Why Birds Matter: Avian Ecological Function and Ecosystem Services

Why Birds Matter: Avian Ecological Function and Ecosystem Services


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For over one hundred years, ornithologists and amateur birders have jointly campaigned for the conservation of bird species, documenting not only birds’ beauty and extraordinary diversity, but also their importance to ecosystems worldwide. But while these avian enthusiasts have noted that birds eat fruit, carrion, and pests; spread seed and fertilizer; and pollinate plants, among other services, they have rarely asked what birds are worth in economic terms. In Why Birds Matter, an international collection of ornithologists, botanists, ecologists, conservation biologists, and environmental economists seeks to quantify avian ecosystem services—the myriad benefits that birds provide to humans.

The first book to approach ecosystem services from an ornithological perspective, Why Birds Matter asks what economic value we can ascribe to those services, if any, and how this value should inform conservation. Chapters explore the role of birds in such important ecological dynamics as scavenging, nutrient cycling, food chains, and plant-animal interactions—all seen through the lens of human well-being—to show that quantifying avian ecosystem services is crucial when formulating contemporary conservation strategies. Both elucidating challenges and providing examples of specific ecosystem valuations and guidance for calculation, the contributors propose that in order to advance avian conservation, we need to appeal not only to hearts and minds, but also to wallets.

Product Details

ISBN-13: 9780226382463
Publisher: University of Chicago Press
Publication date: 08/24/2016
Pages: 368
Product dimensions: 6.10(w) x 9.10(h) x 1.00(d)

About the Author

Çağan H. Şekercioğlu is professor in the Department of Biology at the University of Utah, associate of ornithology at the Harvard University Museum of Comparative Zoology, and distinguished visiting fellow at Koç University of Istanbul. He is coauthor, most recently, of Conservation of Tropical Birds and Winged Sentinels: Birds and Climate Change. Daniel G. Wenny is landbird senior biologist at the San Francisco Bay Bird Observatory and visiting research scholar at the Museum of Vertebrate Zoology, University of California, Berkeley. Christopher J. Whelan is visiting research associate professor in the Department of Biological Sciences at the University of Illinois at Chicago and a research affiliate at the Field Museum, Chicago. He is coeditor of Restoration of Endangered Species: Conceptual Issues, Planning and Implementation.

Read an Excerpt

Why Birds Matter

Avian Ecological Function and Ecosystem Services

By Çagan H. Sekercioglu, Daniel G. Wenny, Christopher J. Whelan

The University of Chicago Press

Copyright © 2016 The University of Chicago
All rights reserved.
ISBN: 978-0-226-38246-3


Bird Ecosystem Services

Economic Ornithology for the 21st Century

Christopher J. Whelan, Çagan H. Sekercioglu, and Daniel G. Wenny

The iconic photograph Earthrise, taken by astronaut William Anders as the US space mission Apollo 8 first orbited the moon, captured as never before the isolation of our blue planet in the vast blackness of space. The fragility, interconnectedness, and mutual dependencies of the myriad inhabitants of Spaceship Earth depicted in this stunning photograph propelled the environmental movement around the world.

In this volume, we explore one of the lasting legacies of Earthrise and the environmental movement it helped spark. Ecosystem services are those aspects of the earth that benefit humans (Sekercioglu 2010). The history of ecosystem services has been explored in depth elsewhere (chapter 2; Daily 1997; Gómez-Baggethun et al. 2010). After the term was coined by Ehrlich and Mooney (1983), the number of scientific papers that address the subject increased slowly for a number of years, but soon exploded exponentially (fig. 1.2). Investigation of the ecosystem services provided by a variety of taxa is now well underway (fig. 1.3), though much work lies ahead. Here we provide an update on the state-of-the-art regarding ecosystem services provided by birds.

The Millennium Ecosystem Assessment (MA 2003) brought the concept of ecosystem services to the forefront of policy debate throughout the world (Gómez-Baggethun et al. 2010). The major objectives of the MA were to evaluate the potential consequences of ecosystem change from a broad perspective of human well-being, with an emphasis on ecosystem services. The MA (2003) identified four classes of ecosystem services: "provisioning services such as food, water, timber, and fiber; regulating services that affect climate, floods, disease, wastes, and water quality; cultural services that provide recreational, aesthetic, and spiritual benefits; and supporting services such as soil formation, photosynthesis, and nutrient cycling." We will use these four classes throughout this volume.

Two important offshoots of the MA include the Natural Capital Project (NatCap) and the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES). NatCap, a partnership among the Nature Conservancy, the World Wide Fund (WWF) for Nature, and Stanford University, promotes scientifically rigorous approaches and tools to incorporate the value (natural capital) of ecosystem services into both public and private investment and development decisions. IPBES, founded in April 2012, aims to provide a forum for the scientific community, governments, and other stakeholders, for dialog and exchange of information centered on biodiversity and ecosystem services. IPBES is an independent intergovernmental body open to all member countries of the United Nations. Both NatCap and IPBES represent mechanisms by which the different types of values of nature, including economic value, can be discussed and accounted for in a wide range of policy-formation processes.

Birds and Ecosystem Services

Birds contribute the four types of ecosystem services recognized by the MA. Provisioning services are provided by both domesticated (poultry; Larson 2015) and nondomesticated species. Birds have long been important components of human diets (Moss and Bowers 2007), and many species, particularly waterfowl (Anatidae) and landfowl (Galliformes), are still today (Peres 2001; Peres and Palacios 2007). In developed countries, many birds are hunted for consumption and recreation (chapter 6; Bennett and Whitten 2003; Green and Elmberg 2014). In some developing countries, many species are hunted for subsistence. Bird feathers provide bedding, insulation, and ornamentation (Green and Elmberg 2014). As discussed by DeVault et al. (chapter 8), scavengers contribute regulating services, as efficient carcass consumption by obligate and facultative scavengers helps regulate human disease. Through their place in art, photography, religious custom, and bird-watching, birds contribute cultural services. Bird-watching, or birding, is one of the most popular outdoor recreational activities in the United States and around the world (see below). Numerous bird species contribute supporting services, as their foraging, seed dispersal, and pollination activities help maintain ecosystems that humans depend upon for recreation, natural resources, and solace throughout the world (Sekercioglu 2006a; Wenny et al. 2011; Sodhi, et al. 2011). However, the decline of bird populations worldwide, especially those of more specialized species (Sekercioglu 2011), means that birds' ecosystem services are also declining.

Birds possess a variety of characteristics making them particularly effective providers of many ecosystem services. Most birds fly, so most are highly mobile, with high mass-specific metabolic rates (hence, high metabolic demands). These characteristics allow birds to respond to irruptive or pulsed resources in ways generally not possible for other vertebrates. Their mobility also allows them to track resource abundance, vacating areas in which resources are no longer sufficient and moving to areas where they are. Because many species are migratory, birds link geographic areas separated by great distances over a variety of temporal scales. Different bird species exhibit a wide range of social structures during any given phase of the annual cycle. For example, many species are territorial when breeding, but others breed colonially. Finally, in various bird species, social structure changes dramatically between breeding and nonbreeding phases of the annual cycle. For many such species, breeding communities are composed of individual pairs of relatively low density, owing to intraspecific (and sometimes interspecific) territoriality. In the nonbreeding season, these species may form heterospecific flocks that can attain extremely high densities. Such differences in social structure may produce large differences in avian impact on the environment.

Importance of natural history

Many of the ecosystem services provided by birds arise through their ecological functions. Evaluating the value of these services requires sound knowledge of natural history — especially resource exploitation, habitat requirements, and interactions with other species (Sekercioglu 2006a,b; Whelan et al. 2008; Wenny et al. 2011). Following the MA classification, most bird services are supporting and regulating services, and of these, most result from bird resource exploitation. Most of the regulating and supporting services arise via top-down effects of resource consumption (chapter 3). With more than 10,600 bird species on earth, birds consume a wide variety of resources in terrestrial, aquatic, and aerial environments. In many cases, the consumed resource is a pest of agricultural crops or forests. In other cases, bird resource consumption facilitates pollination (chapter 4), or movement and deposition of seeds, promoting successful plant reproduction in a large number of plant species (chapters 5,6, and 7). When the plants are of economic or cultural significance, these services benefit humans. An extremely important bird regulating service is consumption of animal carcasses (chapter 8). Of particular significance is the global reach of these services, particularly insect control, seed dispersal, and scavenging. Through these services, birds have a large but as yet mostly unquantified impact on ecosystems. Developing methods to quantify bird impact in this functional sense, along with methods to monetize or place value on it, is critical. Clearly, the first step is to thoroughly understand the natural history involved. Key issues include:

How many species perform particular ecological functions?

How variable in space and time are they?

What ecological factors promote them?

Direct and Indirect Ecosystem Services

Some ecosystem services benefit humans directly, as when eider down is used as insulation in jackets, vests, and sleeping bags. Ecosystem services may also benefit humans indirectly, as when seed dispersal of plant species not used directly by humans as commodities nonetheless supports other plant and/or animal species that humans do depend on for utilitarian purposes. Cultural and provisioning services tend to fall into the direct service category, whereas regulating and supporting services tend to fall into the indirect category. As the following chapters describe in detail, the majority of ecosystem services provided by birds are indirect supporting services. Because of this, the ecological roles of birds are not usually included specifically in models assessing ecosystem services (e.g., Kareiva et al. 2011). Yet the examples throughout this book suggest that birds' ecological roles — and, therefore, their ecosystem services — are critical to the health of many ecosystems and to human well-being.

Cultural Services Provided by Birds

Humans and birds have a long history of interaction, dating back thousands of years (Podulka et al. 2004). Examples of this long history include the 16,500-year-old cave paintings in Lascaux, France, which clearly depict birds, and 3,000-year-old murals of ancient Egyptians with domesticated ducks and cranes. These two examples illustrate that while human-bird interaction was important enough for ancient peoples to document, the process of documentation transcends the original use of birds as commodities, becoming something of larger cultural significance. While the domestication of birds for food was no doubt important for the Egyptians, the murals depicting those scenes transform a product-driven ecosystem service with quantifiable economic value into an intangible social and cultural service. Fujita and Kameda (chapter 9) discuss a modern-day equivalent, when a cormorant colony husbanded for guano over 100 years was transformed, owing to the adoption of modern fertilizers, into a symbol and source of sentimental attachment by a community in Japan.

Birds often embody symbolic values and important roles in mythology and religion across many cultures, from ancient times to today (Groark 2010; Mazzariegos 2010). Particular bird species, owing to their majestic appearance, power of flight or sheer beauty (both visual and vocal), were considered symbols of deities, and today are used as mascots and even national symbols (e.g., the bald eagle [Haliaeetus leucocephalus], representing the United States of America). In Guatemala the national currency is called the quetzal, after the national bird, the resplendent quetzal (Pharomachrus mocinno). Birds have variously represented omens of hope, wisdom, and fear.

Birds and Recreation

Recreational services provided by birds can be quantified accurately. Prominent among them is bird-watching, or birding. As of 2008, some 81 million people in the United States enjoy watching birds, and this population is projected to increase to 108 million people by 2030 (White et al. 2014). In 2001 alone, US birders spent $32 million enjoying their hobby, creating $85 million in indirect economic impact and supporting nearly one million jobs (LaRouche 2001; see also Sekercioglu 2002). The rise in popularity of bird-watching, especially in the past 50 years, has spawned field identification guides, an entire genre of books (Dunlap 2011) that has also expanded to cover other taxa. Similarly, the demand for bird-watching trips contributes to the current boom in ecotourism. An offshoot of recreational interest in birds is the rise of citizen science programs that use knowledgeable volunteers to help monitor bird populations on a large geographic scale (e.g., www.ebird.org; Abolafya et al. 2013). Bird-watching is an international industry employing guides in many countries, including developing countries, where it can be a significant source of income (Sekercioglu 2002). Some of these endeavors contribute proceeds to the preservation of land for bird conservation, often of critically endangered birds (Stevens et al. 2013).

More than 37 million people visited the 97 million acres encompassing the National Wildlife Refuge System in the United States in 2006 (Carver and Caudill 2007). There, they engaged in nonconsumptive activities like observing and photographing wildlife, hiking, and environmental education, as well as consumptive activities like fishing and hunting. Eighty-two percent of total expenditures were spent on nonconsumptive activities, 12% were spent on fishing, and the remaining 6% were spent on hunting. Beyond the National Wildlife Refuge system, more than 87 million Americans (38% of the US population 16 years old or over) spent some $120 billion pursuing outdoor recreation of some kind. Of those 87 million Americans engaged in outdoor recreation, about 48 million spent that time birding, a 5% increase over 2001.


The art or sport of falconry, the "sport of kings," dates to 2000 BCE in Mesopotamia, and it remains popular today in many countries. Traditionally, actual falcons (genus Falco) were the bird of choice. Today, species in various other genera (e.g., Accipiter, Buteo, Circus) are often used. Unfortunately, the great value placed on certain species (e.g., the peregrine falcon, Falco peregrinus) has over the years spawned an illicit trade for those species, which can fetch extraordinary prices on the black market (Wyatt 2011). For example, saker falcons (Falco cherrug) are globally endangered as a result of the falconry trade (Dixon et al. 2011).

Cage Birds

Hundreds of millions of people keep cage birds, a practice that is increasingly impacting bird populations worldwide, particularly in Asia (BirdLife International 2013a). Captive-bred birds in accredited zoos can raise awareness, educate the public, and contribute to bird conservation. A few conservationists have even succeeded in involving cage bird enthusiasts in bird conservation programs based on captive breeding, most famously exemplified by the Spix' Macaw (Cyanopsitta spixi; BirdLife International 2013b). However, the cage bird trade overall threatens wild bird populations worldwide (BirdLife International 2013a).

Birds in Art

Birdlife International (2008) reports that Herbert Friedmann (1946) investigated Renaissance religious paintings and found that the European goldfinch (Carduelis carduelis) appears frequently in them. The goldfinch is often held by an infant Jesus, apparently symbolizing a variety of religious themes such as the soul, resurrection, sacrifice, and death. Artists include Leonardo da Vinci (Madonna Litta, 1490 – 91), Raphael (Solly Madonna, 1502, and Madonna of the Goldfinch, 1506), Zurbarán (Madonna and Child with the Infant St. John, 1658) and Tiepolo (Madonna of the Goldfinch, 1760; Birdlife International 2008). Birds are often depicted or have inspired various musical compositions, such as Vivaldi's Flute Concerto in D ("The Goldfinch"), Oliver Messiaen's Réveil des Oiseaux, and Jerry Garcia's "Bird Song." On the other hand, birds are often portrayed inaccurately in movies and on television (Chisholm 2007). Examples include the numerous instances of red-tailed hawk (Buteo jamaicensis) vocalizations used to convey the fierceness of a bald eagle (Haliaeetus leucocephalus) or even of the mostly nonvocal turkey vulture (Cathartes aura).

Birds in Science

Birds have long played a critical role in the sciences (Konishi et al. 1989). From the age of Aristotle, who speculated on the appearance and disappearance over the annual cycle of certain species (now known as migration), birds have stimulated and challenged the human intellect. Study of birds has contributed to the fields of navigation (Griffin 1964; Wiltschko and Wiltschko 2013), aerodynamics (Kantha 2012), ecology (MacArthur 1972), evolutionary ecology (Lack 1947), neurobiology (Nottebohm 1984), and physiology (Karasov 1990), among numerous others. Birds were also the inspiration for the initial large-scale citizen science projects, the Christmas Bird Count and the North American Breeding Bird Survey (Altshuler et al. 2013), and they continue to inspire such projects today (e.g., ebird.org; Greenwood 2007). The data gathered by bird-watching has led to important conservation findings, such as projection of the effects of climate change on bird distributions (Abolafya et al. 2013; Wormworth and (Sekercioglu 2011).


Excerpted from Why Birds Matter by Çagan H. Sekercioglu, Daniel G. Wenny, Christopher J. Whelan. Copyright © 2016 The University of Chicago. Excerpted by permission of The University of Chicago Press.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.

Table of Contents

Foreword by Jeffrey A. Gordon

Chapter 1. Bird Ecosystem Services: Economic Ornithology for the 21st Century
Christopher J. Whelan, Çağan H. Şekercioğlu, and Daniel G. Wenny

Chapter 2. Why Birds Matter Economically: Values, Markets, and Policies
Matthew D. Johnson and Steven C. Hackett

Chapter 3. Trophic Interaction Networks and Ecosystem Services
Christopher J. Whelan, Diana F. Tomback, Dave Kelly, and Matthew D. Johnson

Chapter 4. Pollination by Birds: A Functional Evaluation
Sandra H. Anderson, Dave Kelly, Alastair W. Robertson, and Jenny J. Ladley

Chapter 5. Seed Dispersal by Fruit-Eating Birds
Daniel G. Wenny, Çağan H. Şekercioğlu, Norbert J. Cordeiro, Haldre S. Rogers, and Dave Kelly

Chapter 6. Dispersal of Plants by Waterbirds
Andy J. Green, Merel Soons, Anne-Laure Brochet, and Erik Kleyheeg

Chapter 7. Seed Dispersal by Corvids: Birds That Build Forests
Diana F. Tomback

Chapter 8. Ecosystem Services Provided by Avian Scavengers
Travis L. DeVault, James C. Beasley, Zachary H. Olson, Marcos Moleón, Martina Carrete, Antoni Margalida, and José Antonio Sánchez-Zapata

Chapter 9. Nutrient Dynamics and Nutrient Cycling by Birds
Motoko Fujita and Kayoko O. Kameda

Chapter 10. Avian Ecosystem Engineers: Birds That Excavate Cavities
Chris Floyd and Kathy Martin

Chapter 11. Avian Ecological Functions and Ecosystem Services in the Tropics
Çağan H. Şekercioğlu and Evan R. Buechley

Chapter 12. Why Birds Matter: Bird Ecosystem Services That Promote Biodiversity and Support Human Well-Being
Çağan H. Şekercioğlu, Daniel G. Wenny, Christopher J. Whelan, and Chris Floyd


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