Tracking Animal Migration with Stable Isotopes

Keith A. Hobson, Leonard I. Wassenaar

• Publisher: Academic Press
• Year: 2018
• ISBN:
  9780128147245
• Edition: 2
• Topic: Sciences biologiques
• Subtopic: Conservation et Protection de l'Envronnement

Tracking Animal Migration with Stable Isotopes, Second Edition, provides a complete introduction to new and powerful isotopic tools and applications that track animal migration, reviewing where isotope tracers fit in the modern toolbox of tracking methods. The book provides background information on a broad range of migration scenarios in terrestrial and aquatic systems and summarizes the most cutting-edge developments in the field that are revolutionizing the way migrant individuals and populations are assigned to their true origins. It allows undergraduates, graduate students and non-specialist scientists to adopt and apply isotopes to migration research, and also serves as a useful reference for scientists.

The new edition thoroughly updates the information available to the reader on current applications of this technique and provides new tools for the isotopic assignment of individuals to origins, including geostatistical multi-isotope approaches and the ways in which researchers can combine isotopes with routine data in a Bayesian framework to provide best estimates of animal origins. Four new chapters include contributions on applications to the movements of terrestrial mammals, with particular emphasis on how aspects of animal physiology can influence stable isotope values.

• Includes an animal physiology component that is an in-depth overview of the cautions and caveats related to this technique
• Covers marine and aquatic isoscapes and methods to track marine organisms for researchers trying to apply isotopic tracking to animals in these environments
• Features state-of-the-art statistical treatments for assignment and combining diverse datasets

Chapter 1

Animal Migration

A Context for Using New Techniques and Approaches

Keith A. Hobson¹, D. Ryan Norris², Kevin J. Kardynal¹ and Elizabeth Yohannes³, ¹Environment and Climate Change Canada, Saskatoon, SK, Canada, ²University of Guelph, Guelph, ON, Canada, ³University of Konstanz, Konstanz, Germany

Abstract

This chapter attempts to delineate the evolutionary trajectory of animal migration and the technological developments to chart the same. A detailed overview of migratory movements in diverse species is made in order to highlight the various factors involved in defining the term “migration,” following which, the authors turn to migratory populations as a whole, to discuss the concept of migratory connectivity and its links with conservation and effective species management, with particular regard to different breeding practices. The scientific tools employed to track and study the movements of migratory creatures are also outlined, paying close attention to the benefits and pitfalls of using (1) extrinsic markers such as transmitters, radars and satellites and (2) intrinsic markers such as contaminants, trace elements, stable isotopes, and the like. Finally, briefly mentioned are the different technological breakthroughs in the last decade that have helped advance the understanding of animal migration as well as develop suitable conservation approaches.

Keywords

Migration; migratory connectivity; breeding; conservation; extrinsic markers; intrinsic markers

1.1 Introduction

The spatiotemporal movement of organisms determines their interaction with their environments and, therefore, comprises a fundamental aspect of their ecology and evolutionary life history. The degree to which organisms move also characterizes the range of resources they encounter, the array of hazards they experience from predators to hurricanes, and the number of organisms with which they may interact. For animals, movement is very much a question of geospatial scale. While some species may wander nomadically over a landscape of a few square meters for their entire lives, others travel across thousands of kilometers in regular movements that constitute some of the most spectacular natural phenomena on the planet. These migrations are the movements that have captured the interest of researchers, citizen scientists, and laypersons alike and leave us with a true sense of wonderment. Some key proximate questions related to animal migratory movement include: How do these individuals know where they are going? How do they cope with the tremendous physical demands of travel? How do they adjust to unfamiliar or changing environments along the way to their destinations? What are the costs and benefits of migration? How do migratory patterns influence long-term population dynamics? Ultimately, the evolution of migratory movements remains among the most fascinating and challenging to understand.

Finding answers to these fundamental questions has proven to be an immense scientific challenge. A large part of this challenge is related to the limited tools available to researchers to infer or determine large- and small-scale animal movements. This volume explores recent developments in stable isotope techniques which have contributed tremendously to the field of understanding animal movement, dispersal and long-distance migration in terrestrial and marine ecosystems. As we will demonstrate, stable isotope tools are not only a critical component of the larger toolbox but can typically augment other sources and forms of information.

The term migration often evokes images of spectacular seasonal movements of animals, especially birds, over vast distances but involves many taxa (Fig. 1.1). The Arctic Tern (Sterna paradisaea) migrates from breeding grounds in the Arctic to wintering grounds in the Antarctic, an annual round trip of a staggering 40,000 km (Egevang et al., 2010), equivalent to 2 years of day-to-day driving by the average North American motorist. Salmon return by the millions to natal streams at the end of their lives after spending years moving thousands of kilometers in the open ocean (Quinn, 2005). In the first year of their lives, eastern populations of Monarch Butterflies (Danaus plexippus) in North America travel to overwintering roosts in the Transvolcanic Mountain range of central Mexico, a trip that can be over 4000 km for an insect that weighs only 0.5 grams (Flockhart et al., 2013). For those of us living in temperate (and in subtropical) environments, the annual spring and autumn movements of billions of migratory birds, from warblers to waterfowl, likely provide the most familiar examples of migration (Dingle, 2014; Greenberg & Marra, 2005).

Figure 1.1 Examples of migration patterns in different taxa in North America: (A) the Porcupine caribou herd (Rangifer tarandus), (B) songbirds (American Redstart Setophaga ruticilla), (C) insects (Monarch Butterfly Danaus plexippus), and (D) fish (Pacific salmon). Migratory pathways depicted by arrows are only generalizations.

Indeed these movements are spectacular, yet much confusion still exists as to what exactly we mean by migration. Clearly, migration can include both to-and-fro and one-way movements. A to-and-fro or round-trip migration can be characterized by animals either returning on the same path or by individuals following a loop migration pattern. Various other patterns of long- and short-distance movement have been described between origin and destination, especially for birds (Berthold, 1999). For example, leap-frog migration involves individuals at the northern limits of their breeding range traveling the farthest south (in northern hemispheric animals) to most distant wintering grounds, whereas those from more southern breeding regions migrate the least distance to more northern wintering grounds (e.g., Bell, 1997; Kelly, Atudorei, Sharp, & Finch, 2002; Ramos et al., 2015). Longitudinal migration involves all individuals migrating the same approximate distance in a chain pattern or in parallel (Norris et al., 2006; Salomonsen, 1955). Animal migration can be obligate whereby all members of a population move or facultative whereby resource availability may act to determine if migration occurs. Partial migration refers to a situation when only part of the population migrates (Boyle, Norris, & Guglielmo, 2010; Chapman, Brönmark, Nilsson, & Hansson, 2011; Jahn, Levey, Hostetler, & Mamani, 2010). Differential migration describes those situations when migration patterns differ between sexes, age groups, or morphs within a population (Åkesson, 2016; Ketterson & Nolan, 1976; Woodworth et al., 2016).

Some insect species move from the location they were produced to another location where they reproduce the next generation and die. That generation may then move on, repeating the process. For Monarch butterflies, this occurs in a series of one-way steps involving multiple generations before a final cohort returns to their starting point, the discrete overwinter roosts in the mountains of central Mexico (Flockhart et al., 2013). Many salmon species also undertake spectacular migrations from the sea to freshwater rivers where they spawn and die. Although this is often considered one-way movement, it may be more accurately thought of as a “fatal round-trip migration” because offspring first have to migrate downriver where they spend several years at sea and then return to freshwater to spawn and then die (Quinn, 2005).

Altitudinal migration is a short-distance movement between lower and higher elevation habitat. It is commonly thought to happen in response to resource availability (Levey & Stiles, 1992) and weather or climate conditions (Boyle et al., 2010). These movements are more common in the tropics where frugivory or nectarivory is well developed and in more temperate areas of high relief (Boyle, 2017). Migration within the tropics over large distances, known as intratropical migration, occurs in many tropical-breeding bird species and has more recently been observed in several temperate-breeding long-distance migrants (Heckscher, Halley, & Stampul, 2015; Levey & Stiles, 1992; Morton, ...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• List of Contributors
• Preface
• Preface to the First Edition
• Acknowledgments
• Chapter 1. Animal Migration: A Context for Using New Techniques and Approaches
• Chapter 2. Introduction to Conducting Stable Isotope Measurements for Animal Migration Studies
• Chapter 3. Isoscapes for Terrestrial Migration Research
• Chapter 4. Application of Isotopic Methods to Tracking Animal Movements
• Chapter 5. Tracking of Movements of Terrestrial Mammals Using Stable Isotopes
• Chapter 6. Isotopic Tracking of Marine Animal Movement
• Chapter 7. Amino Acid Isotope Analysis: A New Frontier in Studies of Animal Migration and Foraging Ecology
• Chapter 8. Design and Analysis for Isotope-Based Studies of Migratory Animals
• Chapter 9. Isoscape Computation and Inference of Spatial Origins With Mixed Models Using the R package IsoriX
• Chapter 10. Outlook for Using Stable Isotopes in Animal Migration Studies
• Index