care. Our aim is to encourage more in-depth analyses of parental care, to build a more complete picture of how animals rear their offspring.

Highlights

Parental care often requires substantial investment of time and energy, and strongly impacts the fitness of the individual carers that provide it (Saether, 1994)
Our review illuminates a number of questions that remain despite the vast literature on parental care
Aside from visit rates, we still know relatively little about how patterns of care are influenced by the ecological, environmental, physiological, and behavioral contexts of care

Summary

Introduction

Parental care often requires substantial investment of time and energy, and strongly impacts the fitness of the individual carers that provide it (Saether, 1994). Previous studies have shown that care behavior is influenced by individual characteristics such as sex (Liker et al, 2015), age (Ortega et al, 2017), condition (Dearborn, 2001), and personality (Westneat et al, 2011). Many studies only measure the amount contributed by each carer within one behavioral dimension of care (e.g., food delivery) and during one stage of offspring development (e.g., provisioning nestlings). We currently know relatively little about how carers contribute across multiple dimensions of care behavior, or how the distribution of contributions impacts outcomes for carers and offspring. While many studies have explored how carers change the amount they contribute according to the contributions of others (reviewed in Hatchwell, 1999; Harrison et al, 2009), the fine-scale behavioral rules underpinning carer interactions have only recently attracted serious attention (Johnstone et al, 2014)

Objectives

Conclusion