The Need to Quantify Ecosystem Services Provided By Birds Author(s) :Daniel G. Wenny, Travis L. Devault, Matthew D. Johnson, Dave Kelly, Cagan H. Sekercioglu, Diana F. Tomback, and Christopher J. Whelan Source: The Auk, 128(1):1-14. 2011. Published By: The American Ornithologists' Union URL: http://www.bioone.org/doi/full/10.1525/auk.2011.10248 BioOne (www.bioone.org) is a a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. The Auk An International Journal of Ornithology Vol. No. January The Auk 128(1):1–14, 2011 The American Ornithologists’ Union, 2011. Printed in USA. PERSPECTIVES IN ORNITHOLOGY THE NEED TO QUANTIFY ECOSYSTEM SERVICES PROVIDED BY BIRDS DANIEL G. WENNY,1,8 TRAVIS L. DEVAULT,2 MATTHEW D. JOHNSON,3 DAVE KELLY,4 CAGAN H. SEKERCIOGLU,5,9 DIANA F. TOMBACK,6 AND CHRISTOPHER J. WHELAN7 1Jo Daviess Conservation Foundation, 126 N. Main Street, Elizabeth, Illinois 61028, USA; 2U.S. Department of Agriculture, National Wildlife Research Center, Sandusky, Ohio 44870, USA; 3Department of Wildlife, Humboldt State University, Arcata, California 95521, USA; 4Biological Sciences, University of Canterbury, Christchurch 8140, New Zealand; 5Center for Conservation Biology, Department of Biology, Stanford University, Stanford, California 94305, USA; 6Department of Integrative Biology, University of Colorado Denver, P.O. Box 173364, Denver, Colorado 80217, USA; and 7Illinois Natural History Survey, c/o Department of Biological Sciences, University of Illinois at Chicago, 845 W. Taylor Street, Chicago, Illinois 60607, USA What are birds worth—what is their actual dollar value to highlight recent steps toward quantifying those services, and, fi- human society? To most of us in the ornithological community, nally, suggest directions for future research. Overall, we empha- birds are invaluable. But in these times we need more specific ra- size that global efforts to conserve bird populations and sustain tionales to convince policy makers and business leaders to include avian biodiversity also preserve the diverse ecosystem services bird conservation in land-use and development decisions. Over provided by birds, thus contributing to human well-being. the past two decades, awareness of our dependence on a variety of ecosystem services (natural ecological processes that benefit DEFINITIONS AND BACKGROUND human society) and of their importance and prevalence has pro- gressed toward the goal of making conservation a mainstream Ecosystem services are divided into four categories (Millenium value (Ehrlich and Kennedy , Perrings et al. , Rands et al. Ecosystem Assessment ). Provisioning services refer to natu- , Sodhi and Ehrlich ). Building strategies for the protec- ral products that are directly used by humans for food, clothing, tion of ecosystem services into conservation and land-use plan- medicines, tools, or other uses. Cultural services provide recre- ning is essentially the promotion of human survival, although ational opportunities, inspiration for art and music, and spiri- many policy makers misinterpret conservation efforts as luxury. tual value. Regulating services include pest control and carcass Several previous reviews have identified ecosystem services that removal. Supporting services, such as pollination, seed dispersal, benefit human society (Costanza et al. , Daily , Pimentel water purification, and nutrient cycling, provide processes essen- et al. , Sekercioglu ). The challenge, however, is to calcu- tial for ecological communities and agricultural ecosystems. late the value of ecosystem services in meaningful and relevant The Millennium Ecosystem Assessment’s description of eco- ways that can be used to justify the protection of ecosystem ser- system services (Millenium Ecosystem Assessment ) is widely vices in land-use recommendations and policy decisions (Daily et cited, but considerable debate continues on what constitutes an eco- al. , ). As the case studies below illustrate, recent work system service and how each should be quantified (Boyd , Boyd on the ecosystem services provided by birds has made good prog- and Banzhaf , Matero and Saastamoinen , Nijkamp et al. ress toward this goal, but much remains to be done. Our objec- , Bartelmus , Farley and Costanza , Kontogianni et al. tives here are to describe the ecosystem services provided by birds, , Norgaard , Wainger et al. ). The main issues include 8Present address: Loras College, 1450 Alta Vista, Dubuque, Iowa 52004, USA. E-mail: [email protected] 9Present address: Department of Biology, University of Utah, 257 South 1400 East, Room 201, Salt Lake City, Utah 84112, USA. The Auk, Vol. , Number , pages . ISSN -, electronic ISSN -. by The American Ornithologists’ Union. All rights reserved. Please direct all requests for permission to photocopy or reproduce article content through the University of California Press’s Rights and Permissions website, http://www.ucpressjournals. com/reprintInfo.asp. DOI: ./auk.. — 1 — 2 — WENNY ET AL. — AUK,VOL. 128 how to value nonmarket services, how to avoid double counting a although many raptors (both hawks and owls) consume rodents, process and its end product, and how to incorporate ecosystem val- we know of no study that has examined this predator–prey inter- uation into policy and land-use decisions. We do not advocate any action from the perspective of economic value or trophic cascades. particular method of valuation here, but we argue that a consistent A few studies have directly assessed birds of prey as agricultural methodology for calculating units of ecosystem services is needed rodent-control agents, and the results are somewhat ambiguous. (as with any system of weights and measures; Boyd ). Wood and Fee () reviewed measures to control rats in Malay- sian agroecosystems, including deployment of nest boxes to raise OVERVIEW OF ECOSYSTEM SERVICES PROVIDED BY BIRDS populations of Barn Owls (Tyto alba). They concluded that the evi- dence was inconsistent and that the effect of owls warrants further Birds are the best-known class of vertebrate animals, occur world- investigation. Kay et al. () reported that perches placed around wide in nearly all habitats, and provide many services (Sekercio- soybean fields in Australia increased the number of diurnal raptors glu a, b; Whelan et al. ). Thus, they are an ideal group to around and over the fields, which in turn decreased House Mouse examine for ecosystem service valuation. Yet, surprisingly, little (Mus musculus) population growth rate and maximum population ornithological research has been done in an ecosystem-services density in the fields. Perches placed m apart were more effective context. Much ecosystem-services work has been focused on wa- than those placed m apart. Other studies demonstrated that tersheds and insect pollination, perhaps because market value can providing artificial perches attracts various birds of prey, including readily be assigned to both fresh drinking water and agricultural American Kestrels (Falco sparverius), which also suggests that this crops that require pollination (Kremen et al. , Brenner et al. method may enhance or concentrate foraging in potentially ben- ). Similarly, economic aspects of some cultural and provision- eficial ways (Wolff et al. , Sheffield et al. ). Clearly, more ing services such as bird watching and hunting have been quan- research is needed on the potential for birds of prey to drive trophic tified (Sekercioglu , LaRouche , Leonard , Carver cascades in natural and agricultural ecosystems. ). Other historical and cultural aspects of birds have been re- The role of granivorous birds in control of agricultural weeds viewed and quantified in a general way (Diamond and Filion , is essentially unknown, but one example is suggestive. In New Podulka et al. , Mynott ). Most of the important ecologi- Zealand, a granivorous bird introduced for aesthetic reasons, the cal roles that birds fill, however, involve supporting and regulating European Goldfinch (Carduelis carduelis), destroyed × more services, such as insect pest control and seed dispersal, and these seeds of the aggressive pasture weed Carduus nutans than a weevil types of services are the most difficult to quantify (Farber et al. (Curculionidae: Rhinocyllus conicus) that was introduced to pro- ; Sekercioglu a, b; Whelan et al. , ). As we de- vide biological control of C. nutans (Kelly and McCallum ). In scribe below, many of the most important ecosystem services that fact, the % of seed destroyed by goldfinches at that site compares birds provide result from their foraging behavior. Through their favorably to the highest well-documented seed losses attributed to foraging, birds act as mobile links that transfer energy both