AnalysisThe Non-market Value of Birding Sites and the Marginal Value of Additional Species: Biodiversity in a Random Utility Model of Site Choice by eBird Members
Introduction
From the notion of the “canary in the coal mine”, to the influential book Silent Spring by Carson (1962), birds have long been appreciated as an early indicator of changes in environmental quality. Experts continue to be concerned about the rates of decline for many bird species.1 Human interest in biodiversity among wild birds remains pervasive, with bird-watching (“birding”) continuing to be a popular recreational pursuit. According to the 2011 National Survey of Fishing, Hunting and Wildlife Associated Recreation (NSFHWAR) approximately 46.7 million people in the U.S. reported that they actively engaged in bird watching in the United States in 2011. This is roughly 15 percent of the US population, for people aged 16 and older. Certainly, many other individuals who do not report active participation in bird-watching are likely to derive non-zero utility from “passive” bird sightings even if these sightings are incidental to some other activity in which they are engaged.2
Many birders are “listers” who keep track of all the different species of birds they have seen. Some prestige is attached to having a large number of species on one's life list, and some birders aspire to have a “Big Year”.3 The non-market economic value of species richness to birders, however, remains an open question. Early research considered the value of waterfowl to hunters (e.g. Brown and Hammack (1973)), and the regional economic impacts of wildlife-watching activities have also been documented by the NSFHWAR survey since 1991. For benefit-cost analysis of policies that affect avian biodiversity, however, it would help to know something about the net social benefits associated with bird-watching and how these will be affected by changes in the biodiversity of bird species. Our research responds to this need by utilizing birders' diary data from the Cornell University eBird project, supplemented with data from BirdLife International.
Not much non-market valuation research has been attempted with the data from eBird. The eBird project has been criticized by Lamb (2013) for assigning a universal value of $30 per wild bird, as determined by measures of economic impact as opposed to welfare analysis. We use eBird data to help construct measures of the “expected number of bird species” at different birding destinations, based on the number of species reported in the same month of the previous year. We then use this expected species richness measure as the key biodiversity attribute associated with each birding “hotspot” reported to eBird. Hotspots in eBird are publicly accessible locations that people visit regularly for birding and are suggested to eBird by eBird members. These sites undergo a review by eBird prior to being added to the list. Measuring biodiversity using species richness allows us to estimate the marginal value per trip, to this group of bird watchers, of an additional expected bird species at birding destinations, while controlling for an assortment of other site attributes.
The literature on ecotourism (and more specifically on “avitourism”) is informative about the preferences of bird watchers who take grander-scale trips to visit premium birding destinations outside their local region. Ecotourism has brought to the forefront the value of biodiversity and the importance of conservation e orts because of the economic impact of tourist dollars, i.e. as addressed by Naidoo et al. (2011). Studies in ecotourism and biological conservation point out that ecotourists, in general, tend be interested primarily in distinctive and charismatic species, such as the large mammalian predators of the African Savannah, as described in Di Minin et al. (2013a), Di Minin et al. (2013b), or Grünewald et al. (2016). This literature also explores the issue of how to broaden the interests of ecotourists to include a wider array of species, as in Di Minin et al. (2013b).
In some ecotourism contexts, it is something distinctive about the destination that draws ecotourists. For example, Naidoo and Adamowicz (2005) find that bird species richness and wildlife viewing are significant predictors of which rainforest reserves tourists choose to visit in southern Uganda. For Finland, Siikamäki et al. (2015) find that national parks with the highest biodiversity values attract more visitors than those with lower levels of biodiversity. In other cases, Booth et al. (2011) determine that the rare appearance of some species, such as a “vagrant” bird species, will temporarily increase the number of bird watchers travelling to a particular destination.
Compared to the research to be described in this paper, the closest recent valuation studies of birds employ either the travel cost methodology or stated preference methods. Some recent single-site travel cost models include (1) Edwards et al. (2011), who estimate the economic value of viewing migratory shorebirds, and (2) Gürlük and Rehber (2008) who estimate the economic value of bird watching at a single park. Stated preference studies sometimes focus on the value of a specific type of bird, often an iconic, endangered or threatened species, for example Yao et al. (2014), Myers et al. (2010), Loomis and Ekstrand (1997), Edwards et al. (2011), and Stoll et al. (2006). Other stated preference studies also focus on the value of birds at one particular site, such as Naidoo and Adamowicz (2005), Hvenegaard et al. (1989) or Cooper and Loomis (1991).4
Revealed-preference methods (based on observed travel costs to different birding destinations and formal modeling of preferences) are desirable because they reflect actual birder behavior and permit us to infer measures of consumer surplus. We develop a random-utility recreational site-choice model, using the Cornell eBird hotspot data set for the states of Oregon and Washington in the northwest U.S. We demonstrate the feasibility of using citizen science data to estimate the value of bird biodiversity to these citizen scientists. We derive fitted values for trips to specific types of birding sites based on observed birder choices, differences in expected bird species richness across sites, as well as other (potentially correlated) differences in site attributes. Utility-preserving trade-offs between money and site attributes can then reveal the implied total willingness to pay (TWTP) for birding trips to particular types of sites, as well as marginal willingness to pay (MWTP) for incremental numbers of bird species.
Section snippets
Data
The eBird dataset contains information contributed by bird-watchers who are project members. The early data starting in 2002 were rather sparse, but the number of members has expanded greatly since 2009. Worldwide membership in early 2016 exceeded 307,000. The available information includes the trip entries of individual bird watchers, so that it is possible to connect the trip origin (the member's enrollment-date home address from their member profile) and the geocoded destination for each
Basic Specification With Seasonality and Site Attributes
Within our conditional logit random utility method (RUM) framework, we assume that birder i's utility associated with a bird-watching trip to site j on choice occasion t, namely Ujti, has a systematic component, Vjti, that depends (linearly, for convenience) on income net of the full cost of round-trip travel to that site, (Yi − Cjti). The marginal utility of net income (i.e. other consumption) is given by the coefficient α. Utility also depends on the expected bird species richness measure
Results
We simplify the discussion of our results by featuring only the key coefficient estimates in Table 2. The first three columns of results in Table 2 give selected parameter estimates for a sequence of three increasingly general mixed-logit specifications. Model 1 explains site choices using only travel costs, the expected number of bird species and an interaction term between the expected species and the deviation of median census tract income from the sample average of median census tract
Welfare Calculations: Simulations of TWTP and MWTP
Our sample of eBird members is not necessarily representative of all birders, or even of all birders in the states of Washington and Oregon. Thus it would be inappropriate to emphasize the mean fitted total willingness to pay across the birding trips taken by just these birders, or to attempt to extrapolate these values to the general population. Instead, we wish to illustrate the scale of the implied welfare effects of different statistically significant determinants of utility for these
Caveats and Directions for Future Research
The members of eBird may not be entirely representative of the population of people who enjoy opportunities to see birds. For citizen science data such as that collected by eBird to be most useful for economic analyses such as this, it would be extremely helpful to know more about self-selection into participation in citizen science projects. For example, it might be possible to add a question about the respondent's participation in different citizen science projects to the screening version of
Conclusions
The main contribution of this research is to demonstrate the use of diary data from the eBird citizen science project to estimate a detailed random utility model of destination site-choice for these birders. The richness of the diary data from eBird provides us with an unbalanced panel data set for individual trips taken to a wide variety of destinations over a large spatial extent. This model allows us to infer the trade-o s made by a group of recreational birders based upon their revealed
Acknowledgements
Steve Kelling at the Cornell University Laboratory of Ornithology generously provided us with access to the eBird data. We are grateful for comments from participants at the University of Oregon Microeconomics Brown Bag seminar, the Spring 2014 Oregon Resource and Environmental Economics Workshop at Willamette University, and the 2014 Annual Conference of the Western Economic Association International in Denver, CO. Thanks to Wesley Wilson, Ralph Mastromonaco, Scott Bridgham, Dan Gleason and
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