Things We Like: Human Preferences among Similar Organisms and Implications for Conservation

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1 DOI /s ORIGINAL RESEARCH Things We Like: Human Preferences among Similar Organisms and Implications for Conservation David L. Stokes # Springer Science+Business Media, Inc Abstract Human preferences will increasingly determine many species prospects for survival. However, aside from a small number of survey-based studies of preference among disparate taxa, human species preferences have received little attention. I determined human aesthetic preferences among a relatively homogenous group, the penguins, from representation in all recently published, comprehensive, popular books of photographs of penguins (n=4 books; 304 photographs). Representation of visually distinguishable types of penguins, measured by total photograph area, was highly skewed and rankings were highly concordant across books, suggesting large and commonly held differences in aesthetic appeal. Multiple regression analysis indicated that amount of warm color was the only significant determinant of representation, and warm color was highly correlated (r 2 =0.96) with mean representation of the penguin types. Body size and neotenic form, traits found to influence human preferences among other animals, were not significant, suggesting that the bases of human species preferences differ by species type. The results of this study indicate that human aesthetic preferences discriminate finely among species and may be based on minor features. Conservationists must be vigilant to the potential for aesthetic responses to influence conservation efforts. Key words Human biodiversity preferences. aesthetics of biodiversity. biodiversity conservation. penguins. color D. L. Stokes (*) Department of Interdisciplinary Arts and Sciences, University of Washington, Bothell, Box , Bothell WA 98011, USA dstokes@u.washington.edu Introduction Much of the world s biodiversity will survive only if humans choose to protect it. Given that people are likely to protect what is important to them, human preferences will be important determinants of many species prospects for survival just as important as more traditional biological concerns such as minimum population sizes and habitat requirements. Despite this, conservationists have devoted comparatively little attention to human biodiversity preferences (for examples see Czech et al., 1998; Kellert, 1996; Montgomery, 2002), and the nature and significance to conservation of biodiversity preferences remain poorly understood (Montgomery, 2002). How might human preferences assist or hamper biodiversity conservation? Can we predict which elements of biodiversity will appeal to people? Is preference influenced by level of imperilment? In our effort to conserve biodiversity, we must better understand the biodiversity preferences of humans, who will decide what to conserve. It has long been known that humans find some animals more appealing than others (Morris, 1967). Pandas, lions, and other charismatic megafauna are considered pleasing (Kellert, 1996; Morris and Morris, 1966), while snakes, spiders, and most other invertebrates are not (Kellert, 1993a; Morris and Morris, 1965). A variety of psychological and evolutionary explanations for these preferences have been offered (reviews in Kellert, 1993b, 1996; Shepard, 1978; Ulrich, 1993). Preference differences among highly distinct taxa are difficult to interpret, both in their proximate cues (what is it about a spider that makes it less appealing than a panda?) and ultimate causes (how do the human fitness consequences of exposure to snakes compare with exposure to lions?). Human preferences among organisms that differ in only a few respects may be more revealing;

2 however, these have not been investigated. Whether such preferences exist, and if so, whether they are strong and general across individuals, remains poorly known. Among many diverse qualities thought to influence the appeal of animals to humans, including economic value, phylogenetic relatedness, and threat to humans, one of the most important appears to be physical appearance or aesthetic quality (Kellert, 1996; Kellert and Berry, 1980). The physical traits of animals that have been most consistently shown to be preferred by humans are large size (Coursey, 1998; Kellert and Berry, 1980; Ward et al., 1998) and neotenic (juvenile) features (Gould, 1980; Hirschman, 1994; Lawrence, 1989; Lorenz, 1943 in Lorenz, 1971). Other physical traits that may influence preference for animals include similarity to humans, shape, type of locomotion, posture, surface texture, and color (Burghardt and Herzog, 1980; Kellert, 1996; Morris,1967). I investigated the aesthetic appeal of similar organisms by determining human preferences among the penguins, a relatively homogenous group consisting of 17 species of predominantly black-and-white flightless birds (Williams, 1995). Penguins are regarded as highly appealing to humans (Davis and Renner, 2003), but while the different species are anatomically, ecologically, and behaviorally similar, they differ sufficiently in size, head and bill proportions, and small highlights of bright color (on bill, eye, crest, face, and neck), that many species can be easily distinguished by the casual viewer, and therefore they may differ in their level of appeal. This study addressed the following questions: Among this generally appealing and uniform group, do humans prefer some types over others? If so, are these preferences general, i.e., are they consistent across humans? What are the traits upon which human preferences are based? And finally, given that human preference may influence conservation effort (Coursey, 1998; Czech et al., 1998), are human preferences affected by degree of imperilment? I determined human preferences by measuring representation of recognizably different types of penguins, morphospecies, in large-format, comprehensive books of photographs of penguins aimed at a popular audience. In using photographic representation as the measure of preference, I assumed that the selection of photographs in the books reflected at least one person s aesthetic preference: the author s, the publisher s, or the author s or publisher s assessment of the public s preferences. Unlike most previous work on human preferences for animals, which is based on questionnaire responses (e.g., Coursey, 1998; Czech et al., 1998; Kellert, 1993a; Kellert and Berry, 1980; Montgomery, 2002), this approach is not subject to possible self-reporting errors (Bishop and Heberlein, 1979; Diamond and Hausman, 1994; Schuman and Johnson, 1976). Furthermore, as books are economic ventures, representation is likely to reflect considered decisions rather than weak preferences. Penguins are an appropriate group for this study because they comprise few enough species that books of photographs can include most or all species. In addition, aside from differences in appearance, all penguins are similar with respect to many other possible determinants of human preference. For example, all types are located far from most people and are of little economic or cultural significance. Thus, measures of preference based on photographic images may be expected to isolate aesthetic appeal from other possible influences. Although penguins occur, for the most part, in remote regions of the world, they are not immune to human threats (Boersma and Stokes, 1995; Davis and Renner, 2003). Twelve species are considered to be at some level of risk by the World Conservation Union (ICUN), including one, the Yellow-eyed (Megadyptes antipodes), classified as endangered (IUCN, 2004). In this respect, penguins are similar to many other organisms, a high proportion of which are threatened by human activities (Wilson, 2002). Improved understanding of human preferences among this popular group may provide insights useful for conservation of the many other species at risk as well. Methods Sample Selection I analyzed photographic representation of penguin types in all available books that met a priori selection standards designed to isolate aesthetic appeal of penguins from other bases of preference and other influences on representation. I restricted the sample to large format books of photographs aimed at the popular adult audience. Books that consisted primarily of text, were written by scientists, or addressed a scientific audience, were excluded both to avoid confounding factual or narrative appeal with aesthetic preference, and to ensure that the sample did not reflect the preferences of a subgroup (scientists) likely to be concerned with matters other than aesthetics. Books designed for children were excluded to avoid confounding effects of changing preferences with age (Kellert, 1996; Morris, 1967). With their large size, colonial habit, and limited mobility on land, penguins of all species may be among the most easily photographed types of wildlife, and therefore ease of photographing was unlikely to influence representation of species in books. However, because representation could be biased by limitations of access to remote sites where some species occur, I included only books that were comprehensive (i.e., those that included most species of penguins and did not focus on a particular geographic region) and

3 published in the last 10 years, when travel to colonies of all species was more feasible than previously. Four books, each produced by a different author and publisher within a five year period, met these criteria: The World of the Penguin (Chester, 1996; republished as Chester, 2001), Penguins of the World (Lynch, 1997), Penguin (Lanting, 1999), and Penguin Planet (Schafer, 2000). In all cases, the authors took all or nearly all of the photographs in the books. Variables For each photograph in each book, my students and I recorded the penguin species and age class (chick, juvenile, adult) depicted, the proportion of the page occupied by the image of the penguin(s), the activity and appearance of the penguin(s), and whether humans or human-related objects (e.g., ships) were visible. We also recorded the primary subject of each photograph: penguin(s) or their surroundings (landscape). A total of 402 photographs of penguins were evaluated. Because I was interested in preferences among nonexperts, I classified the 17 penguins species into eight morphospecies that could be easily distinguished by a nonscientist viewing the photographs. These were: Apte (King Aptenodytes patagonicus and Emperor A. forsteri), Adel (Adelie Pygoscelis adeliae), Chin (Chinstrap P. antarctica), Gent (Gentoo, P. papua), Cres (the six crested species, Eudyptes spp.), Sphe (the four Spheniscus species), Yell (Yellow-eyed), and Litt (Little Eudyptula minor) (Table I). I determined the physical characteristics of adult penguins of the different morphospecies (Table I) from the species accounts and color plates (by John Davies) in Williams (1995). Morphological characteristics recorded were body length, and three indices of neoteny: head length to body length ratio (neoteny1), beak length to head length ratio (neoteny 2), and relative apparent eye size. Neoteny1 and neoteny2 were determined by measuring the Davies drawings of the species with dial calipers to the nearest 0.1 mm. Relative eye size (small, medium, large) was determined from visual inspection of the plates. Large head size relative to body size, short beak relative to head size, and large eyes are all considered neotenic features (Lorenz, 1971). I also quantified the amount of warm color on the head and upper body, the area of the penguin most often included in the photographs. Using Photoshop 7.0 (Adobe Systems, 2002), I digitized the Davies plates, and for each morphospecies calculated the percent of the total pixels composing the image from flipper to top of head (x=11740 pixels, sd=1673, n=8) that were bright yellow or red (Table I). I assigned each morphospecies a conservation status based on the most recent IUCN (2004) assessments. For Table I Characteristics of Penguin Morphospecies Morphospecies Species Scientific name Length (cm) Neoteny1 a Neoteny2 b Eye size c Color d (%) IUCN status e Apte Emperor Aptenodytes forsteri M LC King A. patagonicus Adel Adelie Pygoscelis adeliae L 0.00 LC Chin Chinstrap P. Antarctica M 0.00 LC Gent Gentoo P. papua L 2.06 NT Cres Rockhopper Eudyptes chrysocome M 4.66 V Macaroni E. chrysolophus Fiordland E. pachyrhynchus Snares Island E. robustus Royal E. schlegeli Erect-crested E. sclateri Sphe African Spheniscus demersus M 0.04 V Humboldt S. humboldti Magellanic S. magellanicus Galapagos S. mendiculus Yell Yellow-eyed Megadyptes M 0.03 E antipodes Litt Little Eudyptula minor S 0.00 LC a Neoteny1 = relative head size (head length/body length); higher values more neotenic b Neoteny2 = relative beak length (bill length/head length); lower values more neotenic c Eye size = relative apparent eye size: L = large, M = medium, S = Small d Color = % of upper body and head colored bright red or yellow (see Methods) e IUCN (2004) status: E = endangered, V = vulnerable, NT = near-threatened, LC = least concern Values for each morphospecies are averages of values for component species. Length from Williams (1995). Color, neoteny1 & 2, and eye size calculated from measurements of penguin species plates (see Methods) in Williams (1995)

4 (1 6), and, as the books were comprehensive, this might affect morphospecies representation. Because the public is unlikely to be aware of the rarity or conservation status of different kinds of penguins, I did not include conservation status in the regression, but performed a separate test (oneway ANOVA) of the relationship between conservation status and representation. Percentage variables (% photo area and % warm color) were transformed using the arcsine transformation to better approximate the normal distribution (Zar, 1996). To test for agreement among the four books in representation of the eight morphospecies, I used Kendall s coefficient of concordance (Zar, 1996) calculated from the ranks of morphospecies representation in each book. Fig. 1 Percent of photographs featuring the eight penguin morphospecies in each of four books. In all photographs (n=304), morphospecies was discernible and plumage was typical of adults of the morphospecies. morphospecies consisting of more than one species, morphological, color, and conservation status values are averages of the values for all component species. Analysis For each book, I calculated the number of photographs of each morphospecies and the percent total photograph area allocated to images of each morphospecies. To avoid confounding species preference with landscape preference, I excluded from the analysis 11 photographs in which the landscape was the primary subject. I also excluded 45 photographs that did not permit identification of morphospecies because the penguins were too distant, incompletely shown (e.g., feathers or feet only), or uncharacteristic in appearance (e.g., albino, covered with mud or oil). Photographs in which the penguins depicted were dead or did not have adult plumage (i.e., chicks or juveniles) were also excluded (n=31). Eleven photographs included humans or objects associated with humans (e.g., ships), and I excluded these as well to avoid possible effects of association with humans. A total of 304 photographs featuring identifiable penguin morphospecies remained for analysis. These were distributed among the four books as follows: Chester: 40; Lanting, 71; Lynch, 110; Schaefer, 83. To identify factors associated with preference, I used multiple regression, with % total photograph area devoted to the morphospecies as the dependent variable and independent variables body length, two measures of neoteny, eye size, % warm color, and book as a categorical variable. I also included number of component species because morphospecies varied widely in number of species Results Numbers of photographs were distributed highly unequally across morphospecies (Fig. 1). In all books, Apte penguins were the subject of the greatest proportion of pictures x= 37.5%, SD= 13.2). Cres (x=21.3%, SD= 5.7) and Gent (x= 13.3%, SD=2.2) were also well represented. Adel, Yell, and Litt were the subject of the smallest proportion of photographs (x=6.3%, SD=4.2; x=2.3%, SD=1.3; and x=1.8%, SD=1.1, respectively). Proportion of photograph area occupied by morphospecies followed a similar pattern (Fig. 2), but with even greater representation of Apte (x=48.0%, SD=10.6). Thus, not only was Apte the subject of more photographs, but images of this type occupied more of the page on average than those of other types. By this measure, Adel, Yell, and Fig. 2 Percent of total photograph area occupied by images of the eight penguin morphospecies in four books. In all photographs (n= 304), morphospecies was discernible and plumage was typical of adults of the morphospecies.

5 Fig. 3 Ranks of representation, as indicated by proportion of page area occupied by eight penguin morphospecies, in each of four books. 1=most represented. Ranks were highly concordant (Kendall s test for concordance: W=0.911, χ 2 =25.51, df=7, p<0.001). Mean rank in the four books shown above each morphospecies name. Litt again had the lowest representation (x=3.5%, SD=2.1; x=2%, SD=1.4; and x=1.8%, SD=1.9) respectively. The four books were highly concordant in representation of the different morphospecies (Fig. 3). In all books, Apte ranked highest. Cres ranked second highest in three of the books, and third in the fourth. Gent ranked second through fourth and Sphe ranked third through fifth. None of the remaining types, Adel, Chin, Yell, and Litt, ranked above fourth in any of the books. Yell and Litt ranked next-to-last and last respectively in all except one book, where Yell ranked last and Litt ranked third to last. The selection of photographs on the dust jackets of the books was consistent with the representation pattern in the books. All four books featured Apte penguins on the front jacket, and all except one (Lynch) included only that type. Multiple regression analysis, with percent of photograph area occupied by each morphospecies as the response variable, and length, three indices of neoteny (neoteny1, neoteny2, and eye size), number of species in group, and book as independent variables indicated that only percent warm color (effect test: F=8.51, p<0.01) was sig nificantly related to photographic representation (r 2 =0.86, F 8,23 = 17.14, p<0.0001, standard least squares model). The absence of a significant effect of book is consistent with the concordance analysis indicating similar representation of morphospecies in the four books. The single trait that was significantly associated with representation in the multiple regression analysis, percent warm color, was highly correlated (r 2 =0.96) with mean representation of the eight morphospecies in the four books (Fig. 4). The three morphospecies with substantial amounts of warm color, Apte (yellow and orange on side of face and neck), Cres (yellow eyebrows and red bill and eyes), and Gent (red bill), were the most highly represented, and were represented according to their amount of warm color. The other species had no warm color (Adel, Chin, and Litt) or very little (<0.1%; Sphe and Yell) and low representation. While size, as indicated by body length, was not significantly associated with representation in the multiple regression analysis, it was significantly correlated with mean representation in all books (Fig. 5). The largest morphospecies (Apte) was the most represented, and the smallest species (Litt) was among the least represented. However, the second smallest morphospecies (Cres) was the second most represented. Fig. 4 Mean photographic representation of morphospecies in four books by % of warm color (red and yellow) on upper body. r 2 =0.96, F 1,6 =136.6, p< % values are arcsine transformed. Fig. 5 Mean photographic representation of morphospecies in four books by body length. r 2 =0.60, F 1,6 =9.06, p= Body length from Williams (1995).

6 None of the indicators of neoteny were associated with representation in the multiple regression analysis. The two indices of neoteny based on body proportions (neoteny1 and neoteny2) were weakly correlated with mean representation in all books, but in directions opposite to expectation (Fig. 6a, b), with greater representation of morphospecies that were less neotenic (i.e., small heads relative to body size and long bill relative to head size). The most represented group, Apte, was the least neotenic, as measured by these indices. Similarly, large eye size was not associated with greater representation. Adel penguins have the largest apparent eye because of a prominent eye ring, but were one of the least represented types. In many photographs of the most represented type, Apte, the eyes were not visible because they are dark and surrounded by dark feathers. The low representation of Adel also Fig. 7 Mean photographic representation of morphospecies grouped by IUCN conservation status (LT=least threatened, NT=Near threatened, VU=vulnerable, EN=endangered). One-way ANOVA, F 3,4 = 0.207, p= Values in parentheses indicate number of morphospecies in each group. Bars indicate standard error. suggests that familiarity was not important, as this is probably the penguin most familiar to the public. There was no significant relationship between degree of imperilment and representation in the books (Fig. 7). The species rated by IUCN as most imperiled, the Yellow-eyed penguin, was among the least represented. The species constituting the most represented morphospecies, King and Emperor penguins, are not regarded as imperiled (IUCN, 2004). Inasmuch as degree of imperilment is negatively correlated with population size, morphospecies representation might be expected to be influenced by availability of penguins to photograph. However, the lack of a significant relationship between representation and imperilment and the fact that some of the most numerous species (e.g., Adel and Chin) were among the least represented indicates that representation was not determined by penguin numbers. Discussion Fig. 6 a. Mean photographic representation of morphospecies by relative head size (head length/body length). Larger relative head size is more neotenic. r 2 =0.58, F 1,6 =8.41, p= b. Mean photographic representation of morphospecies by relative bill length (bill length/ head length). Smaller relative bill length is more neotenic. r 2 =0.40, F 1,6 =3.36, p= Strong and Consistent Preferences Human preferences, as indicated by photographic representation in books, differed greatly among types of penguins. The page area devoted to the most preferred type was more than an order of magnitude greater than that of the least

7 preferred types, and the three most preferred types accounted for more than 80% of the page area occupied by penguin images. Such preference differences are striking considering the similarity of penguins, and indicates that large differences in human aesthetic preference can be based on minor differences in appearance. These preferences were unlikely to be due to anything other than physical traits of the penguins, as photographs with extraneous factors were excluded. Landscape is a particularly likely confounding factor because humans appear to enjoy scenes of the Antarctic, where some, but not all, penguin morphospecies occur. However, I excluded photographs in which landscape was the primary subject. Furthermore, using page area occupied by the images of the penguins themselves (i.e., not including surroundings) as the measure of representation largely removes the influence of background. By this measure, representation of the most preferred penguin type was greater than indicated by numbers of photographs alone, suggesting that the penguin itself was preferred. Finally, two antarctic types, Adel and Chin, were among the least represented. The robust similarity in representation of the eight morphospecies across different authors and publishers indicates that these aesthetic preferences may be widely shared, at least among people of western cultures. Universal aesthetic preferences for broad categories of phenomena, such as bright flowers, sunsets, and savannas, are wellknown (Kellert, 1996). Results of this study suggest human preferences among very similar animals may also be widely held and, perhaps, predictable. The widespread popularity of the recent film, March of the Penguins (Warner Independent Pictures, 2005), featuring Emperor (Apte) penguins, may be due, in part, to the choice of a universally appealing morphospecies as its subject. Why Do We Like Some Penguins More Than Others? Aesthetic appeal of penguins as determined in this study was best explained by amount of warm color; the more bright red or yellow coloration a morphospecies had, the more it was preferred. Heightened attractiveness may result from the color itself or its contrast with a black and white background. Evidently the appeal of penguins with warm color is known in the world of marketing: a recent clothing advertisement depicted Sphen penguins (little warm color) to which orange and yellow coloration was added (Diradourian, 2003). Bright color is also associated with human preference for invertebrates (Kellert, 1993a). However, some of the animals humans find most appealing the panda, elephant, and zebra, for example have very little color. Thus, warm color is not universally associated with human preference for animals. Preferences for penguins were not well explained by size or neoteny, traits found to influence human preference for other types of animals. Humans find large animals appealing (Coursey, 1998; Kellert, 1996; Morris, 1967; Ward et al., 1998), and large animals such as elephants, whales, and horses are often cited among the most popular. In this study, penguin size was positively correlated with representation, but was not a significant factor when warm color was included in the analysis. Although the largest morphospecies was the most represented, one of the smaller morphospecies, Cres, was the second most represented. It is possible that size may be a significant determinant of preference when viewing actual penguins (as opposed to photographs) and animal size can be more accurately assessed. Alternatively, size differences may not influence human preferences among animals of approximately similar size. Humans also tend to prefer animals with apparently neotenic features, such as relatively large head, flat face, and large eyes (Lorenz, 1971). This preference has been identified as an explanation for the popular appeal of the panda (Morris and Morris, 1966). It may also explain the progressive neotenization and simultaneous growth in popularity of Walt Disney s Mickey Mouse, who evolved over the course of 50 years from a long-snouted beady-eyed rodent to the big-headed, big-eyed icon adored by millions (Gould, 1980). Among penguins, however, neoteny did not influence preference, and the weak correlations between preference and measures of neoteny were the reverse of expectation. The most preferred penguin type (Apte) was the least neotenic, having the smallest head, longest bill, and inconspicuous eyes. The type with the largest apparent eye (Adel) was poorly represented. Other factors that may influence human preference for some animals also did not apply to preferences among penguins. Cultural familiarity (Randall, 1986) appeared to be unimportant, as the familiar Adel penguin was much less represented than the relatively unfamiliar Cres penguins. Degree of imperilment or rarity (Czech et al., 1998) also was unrelated to representation. This was not surprising, because members of the public probably could not distinguish levels of imperilment among penguin species. Thus, it appears that different cues influence human preferences among different life forms. While size and neoteny are often important, and familiarity and rarity may sometimes play a role, this study found that only amount of warm color influenced human preferences among penguins. Conservation What lessons for conservation can be drawn from these results? First, human preferences discriminate at a very fine scale, and conservationists must be aware of the potential

8 for minor features of organisms to strongly influence human preferences. Human preferences among different types of organisms have biased the disposition of conservation resources toward large charismatic species (Coursey, 1998) and more attractive vertebrate groups (birds, mammals, and fish; Czech et al., 1998). The results of this study indicate the potential for similar bias within groups of related species. An example of such within-group bias may occur among imperiled California native plants, where aesthetic preferences appear to skew representation of species in ex situ collections (McNamara, 2005; McNamara and Stokes, in prep.). Conservationists must be vigilant to the potential for bias, and actively address it, for example, through attention to conservation effort and promotion of conservation of less attractive taxa. Aesthetic appeal of organisms can work against conservation in other ways as well. Appealing exotic species present difficult conservation dilemmas in part because of popular sentiment in their favor. The controversies over removal of introduced mountain goats (Oreamnos americanus) from Olympic National Park in Washington state (Hutchins, 1995) and eucalyptus trees (Eucalyptus globulus) from Angel Island, California (Boyd, 1997) are well-known examples. Likewise, continued intentional introduction of attractive but invasive horticultural plants is a consequence of human preferences. Public preferences must be considered when developing exotic species management strategies and policies. At the same time, aesthetic appeal is a powerful motivator for conservation. The appeal of penguins and other popular animals such as tigers, pandas, etc. has clearly benefited conservation efforts for those species and others that occur in their habitats. Of course, the attractiveness of organisms should be an important consideration in identifying species on which to focus public attention. Beyond that, an understanding of aesthetics may be used to reveal the appealing qualities of poorly known species. For example, microphotography of invertebrates to effectively display their vivid colors may be a way of increasing their public appeal. More generally, as one of the primary determinants of human preferences, aesthetic appeal is one of the strongest potential motivations for conserving biodiversity. But its power remains latent in people who have not experienced biodiversity and will not miss species because they never experienced them. Providing opportunities for the public to experience biodiversity through images, exhibits, and direct contact is an important means of raising awareness and support for conservation (Stokes, 2006). Important as aesthetic appeal may be, this study also indicates that aesthetic preferences alone are not sufficient to inform conservation effort. Preferences for penguins were not related to level of imperilment and some of the most imperiled types were the least preferred. Rarity or imperilment can increase the value assigned to species by the public (Czech et al., 1998), but only if species rarity is known. It is doubtful that differences in imperilment among penguin species were perceived by the public, and so imperilment could not influence preference. Such is probably the case for most imperiled species: their precarious situation is unknown to the vast majority of people. An obvious implication is that conservationists must convey information regarding endangerment of species to the public. The public must also be better educated about other values of biodiversity besides aesthetic value. The vast majority of organisms likely to become extinct in the near future are invertebrates, a group with great ecological value (Wilson, 2002) but generally low appeal to humans (Kellert, 1993a). Education and increased ecological literacy may increase the degree to which the public values the ecological functions of species (Czech et al., 1998; Montgomery, 2002). The aesthetic value of biodiversity is important in its own right, and is one of the reasons often given for conservation of biodiversity (Kiester, 1997). Those who would protect biodiversity must better understand aesthetic value, along with other biodiversity values such as utilitarian and ecological, to incorporate it into the calculus of conservation priorities. Many types of biodiversity values will differ widely among different people. For example, hunters are likely to assign very different utilitarian values to some species than will non-hunters (Kellert and Berry, 1980). Similarly, values may differ depending on whether people own land (Brook et al., 2003) or engage in recreation (Horne et al., 2005) where biodiversity protection is needed. Reconciling such disparate values adds to the difficulty of prioritizing conservation actions. The consistency of preferences across individuals shown in this study suggests that at least with respect to aesthetics, there may be significant agreement regarding the value of species. This may prove to be a useful commonality a possible basis for constructing broadly acceptable conservation priorities and policies. When conservationists think about conserving biodiversity, they tend to consider the biological entities themselves and their conservation needs (e.g., habitat requirements of species, the nature of threats, etc.). The focus is on the things to be protected. Considered less is the other half of the conservation equation, the people who will decide whether the objects of conservationists interest are worth protecting. The values of the humans who will or will not provide the political and social resolve to bring about conservation are vitally important. Along with understanding and protecting the life forms that are imperiled, conservationists must try to understand and inform the humans on whom the success of biodiversity conservation depends.

9 Acknowledgments Debbie Chiurco, Lily Douglas, and Andrea Freeman helped with data collection and refining the methodology. I thank Debbie Chiurco and Amy McKendry for valuable discussions of the ideas contained in the paper. I also thank Amy McKendry for her helpful critical review of the manuscript. References Adobe Systems (2002). Photoshop 7.0. Adobe Systems Incorporated. Bishop, R. C., and Heberlein, T. A. (1979). Measuring Values of Extramarket Goods: Are Indirect Measures Biased? American Journal of Agricultural Economics 61: Boersma, P. D., and Stokes, D. L. (1995). Conservation: threats to penguin populations. In Williams, T. D. (ed.), The Penguins, Oxford University Press, Oxford, pp Boyd, D. (1997). Eucalyptus removal on Angel Island. California Exotic Pest Plant Council 1997 Symposium Proceedings, 1 3. Brook, A., Zint, M., and De Young, R. (2003). Landowners Responses to An Endangered Species Act Listing and Implications for Encouraging Conservation. 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