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How Do Migratory Add Value to Wilderness? Calculating the Spatial Subsidies Provided by Protected Areas

BY LAURA LÓPEZ-HOFFMAN, DARIUS SEMMENS, and JAY DIFFENDORFER

Abstract: Species that migrate through protected and wilderness areas and utilize their , deliver ecosystem services to people in faraway locations. The mismatch between the areas that most support a species and those areas where the species provides most benefits to society can lead to underestimation of the true value of protected areas such as wilderness. We present a method to communicate the “off-site” value of wilderness and protected areas in providing habitat to migratory species that, in turn, provide benefits to people in distant locations. Using northern pintail ducks (Anas acuta) as an example, the article provides a method to estimate the amount of subsidy – the value of the ecosystem services provided by a migratory species in one area versus the cost to support the species and its habitat elsewhere.

Introduction Wilderness and protected areas generate benefits well beyond their boundaries – many species that migrate through wilderness areas and utilize their resources, deliver ecosystem services to people in faraway locations (Semmens et al. 2011; López-Hoffman et al. 2010). Migratory species – such as birds, mammals, fish, and insects that regularly migrate between two or more different areas – pro- Laura López-Hoffman Darius Semmens Jay Diffendorfer vide ecosystem services to people, such as controlling crop pests, pollinating , or supporting recreational many other migratory species depend on wilderness areas for , fishing, and bird-watching. For example, the food, shelter, and breeding habitat (see Figure 1). migratory Mexican free-tailed bat (Tadarida brasiliensis This mismatch between the areas that most support a mexicana) helps control cotton crop pests in the south- species and those where the species provides most benefits to western and northern Mexico. Female bats society can lead to underestimation of the true value of pro- migrate annually from central Mexico to the U.S.-Mexico tected areas such as wilderness. People, and most critically borderlands where they feed on corn earworm/cotton boll- decision makers, may not realize that locally used ecosystem worm, providing an estimated $700,000 worth of pest services may be linked to (supported by) distant protected control annually in one region of Texas (Cleveland et al. areas. In the United States, in an era of concern about visita- 2006). Throughout the yearly cycle of migration, bats and tion rates to national parks and wilderness areas (Pergams PEER REVIEWED

14 International Journal of Wilderness APRIL 2013 • Volume 19, Number 1 spatial subsidies one location provides to, or receives, from others. All locations regularly used by a migratory species can both provide and receive benefits via migration sup- port. Locations provide benefits by contributing to the overall viability of migratory species that in turn provide services to elsewhere in their range. Locations receive benefits in the form of services provided locally by migratory populations that are depen- dent on distant areas. Therefore, the net ecosystem service subsidy either provided or received by an area is a balance between the services received Figure 1 – Mexican free-tailed bats near Bracken Cave near San Antonio, Texas. Photo by A. Russell. from a species dependent on other locations and the support the area pro- and Zaradic 2008; Cordell et al. 2008), communicate the value of protected vides to the species. The following it is important to be able to under- areas to people and decision makers in description of how the subsidy can be stand, calculate, and communicate the distant locales. calculated is excerpted from Semmens full value of wilderness (Watson and et al. (2011), which can be referenced Venn 2012), including the “on-site” Calculating the Spatial for additional details. benefits provided within or near pro- Subsidy Provided by a For a single species, the gross tected areas and the “off-site” benefits migration support provided (out) by provided to people far beyond area Consider a wildlife refuge on a migra- location A to all other locations, MAo, boundaries (Loomis and Richardson tory flyway that is widely judged a is simply the value of migratory ser- 2001). The purpose of this article is to “critical” stopover site for birds. vices provided at all other locations present a method to communicate the Scientists trying to ascertain the eco- multiplied by the species’ proportional “off-site” value of wilderness areas in system service “value” of this refuge dependence on location A: providing habitat to migratory species would traditionally consider the that, in turn, provide benefits to people number of visitors, how much the (1) in distant locations. average visitor spends, and any other Where VS is the total value of ser- What is the full ecosystem service goods or services extracted from or vices provided by a species S throughout value of protected areas? How do pro- provided by the refuge. If they were to its range, VSA is the value of services tected areas support the delivery of consider the birds, however, they provided at location A, and DSA is the ecosystem services in distant locations would recognize the refuge plays an proportional dependence of the spe- by providing habitat for migratory important role in supporting bird cies’ population on location A. species? Using northern pintail ducks migration and thus the overall ability Locations can be defined in any (Anas acuta) as an example, we (1) of the species to provide ecosystem manner and number, provided they outline a method to estimate the services in other locations – a service encompass the full migratory range of amount of subsidy – the value of the that was previously unaccounted for in a species. Values for DS must satisfy ecosystem services provided by pintails the valuation of the refuge. This the following two requirements: in one area versus the cost to support “migration support” is a type of sup- 0 ≤ DSL ≤ 1 the species and its habitat elsewhere, porting service (sensu Millennium (2) describe how the approach can be Ecosystem Assessment 2003) provided applied to account for individual wil- by . By understanding the where DSL represents the propor- derness areas, and (3) suggest how of migration support as an eco- tional dependence at any given such an approach could be used to system service, it is possible to quantify location, and L encompasses all m

APRIL 2013 • Volume 19, Number 1 International Journal of Wilderness 15 locations used by a species. The latter tial subsidies for three species: northern requirement assumes migratory spe- pintail ducks, monarch butterflies cies are dependent on the persistence (6) (Danaus plexippus) and Mexican free- of favorable conditions across their tailed bats. entire range; they cannot be more or less than 100% dependent on their (7) Global Importance of environment. Wilderness for Migratory The gross migration support The migratory ranges of each spe- Species received (in) by a location from all cies need not overlap completely. Around the world, many wilderness other locations, MAi, is the product of Equation 6 still satisfies the require- and protected areas support migratory a species’ dependence on all other loca- ment of Equation 4, provided that the species, often by design. For instance, tions and the value of services provided combined spatial extent of all ranges is the Monarch Butterfly locally: considered. Reserve in Mexico supports overwin- Despite the conceptual frame- tering congregations of eastern North (2) work, estimating real values for VS and American monarchs, and the Maasai The migration support values cal- DS presents a substantial challenge. Mara/Serengeti National Parks in Africa culated in Equations 1 and 2 are based Estimates of VS must be location spe- support massive migrations of wilde- on the annual monetary value of ser- cific, yet measured across all locations. beests and other ungulates. In the vices provided by the migratory species This creates considerable hurdles both United States, the U.S. Fish and Wildlife (see Semmens et al. 2011 for a discus- in the required ecological under- Service refuge system and other man- sion of how nonmonetary values could standing of a species and its valuation aged in the Prairie Pothole Region be incorporated into this approach). at each location. Estimates of DS must account for only 2% of the breeding The net difference between out- allow comparisons of different sites in habitat for all waterfowl, yet contribute going and incoming migration support terms of their contribution to overall to 23% of the overall waterfowl pro- is the spatial subsidy for location A population growth or viability. The duction (USFWS 2007), indicating (YA): most difficult aspect of estimating DS that these managed lands play an (3) and VS lies in developing demographic important role in waterfowl demog- Positive values indicate location A and economic data across all sites – raphy. Many other reserve systems is subsidizing other areas. Negative very few studies approach migratory around the world support migratory values indicate location A is being sub- species from a population level, or birds, such as Keoladeo National Park sidized by other areas. When applied systematically address their functional in India, Radipole Lake to all locations, L, throughout a spe- interactions with humans. As a result, in the UK, the nature reserve system in cies’ range, Equation 3 satisfies the data limitations will hamper the appli- Israel (an important geographic loca- requirement that the sum of all subsi- cation of our approach in the short tion for bird migration between Africa, dies is zero, or term and permit analyses for only Europe, and western Asia), and those charismatic, endangered, or eco- numerous World Heritage sites. Within (4) nomically important species that are countries or regions, reserve systems the best studied and monitored. In the also support smaller-scale altitudinal For a given location, the total long term, the approach demands sub- migration, such as the migration of annual value resulting from its use by stantial investment in, and coordination resplendent quetzals and other tropical a migratory species is the sum of the of, new data collection, monitoring, forest birds in Costa Rica, and ungu- spatial subsidy and value of services and database development to system- lates in , United States. provided locally: atically address migratory species. To date, there are no published examples Example of Northern (5) of spatial subsidy calculations. Pintail Ducks Equations 3 and 5 can be rewritten However, a U.S. Geological Survey Northern pintail ducks are a popular to accommodate multiple species by Powell Center for Analysis and species for hunting and wildlife simply summing across all n species of Synthesis working group led by the viewing. Pintails generally overwinter interest. authors is attempting to calculate spa- in the southern United States and

16 International Journal of Wilderness APRIL 2013 • Volume 19, Number 1 Mexico and fly north each spring to breed in the northern United States and (the majority of the pin- tail population occurs in the western part of the continent, despite a broad distribution across North America). Through their migration, pintail ducks create ecological and economic links between distant locations. The poten- tial for a large ecosystem service subsidy exists because the vast majority of the harvested birds (80–90%, Miller and Duncan 1999) are taken in the United States, yet breeding habitats in Canada play a large role in overall pintail pop- ulation dynamics. Indeed, the leading Figure 2 – Northern pintail ducks in Kolkata, West Bengal, India. Photo by J. M. Garg. License held by Creative hypothesis for historic pintail declines . is the intensification of agriculture in the prairie pothole region of western To assess the subsidy provided by subsidy or proportional dependence Canada (Miller and Duncan 1999; an individual protected area, we sug- values among subareas, such as a wild- Podruzny et al. 2002; Miller et al. gest adapting Mattson et al. (2012) to refuge. These types of geographic 2003) (see Figure 2). understand how pintail demographic analyses are becoming commonplace How can we estimate the spatial processes vary across the modeled given the increasing use of species dis- subsidies in ecosystem services (harvest regions. The maps of protected area tribution modeling (Scott et al. 2002) of pintails) between locations where boundaries could be compared to maps and provide a potentially powerful birds are harvested versus places that of how the contributes to a method for overcoming the scale dis- support the pintail population? A prom- species’ demography to estimate the crepancy between the regional ising approach is to combine harvest subsidy provided by particular pro- population models with which pro- value information with a demographic tected areas. For pintails in the Prairie portional dependence is estimated and model of pintails via the method Potholes, this is nearly possible. the more local scale at which subsidy described earlier. Mattson et al. (2012) Podruzny et al. (2002) analyzed data values are needed. developed a demographic model for from 72 transects spanning an area pintails in North America. The model about 600 x 400 miles (1000 x 600 Applications included three breeding populations km) in the Canadian Prairie Potholes. Migratory Species and Spatial (, northern Canada, and the This area represents about 60% of the Subsidies as a Communication Tool Prairie Potholes), and two nonbreeding Prairie Pothole breeding population in In a large and diverse country such as populations (California and the Gulf Mattson et al. (2012). The analysis the United States, communicating the Coast). It modeled both fall and spring determined geographic features that value of a given protected area can be migratory dynamics and was parame- influenced where pintails “settled” or challenging. For example, managers of terized using a wide array of data from chose to breed after their spring migra- parks and wilderness areas west of the nest studies, aerial waterfowl surveys, tion to the prairie. The analysis also Rocky Mountains need to demon- and harvest records. The model can be generated detailed maps of the density strate their value to decision makers used to estimate DS for each of the five of breeding pintails across the region located in the nation’s capital, regions, while harvest data can be used and developed an understanding of , D.C. – more than 2,000 to estimate VS. At this broad geographic how particular vegetation types, agri- miles away – and to stakeholders from scale of North America, the subsidy cultural practices, and pond density around the country. Previous work by calculations can inform policy between affected breeding bird density. Using natural economists has sug- the United States and Canada for pin- these maps it would be straightforward gested that the value of wilderness be tail management. to quantitatively partition regional communicated in terms of on-site and

APRIL 2013 • Volume 19, Number 1 International Journal of Wilderness 17 off-site values (Loomis and Richardson may want to convince the people who for their management and protection. 2001). On-site values are the benefits receive benefits from a migratory spe- The issue of paying a management received or enjoyed locally, such as cies to share in the cost of protecting agency for protecting land that they are , protection of fish and wild- the species’ critical habitats in distant already charged with protecting arose in life habitat, and increased revenues to protected areas. Our method provides the Forest to Faucets Initiative where local communities from visitor expen- a way of identifying who is receiving the Denver, , utility is ditures. The primary metrics of off-site benefits from migration support, paying the U.S. Forest Service for ero- values, to date, are improved down- quantifying the “value” of those bene- sion control and prevention stream and passive-use fits, and connecting them back to activities in agency-owned above existence values to people who many source areas via an equitable subsidy the ’s water-supply reservoirs. Both never visit the area but derive satisfac- calculation. Resource managers could the Forest Service and the city have tion from knowing the area exists and is protected (e.g., Pate and Loomis This approach provides a quantitative means to 1997; Chichilnisky and Heal 1998; Bateman et al. 2006). assess the need for increased conservation for Downstream water-quality im- migratory species and the wilderness and provements are an effective way of demonstrating the regional benefits of protected areas that support them. protected areas – that is, benefits to downstream users – but may not use the calculated subsidy values to argued that the funds are for additional communicate why more distant stake- guide how much people in a receiving actions specifically designed to protect holders should care about protecting location might pay to support conser- and enhance the ecosystem service in wilderness. On the other hand, exis- vation efforts in the protected area(s) question (Denver Water 2011). tence values do capture how distant supplying the subsidy. stakeholders value wilderness but may Payments to support conservation Conclusion be viewed by some as less convincing and efforts and pro- In an era of concern over the numbers (Defries and Pagiola 2005). Our tect ecosystem services have been of visitors to wilderness and protected method of expressing the value of pro- termed “payments for ecosystem ser- areas, park managers and other conser- tected areas to distant people through vices,” or PES. A wide and growing vation advocates in the United States migration support can communicate literature describes PES programs, the are examining new ways to express the the value of protected areas, and it opportunities they present, the chal- value of protected areas and wilderness does so in a way that is quantitative lenges of implementing them, and to decision makers and stakeholders. and easily understandable. As such, it possible negative consequences of Here we present a new approach for provides a valuable addition to the doing so (Engel et al. 2008; The accounting for the value of protected portfolio of tools used by managers Economist 2009; Norgaard 2010). areas through migration support – the and conservation advocates to articu- These important issues must be provision of habitat and resources to late the value of wilderness. addressed when considering PES. Most migratory species that in turn supply of these issues, however, are beyond benefits to people in distant locations. Migratory Species and Spatial the scope of this short communication We believe this approach provides an Subsidies as a Framework for – but we do address one particular effective tool for communicating the Conservation Funding concern that might arise in the United value of protected areas, in particular to As described earlier, protected areas States when considering developing people and decision makers located far can subsidize the delivery of ecosystem PES programs for protected areas that from the areas in question. In addition, services in other locations. In an ideal provide migration support services. this method could be used by decision world of abundant resources for con- In the United States, wilderness makers to communicate the value of a servation, this situation may be tenable. and other protected areas are public migratory species and why protecting However, with the current reality of lands – lands that are owned and set the species’ critical habitats in distant shrinking budgets for conservation, aside by local, state, or federal govern- wilderness and protected areas is impor- park managers and decision makers ments – and receive government funds tant. Through a U.S. Geological Survey

18 International Journal of Wilderness APRIL 2013 • Volume 19, Number 1 Powell Center working group, the 37-71. Washington, DC: Island Press. Pergams, O. R. W., and A. Zaradic. 2008. Denver Water. 2011. From forests to fau- Evidence for a fundamental and perva- authors and colleagues are imple- cets. Retrieved June 14, 2011, from sive shift away from nature-based menting this approach for three North www.denverwater.org/SupplyPlanning/ recreation. Proceedings of the National American migratory species, as we WaterSupply/PartnershipUSFS/. Academy of 105: 2295–2300. The Economist. 2009. Seeing the : A Podruzny, K. M., J. H. Devries, et al. 2002. refine and make the techniques more special report on forests. September Long-term response of northern pin- accessible. This approach provides a 25, 2009. tails to changes in wetlands and Engel, S., S. Pagiola, and S. 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