Comparing interpretive methods targeting invasive species management at Cumberland Island National Seashore.

Sharp, Ryan L. ; Larson, Lincoln R. ; Green, Gary T. 等

Introduction

Public land management agencies are responsible increasingly for incorporating public input into decision-making processes. Although legislation such as the National Environmental Policy Act (NEPA) mandates public consultation on important issues, land managers often struggle to reconcile discrepancies in public perceptions and desires with sound scientific management principles (Christensen et al., 1996; Cortner & Moote, 1999). Effective education programs may help to resolve this dissonance. Research suggests that interpretive programs designed to increase public understanding and appreciation of important environmental issues can provide critical support for management actions in protected areas (Bright, Fishbein, Manfredo, & Bath, 1993; Marion & Rogers, 1994; Powell & Ham, 2008). Furthermore, general approaches to conservation--including those centered on education and interpretation--rarely incorporate an evaluation component (Ferraro & Pattanayak, 2006). More research is needed to help public land managers identify optimal, cost-effective strategies for educating the public about critical land management issues, minimizing human impacts, and influencing stewardship actions (Coble et al., 2005; Hughes et al., 2009).

Evaluating Interpretive Approaches

Although education can occur in many places (e.g., websites, news outlets, schools), studies suggest that on-site interpretive programs often have the greatest impact on participants' knowledge, awareness, and attitudes (Henker & Brown, 2011). Typically, protected area managers will employ two methods of reaching visitors: interpersonal and non-personal communication (Marion & Reid, 2007). Interpersonal communication (e.g., interpretive programs) consists of face-to-face interactions with visitors that allow for two-way communication. This method, often preferred because it facilitates personal contact with visitors (Knudson, Cable, & Beck, 2003), is difficult to consistently implement due to the high cost of training interpreters and staffing interpretive sites (Munro, Morrison-Saunders, & Hughes, 2008). Non-personal communication (e.g., flyers, brochures) enables interpreters to reach a broader audience, but this approach is relatively inflexible and cannot be adapted easily to meet the needs of individual visitors. Because non-personal communication generally requires visitors to create their own meaning from the material presented, park managers often see it as a less desirable form of education (Hughes, 2004). However, because of its comparatively low cost, non-personal forms of interpretation typically dominates visitors' experiences (Knudson, Cable, & Beck, 2003).

Although the advantages and disadvantages of various interpretive methods are well established (e.g., Ham, 1992), evaluating the effects of these interpretive approaches on visitors has proven to be difficult. Some authors have argued that the intangible, abstract, and emotional connections inspired by interpretation cannot be captured by traditional evaluation approaches (Dustin & McAvoy, 1985). Other authors have lamented that evaluation efforts rarely probe visitor understanding of key messages and the influence of these messages on visitor beliefs (Beckmann, 1999; Hughes et al., 2009). Studies that have demonstrated quantifiable, concrete, interpretation-mediated changes in visitor knowledge, attitudes, and behavior have focused on the complete experience and not specific delivery methods (e.g., Powell & Ham, 2008; Zeppel & Muloin, 2008). Unfortunately, little research has investigated the educational and transformative value of specific interpretive methods and media on visitors (Henker & Brown, 2011). Authors have also acknowledged that interpretive outcome assessment is absolutely necessary for managers who want to develop programmatic improvements and refine their current understanding of interpretive best practices (Coble et al., 2005; Silverman & Barrie, 2000).

In general, effective interpretation involves messages that are enjoyable or entertaining; relevant to the target audience, organized in a clear and concise manner, and thematic in way that promotes factual understanding, intellectual growth, and emotional connections (Ham, 1992; Ham & Weiler, 2002). Once these conditions are satisfied, both interpersonal and non-personal forms of communication can be successful. In fact, research suggests that the interpretive delivery method may not be as important as the content and context of the message and the general nature of the experience (Wiles & Hall, 2005; Winder & Roggenbuck, 2000). For example, the influence of flyers and brochures on visitor knowledge and attitudes depends on how they are distributed. Flyers obtained independently by visitors at a brochure stand have a reduced impact compared to flyers personally delivered by staff member at the park or protected area (Moscardo, 1999; Oliver, Roggenbuck, & Watson, 1985). However, other research has shown that certain interpretive approaches--notably ranger-led programs--are far more effective than others at helping visitors develop meaning connections with resources (Coble et al., 2005; Henker & Brown, 2011).

If all factors are equal, what type of interpretive message is more powerful? Do the relative benefits of interpersonal communication justify the costs, or are cheaper non-personal approaches equally effective at influencing visitor knowledge, attitudes, and behavior toward environmental issues? To address these questions, this study evaluated the differential effects of two interpretation methods (a non-personal, visual-based flyer and an interpersonal, audio-based talk) on the cognitive and affective components of visitor's experience within a specific context. In particular, this study focused on the escalating issue of invasive species management at Cumberland Island National Seashore, Georgia.

Case Study Context: Public Perceptions of Invasive Species Management

Invasive species are an issue facing ecosystems throughout the world and are considered to be a major threat to biodiversity across the planet (Bremner & Park, 2007; Gurevitch & Padilla, 2004; Lockwood, Hoopes, & Marchetti, 2008). As economic globalization increases the movement of species via trade, transportation, travel, and tourism, the invasive threat will continue to grow (McNeely, 1996; Pimentel, Zuniga, & Morrison, 2005). Preserving native species diversity and natural ecological processes has become a full-time endeavor for the U.S. National Park Service (NPS) as the fight to ward off invasive species intensifies (Houston & Schreiner, 1995; Sellars, 1997). In fact, the NPS has acknowledged the important role that public education campaigns can play in the fight against invasive species (McNeely, 2001).

Cumberland Island National Seashore (CUIS), a unit managed by the NPS, is a prime example of an area facing the invasive species infestation issue. Cumberland Island has some very visible and destructive invasive species, such as feral hogs and horses, introduced by previous island inhabitants, that have caused a great deal of ecological damage (Dilsaver, 2004). The feral horses, in particular, represent a contentious and controversial issue for CUIS managers. Although the horses negatively impact the sensitive barrier island ecosystem, many visitors come to CUIS with the specific goal of viewing horses (Kirkpatrick, 1995). This situation creates a challenging management conundrum. In addition to the feral horses and hogs, a new invasive fungus from Asia is killing red bay and sassafras trees at an alarming rate with no containment method currently available (Fraedrich et al., 2008). Furthermore, invasive plant species such as bamboo and the tung oil tree are altering permanently the coastal landscape. The CUIS managers have recognized the negative economic and environmental impacts of invasive species and have stated that invasive feral animals and exotic plants will be managed "to the point that their threat is negligible" (NPS, 1984). However, this aggressive management strategy towards invasive species can only succeed with public support (Bremner & Park, 2007). If managers do not incorporate visitors' perspectives into the management planning process, they run the risk of losing public support for invasive species policies and control measures (Nimmo & Miller, 2007).

The CUIS context therefore presents an ideal situation for examining public response to various forms of interpretation targeting a contentious environmental issue. Because CUIS is primarily accessibly by ferry, the highly regulated access points create a controlled mechanism for exposing visitors to interpretation treatments and evaluating their response. Although the education outcomes examined in this study focused on invasive species, results could help to refine and adapt similar interpretation programs targeting other natural resource management issues occurring across the country.

Outcome Variables

Knowledge & Awareness

Knowledge and understanding of ecological topics is required to make informed decisions about protected area management. Visitors that have a greater awareness of ecological issues are generally more likely to support management decisions (Wiles & Hall, 2005). Educational and interpretive programs are proven vehicles for enhancing visitor awareness of salient issues (Powell & Ham, 2008; Zeppel & Moulin, 2008). Background knowledge also mediates the connections visitors develop with on-site information. For instance, Roggenbuck et al. (1982) found that visitors with little prior knowledge upon arrival at a protected area were more likely to have an increase in knowledge following their visit. However, well-educated park visitors are often more receptive to educational and interpretive messages (Hendee & Dawson, 2002). Given these somewhat contradictory results, more information is needed to understand the effects of on-site interpretation on visitors' knowledge and awareness. Hence, this study examined the effects of interpretation on visitors' general knowledge of the invasive species issue and specific knowledge of invasives found at CUIS.

Attitudes

In addition to increasing awareness, educational and interpretive programs should aim to influence visitors' attitude and emotional attachment to an area or a particular issue (Wiles & Hall, 2005). These affective links can help visitors develop a stronger sense of environmental stewardship (Madin & Fenton, 2004). Although Ham (2007) suggested that many interpretive contacts are much too short to have an effective impact on visitor's attitudes, other studies have shown that object-specific attitudes are fluid and can be changed by individual contact with effective interpretive messages (Kim, Airey, & Szivas, 2011; Petty & Cacioppo, 1986). Individuals' initial attitudes especially are susceptible to change if they become attached to a stronger attitude or belief (Williams et al., 2002). These patterns emerged from the work of Wiles and Hall (2005), who discovered that individuals with less prior knowledge and weaker attitudes toward an object were more likely to experience program-mediated change. This discovery has important implications for public land management. Through educational and interpretive programs, managers have an opportunity to increase awareness, transform attitudes, and promote an enhanced land ethic in hopes of garnering support for a proposed management action (Marion & Reid, 2007). Hence, this study also examined the effects of interpretation on visitors' attitudes toward native and non-native species.

Management Preferences

Public land management occurs in an integrated social environment. Managers make decisions that not only influence natural resources, but also impact how visitors experience these resources. Public input into the decision making process is therefore critical. However, rampant discord among scientists, land managers, and the public often complicates this process. While scientists and managers usually act based on scientific evidence, the public often responds to issues based on emotional attachments (Rikoon, 2006). Consequently, interpretive programs must acknowledge and respond to these emotional attachments and environmental value orientations (McFarlane & Boxall, 2000). By shaping beliefs, attitudes, and social norms, educational and interpretive programs can alter stakeholders' management preferences and potential acceptance of management policies (Absher et al., 2008). Additional research would help to clarify the effects of different interpretive approaches on these management-oriented perspectives. Hence this study also examined the effects of interpretation on visitors' support for various invasive species management options.

Statement of Purpose

The purpose of this research was to assess the effects of two interpretive programs (a flyer and a ranger-led talk) on visitors' knowledge of, attitudes toward, and support for invasive species management at CUIS relative to a control group. By comparing mean scores of these target outcome variables for visitors exposed to different interpretive treatments, this study hoped to identify optimal strategies for educating visitors and provide a foundation for informed participatory decision-making processes regarding invasive species management on public lands.

Methods

Visitor Education Programs

The two interpretive programs examined in this study featured identical content delivered in unique ways. The visual interpretive method (hereafter "flyer") consisted of a two-sided, 8.5-inch by 11-inch black-and-white, illustrated, tri-fold flyer that was distributed immediately to visitors as they exited the dock and arrived on the island (Appendix A). The reading level and general comprehension of the flyer was tested with several audiences (e.g., university students, national park visitors) prior to implementation. The audio interpretive method consisted of a brief five- to seven-minute ranger talk (hereafter "talk") that was conducted at the unloading zones immediately after island visitors left the ferry (Appendix B). To maintain consistency, each iteration of the talk was conducted by the same interpreter. Both the talk and the flyer contained the same theme: a focus on the invasive species issue in a global, national, and local context, including current challenges at CUIS. Both interpretive approaches were also designed based on Ham's (1992) guidelines for effective interpretive messages: enjoyable, relevant, organized, and thematic. Visitors in the control group did not receive either form of intentional interpretive treatment when they arrived at the island.

Data Collection

A quasi-experimental, static groups comparison approach was used to evaluate the effects of these two distinct interpretive strategies on a random sample of visitors to CUIS (N=1,093). Arriving visitors on predetermined days from April to September of 2008 were randomly assigned to one of three groups: visitors receiving an interpretive flyer (n=363), visitors receiving an interpretive talk (n=320), and visitors who did not receive any formal interpretive treatment focused on invasive species management (n=410). At the conclusion of their visit, every third CUIS visitor over age 18 was asked to complete a 10- to 15-minute intercept survey while waiting at the ferry dock or on the boat returning to the mainland. This administration approach allowed ample time for survey completion (response rate = 93%). Data were collected via a stratified random sampling procedure to help ensure adequate coverage across days of the week, hours of the day, and dock sites (two separate ferry docks) within the park.

The public perceptions survey instrument was based upon existing literature (Bremmer & Park, 2007; Brooks et al., 1999) and targeted cognitive (What do visitors know about invasive species?) and affective outcomes (How do visitors feel about invasive species?) related to dimensions of invasive species management. Questions were with categorical, multiple-choice, open-ended, or Likert-type responses guided by the tailored design method for survey construction (Dillman, 2007). Visitors' basic concept of the term "invasive species" was measured with a single multiple-choice item. General knowledge-related items (11 total) were measured on a scale from 1 = "not at all aware or familiar" to 3 = "very aware or familiar." Visitor awareness of specific invasive species on CUIS (six total) were also measured on a three-point scale where 1 = "I don't know what this is," 2 = "I know the name, but I didn't know it was invasive," and 3 = "I know what this is and I know it's an invasive species." Attitude-related items (14 total) were measured on a scale from 1 = "strongly disagree" to 5 = "strongly agree." Visitors' management preference items (12 total) were assessed on a scale from 1 = "unacceptable in all cases" to 5 = "acceptable in all cases." The final instrument also included socio demographic questions and information related to visitors' general outdoor recreation preferences and experience use history at CUIS and other NPS sites.

Data Analysis

Data were analyzed in several phases. Because pre-visit surveys were not conducted, the random allocation of visitors to each of the treatment groups was confirmed before program effects were examined. Group characteristics were compared using frequencies and chi-square differences. Next, survey responses were checked to ensure that visitors who were exposed to a specific educational treatment were aware that they had received that particular information--validating the quasi-experimental group assignments. Finally, general effects of the educational treatments were examined using a priori analysis of variance (ANOVA) contrasts comparing visitors in both treatment groups (talk and flyer) to visitors in the control group. Treatment effect size (r) was also examined for the contrasts using the formula r = [square root of [[t.sup.2] / ([t.sup.2] + df)]], where r = 0.5 was indicative of a large treatment effect, r = 0.3 represented a medium effect, and r < 0.1 signified a small effect (Cohen, 1988). For variables where the effects of the educational treatments were significant in the ANOVA, specific effects of the talk and flyer were compared using post hoc pair-wise tests with Bonferonni adjustments.

Limitations

Several limitations affect the inferences that can be made from this research. First, the feasibility of implementation and park restrictions prevented this study from using a within-subjects design. Although this type of pre-post method--which controls for respondents' initial levels of knowledge and attitudes--would have been optimal (DiMauro & Dietz, 2001), it was assumed that the randomly selected control group used in this quasi-experimental approach represented the views and attitudes of visitors not exposed to the interpretive treatments (i.e., the baseline levels).

Second, the population of visitors sampled at CUIS does not necessarily represent the general public at large. Despite this limitation, however, general demographic information suggested that the CUIS sample was similar to other samples in studies involving NPS visitors. The CUIS visitors were fairly homogenous (typically highly educated, high income, and white), and interpretation methods focused on other areas, audiences, or contentious issues might yield different results. In fact, Ballantyne et al. (1998) recommended that interpretive messages and media should be targeted specifically to meet the needs of unique groups. Interpretation that works in one situation may not be as effective in other contexts.

Third, the interpretive messages used in this project focused on an exceptionally controversial issue. Many of the survey questions focused on the island's feral horse population, and feral horses are a sensitive topic at CUIS (Sharp et al., 2011). Hence, the cognitive dissonance that many visitors experience can be problematic. While many visitors come to CUIS to see the feral horses, they also recognize the destructive potential of the Island's unique, non-native attraction. Hence, some survey responses may have been skewed as visitors struggled to simultaneously respond to the scientific information presented to them in relation to their personal beliefs and attitudes. However, this complex situation highlights the need for effective interpretive programs and assessments that evaluate their efficacy.

Results

Defining the Treatment Groups

To compare the effects of the two interpretive treatments relative to the control group, this study had to first confirm that the group assignments were unbiased. Data showed that, with the possible exception of length of stay, groups essentially were homogenous in terms of demographics and experience use history (Table 1). Therefore, it was assumed that a large portion of any observed differences in visitor knowledge of, attitudes toward, and preference for invasive species management would be due to the various interpretive treatments.

Overall, the CUIS visitors consisted of an equal mix of males and females. A vast majority of the visitors were white. The mean age of visitors was approximately 40 years old, and over half of the participants reported education levels that included an advanced degree. This elevated educational level is higher than the general U.S. population but consistent with national park visitors in general (NPS, 2002). A majority of CUIS visitors had been to the island before, and most had visited at least one other NPS site in the past five years. About one-half of all visitors said they had been exposed to some type of information about invasive species in the media during the past year.

Validating Treatment Group Assignments

Although limited access to CUIS helped to ensure that all visitors entering the park on a particular day were exposed to one of the designated treatments, this assumption needed to be validated. To confirm the group assignments on particular days, a survey item was checked that asked participants, "During your visit to CUIS, from which of the following sources did you receive information regarding invasive species?" In general, results suggested that the perceived group assignments accurately reflected most visitors' exposure to interpretive programs (Table 2). However, not all visitors in the flyer and talk treatment groups acknowledged that they had received educational information or materials in that particular format.

Effects of Interpretive Treatments

Knowledge of Invasive Species.

When asked to choose the best description of an invasive species, 41.3% of visitors selected the correct response, "species foreign to CUIS that out-compete native species." Visitors exposed to the talk (50.3%) and flyer (40.5%) interventions chose the correct response more often than visitors in the control group (39.8%), [chi square](df=8) = 19.1, p = 0.014, however the difference between the flyer and the control group was minimal. About twice as many visitors in the control group (7.6%) were not sure how to describe an invasive species, compared to only 3.9% of visitors in the treatment groups.

Visitors who experienced the interpretive talk scored higher than visitors who received the flyer on all of these knowledge items, and significantly higher than visitors in the control group (Figure 1). Mean scores for general knowledge items ranged from 1.73 to 2.34, indicating that most visitors were only slightly aware of invasive species and their impacts. Visitors' general knowledge of invasive species was slightly affected by the interpretive treatments when compared to the control group. For example, the interpretive interventions appeared to significantly positively affect a visitors' familiarity with why species are considered invasive [t(1076) = 2.69, p = 0.007, r = 0.08], why the removal of invasive species is important to the local ecosystems, t(1073) = 2.43, p = 0.015, r = 0.07, effects of invasive species on native plants and animals, t(1068) = 2.39, p = 0.017, r = 0.07, and awareness of invasive species' contribution to the listing of threatened and endangered species, t(1077) = 2.21, p = 0.027, r = 0.07. However, visitors exposed to the interpretive programs were not any more aware of the NPS's mission in regards to controlling invasive species than visitors in the control group [mean score = 1.73, t(1071) = 0.86, p = 0.390, r = 0.03].

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The interpretive treatments also appeared to affect visitors' knowledge of specific invasive species. Although knowledge of less conspicuous invasive species such as ambrosia beetles, tung oil trees, and privet was not affected by the treatments, visitors exposed to either the talk or the flyer indicated an elevated awareness of feral horses, t(1063) = 2.30, p = 0.022, r = 0.07, feral hogs, t(1060) = 5.57, p < 0.001, r = 0.17, and bamboo, t(1054) = 2.00, p = 0.046, r = 0.06, relative to the control group. Both treatments appeared to affect visitor knowledge of these species to an approximately equal degree (Figure 2). It should be noted that, although many different invasive species were described in the text, feral horses, feral hogs, and bamboo were the only invasive species pictured on the flyer.

Attitudes Toward Invasive Species.

An exploratory factor analysis (principal axis factoring with oblique rotation) was used to reduce the attitude items on the survey into two primary constructs (see Sharp et al., 2011 for factor loading results): absolute ecocentric items (three total) reflected a belief that all species--even invasives--have a right to persist and should not be controlled by humans; adaptive ecocentric items (eight total) reflected a belief that some degree of human intervention is necessary to manage invasive species to protect native ecosystem integrity. Contrasts showed that the interpretive treatments did not have a significant effect on visitors attitudes on either the absolute ecocentric, t(1073) = 0.53, p = 0.598, r = 0.02, or adaptive ecocentric, t(1075) = -0.13, p = 0.900, r = 0.00, subscales. In fact, even when examining individual items, significant differences between the treatment and control groups were not evident, t(1059) > 1.78, p > 0.075, r < 0.05.

Support for Invasive Species Management.

An exploratory factor analysis (principal axis factoring, oblique rotation) was also used to reduce the management preference items on the survey into three major constructs (see Sharp et al., 2011 for factor loading results): leaving invasive species alone (one item), adaptive on-site management of invasives (seven items), and complete eradication of invasives (two items). Contrasts showed that, relative to the control, the interpretive treatments did not have an effect on visitor preferences for two of the management categories--leaving invasives alone, t(1052) = 0.13, p = 0.900, or managing invasives onsite, t(1070) = -0.47, p = 0.638. However, management preference scores for the "eradicate invasives" items were significantly different between the treatment and control groups, t(1057) = -2.33, p = 0.020, r = 0.07. Contrary to expectations, visitors in the control group actually displayed a greater likelihood of supporting complete eradication of invasive species from Cumberland Island than visitors who were exposed to either the talk or the flyer (Figure 3).

Visitors who listened to the talk were more likely to support any type of active invasive species management than visitors who received the flyer. In fact, visitors in the flyer treatment group only scored higher than the visitors in the talk treatment group for the "leave invasives alone" option. Mean differences (MD) between the talk and flyer treatments (talk mean - flyer mean) were the most obvious in the post hoc pair-wise comparison tests for the following items: sponsoring invasive hunts (MD = 0.35, p < 0.001), managing non-natives introduced by humans (MD = 0.18, p = 0.028), spending money to control invasives (MD = 0.175, p = 0.018), and eliminating invasive animals (MD = 0.303, p = 0.002). In all cases, visitors who listened to the talk were significantly more likely to support interventions than visitors who received the flyer. These item-specific differences between the talk and flyer treatment groups were also reflected in the overall subscale scores for on-site management (MD = 0.21, p = 0.002) and complete eradication (MD = 0.22, p = 0.047) of invasive species.

Discussion

Interpretive Treatments vs. Control

Based on existing research (e.g., Roggenbuck et al., 1991), it was hypothesized that visitors who received either interpretive treatment would exhibit an increase in knowledge-based survey scores relative to the control group. As predicted, visitors exposed to the interpretive treatments scored slightly higher than visitors in the control on both the general and specific knowledge scales. However, even after exposure to interpretive messages, many visitors remained unsure of the invasive species concept and unfamiliar with different types of invasive species--a result consistent with previous findings (McNeely, 1996). The most significant positive treatment effects were observed for the CUIS-specific knowledge and awareness items. This result supports previous research suggesting that interpretive messages are most powerful when they are relevant for a particular audience (Powell & Ham, 2008). The interpretive program's positive effect on public knowledge and awareness especially is encouraging considering the declining environmental literacy rates across the United States (Coyle, 2005; Louv, 2005). If the public is more aware of environmental issues such as invasive species, perhaps they will become more involved in the decision making process and develop and stronger sense of stewardship toward public lands (Dettmann-Easler & Pease, 1999; Orams, 1997).

Contrary to predictions, the interpretive treatments did not appear to have a significant effect on visitor attitudes. These results suggest that short-term interventions such as flyers and brief talks may not be adequate mechanisms for stimulating affective change, supporting earlier research (DiMauro & Dietz, 2001; Ham, 2007). For example, surveys revealed that about 30% of visitors who had been exposed to interpretation (either the flyer or talk) did not realize it. For greater effects on cognitive domains such as attitudes, a more active form of message (e.g., discussion groups, repeated mailings, sustained educational campaigns) may be necessary (Hughes et al., 2009; Marynowski & Jacobson, 1999). Often, the frequency of the message may be more important than the content of the message.

Significant differences between the treatment and control group were observed for one management option: complete eradication of invasive species. Surprisingly, visitors exposed to the interpretive messages were less likely to support this option than visitors in the control group. This could be attributed to the fact that although visitors in the treatment groups were given information about alternative means of invasive species population control, visitors in the control group may have viewed complete removal as the only feasible option. These responses demonstrate how various forms of interpretive messages can help managers build a case for adaptive management. However, the effect of these messages should be closely monitored so unexpected consequences do not emerge.

Flyer vs. Talk

When comparing the efficacy of the two different interpretive strategies, results showed that the interpretive talk had a stronger effect on general visitor knowledge than the educational flyer. The beneficial effects of both interpretive methods on specific knowledge of invasive species at CUIS were approximately equal. The awareness scores for three invasive species--feral horses, feral hogs, and bamboo--especially were high. These species were all pictured on the flyer, highlighting the importance of visual cues in non-personal interpretive messages (Moscardo, 1999; Munro, Morrison-Saunders, & Hughes, 2008).

Differences in attitude scores between the treatment groups were not evident, but management preference scores revealed a recurring pattern. Visitors who received the interpretive talk were significantly more likely to support some type of adaptive on-site invasive species management than visitors who received the flyer, supporting a link between ranger-led (i.e., personal interpretation) programs and stewardship intentions observed in previous studies (e.g., Henker & Brown, 2011). The enhanced value of the interpretive talk approach could be due to several factors. Arriving visitors assigned to the "talk" group were required to listen to the ranger, whereas visitors had no obligation to read through the entire flyer. (In fact, several were directly discarded on the ground at the dock site.) This discrepancy emphasizes the value of enhancing visitors' experience through interpersonal communication and interaction with a somewhat captive audience (Henker & Brown, 2011; Knapp & Benton, 2004). The talk provided an opportunity to interact with visitors and check for understanding, making certain the central theme of the interpretive message was conveyed. Furthermore, the interpersonal talk helped to situate visitors. A non-personal flyer allows visitors to build upon pre-existing schema for beliefs and attitudes that may be inappropriate, inaccurate, or out of context. For controversial issues where the NPS adopts a particular stance, a talk may be a more appropriate interpretive method.

On the other hand, the interpretive flyer approach conferred a potential advantage that was reflected in the management preference scores. The flyer's message included information in an accessible, easy-to-read format that visitors could reference at any point during their trip. As visitors congregated at the Island's docks awaiting departure, they had ample time to review the flyer at their discretion. Perhaps visitors who received the flyer and referred to it multiple times during their visit developed a more positive emotional association with the focal species (feral hogs and horses), which could explain their decreased level of support for complete eradication. In any case, provision of a temporal window for free-choice learning to occur is a distinct advantage of the flyer approach (Falk, 2001). While the talk may have seemed like an intrusive burden to many visitors, the flyer represented a more subtle way to convey a similar message. Unfortunately, the non-personal delivery format of the flyer also enabled its messages to be misconstrued. Although personal methods such as ranger programs occasionally lead to misinterpretation as well, these errors can generally be controlled as speakers adjust and adapt to audience cues to ensure delivery of accurate information. The different effects of both the talk and flyer highlight a well known pitfall of interpretation--messages that address non-captive audiences and rely on voluntary participation are highly variable in their success (Hammitt, 1984).

Recommendations

Overall, visitor responses to the two interpretive strategies yielded some hope with respect to the educational impact of interpretive messages regarding public land management. The audio-based interpretive talk appeared to have a stronger effect on the knowledge, awareness, and management preferences of CUIS visitors than the visual-based interpretive flyer. To increase the likelihood that information in the visual treatment is consumed and absorbed, the flyer could be revised to include less detailed information, more pictures, and more cohesive theme highlighting the devastating impacts of conspicuous invasives at CUIS. To improve the efficacy of the audio treatment, visitors could be briefed on the

island's invasive species (and other important park information) during their 45-minute ferry ride. This efficient use of time would capitalize on an inquisitive, captive audience and reduce the frustration and anxiety associated with a mandatory information session upon arrival. Research has shown that a non-personal form of audio communication--audio tours using podcasts and MP3 technology--could also be an effective way to connect with visitors (Henker & Brown, 2011; Novey & Hall, 2006). The development of podcasts available on the park website or interactive visitor center kiosks would make information available at the visitor's discretion. This approach could allow for repeated exposure to interpretive messages as visitors digest material through multiple views and/or listens, increasing their transformative power.

An integrated interpretive approach may yield the best results. Individuals learn and react to material in different ways, and responses to interpretive media can vary across distinct populations (Ballantyne et al., 1998; Coble et al., 2005; Roggenbuck & Berrier, 1982). Factors such as race/ethnicity (Coble et al., 2005) and previous experience at a site (Hughes et al., 2009) often influence outcomes of interpretive messages. Therefore, a combination of multiple interpretive media and educational messages are likely needed to help managers communicate with diverse visitors. Finally, managers should remember that learning about conservation issues if often a secondary motivation for park visitors (Absher & Graefe, 1997). Interpretive messages should therefore be conveyed in a concise and captivated fashion. Public land management involving controversial problems such as invasive species is inexorably guided by public awareness of and attitudes toward important environmental issues. Interpretive programs and educational campaigns could play a major role in that process, ultimately producing more informed collaborative approaches to public land management decisions.

Appendix A--Invasive Species Audio Group Flyer

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Appendix B--Invasive Species Talk Group Script

* Good (morning, afternoon), my name is Ryan and I would like to take the next three to five minutes to tell you about invasive species.

* Can anyone tell me what an invasive species is? Wait for audience response, gather two to three.

* Great. Invasive species can mean many things to many people, but let's start by defining what an exotic species is:

** An exotic species is one (plant or animal) that is not native to a particular ecosystem, not native being from a different part of the country or from a different country entirely.

** Many of America's staple crops are exotic (or non-native) such as corn, wheat and apples, however, these are not invasive species, simply non-native.

** A species becomes invasive when it begins to outcome native species, replacing them in that particular ecosystem.

** Can anyone name an invasive species they have heard of? Wait for two to three responses.

* The National Park Service defines invasive species as:

** Species that grow and spread rapidly and are free from the natural controls present in their natural lands, such as herbivores, parasites and diseases.

* So why is this important? Invasive species can have a negative impact on the environment in the form of trampling vegetation, out-competing natives species and eliminating future generations by destruction of nest and interrupting the food chain

** Invasives are responsible:

*** For $20 billion per year in economic damage

*** 42% of all species on the endangered species list

*** Covering 2.6 million acres of NPS lands

** The NPS ranks invasive species in front of air pollution, off-road vehicle usage, and visitation pressures as the main threat to the ecosystems of many of its parklands.

** 1,000 species of invasive plants and 500 non native animals.

* Cumberland Island has 66 documented invasive plants such as tung oil tree, privet, and bamboo.

* Cumberland Island has an invasive beetle that carries a fungus that infects red bay trees on the island.

* The horses and pigs were introduced to the island in the 1600s. However the current populations are descended from livestock released on the island in the early 1900s.

** Pigs have been known to eat sea turtle and sea bird eggs on the beach.

** Horses eat the sea oats which are vital for dune stabilization; over forage in the salt marshes reducing critical habitat.

* So what can be done to control invasive species?

** Invasive plant species may be controlled through such methods as the use of herbicide and pulling.

** Invasive animal species may be controlled through contraceptive measures, adoption programs, and managed hunts, among other methods.

* So what can you do to help prevent the spread of invasive species?

** Find out about plants native to your region.

** Check that the plants you are buying for your yard or garden are not invasive.

** When boating, clean your boat thoroughly before transporting it to a different body of water.

** Clean your boots before you hike in a new area to get rid of "hitchhiking" weed seeds and pathogens.

** Don't release aquarium fish and plants, live bait, or other exotic animals into the wild.

** If you plan to own an exotic pet, do your research and plan ahead to make sure you can commit to looking after it.

** Volunteer at your local park, refuge, or wildlife area to help remove invasive species.

** Help educate others about the threat.

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Ryan L. Sharp

Eastern Kentucky University

405 Begley Building

Richmond, KY 40475

[email protected]

Lincoln R. Larson

Daniel B. Warnell School of Forestry and Natural Resources

University of Georgia

Athens, GA 30602

Gary T. Green

Daniel B. Warnell School of Forestry and Natural Resources

University of Georgia

Athens, GA 30602

Sara Tomek

University of Alabama

Box 870231

Tuscaloosa, AL 35487

Table 1. Demographic Composition of Treatment Groups (with
Chi-square Difference Tests)

                                     Treatment Group

Variable                         Control   Flyer   Talk   TOTAL

N                                  404      313    351    1093

Gender                            48.5     49.3    52.7   50.0
(% male)
Age                               37.2     44.9    36.9   39.6
(% under 40)
Race/Ethnicity                    93.5     94.6    92.6   93.6
(% White)
Education                         53.9     59.9    57.6   56.9
(% w/ advanced degree)
CUIS Length of Stay               57.2     71.5    63.6   63.8
(% day use only)
Transportation to CUIS            92.1     96.7    97.8   95.3
(% riding NPS ferry)
Any National Park Visit           60.8     55.6    54.0   57.1
(% visiting in past year)
Any National Park Visit           85.5     86.4    82.9   85.1
(% visiting in past 5 years)
Consumptive Outdoor               42.4     38.6    47.8   42.7
Recreation Participant
(% participating)
Member of Conservation Org.       15.4     15.6    13.2   14.8
(% members)
Invasive Species in Media         52.0     54.8    49.2   52.1
(% exposed to media info on
invasive species in past year)

Variable                         Diff. Stat.

N

Gender                           [chi square](2)=1.4,
(% male)                         p=0.509
Age                              [chi square](2)=6.0,
(% under 40)                     p=0.049
Race/Ethnicity                   [chi square](2)=1.1,
(% White)                        p=20.585
Education                        [chi square](2)=2.8,
(% w/ advanced degree)           p=20.252
CUIS Length of Stay              [chi square](2)=16.8,
(% day use only)                 p<0.001
Transportation to CUIS           [chi square](2)=15.0,
(% riding NPS ferry)             p=0.001
Any National Park Visit          [chi square](2)=3.9,
(% visiting in past year)        p=20.144
Any National Park Visit          [chi square](2)=1.7,
(% visiting in past 5 years)     p=20.423
Consumptive Outdoor              [chi square](2)=6.0,
Recreation Participant           p=0.051
(% participating)
Member of Conservation Org.      [chi square](2)=1.7,
(% members)                      p=0.423
Invasive Species in Media        [chi square](2)=2.1,
(% exposed to media info on      p=0.349
invasive species in past year)

Table 2. Percentage of Cumberland Visitors in Each Assigned
Treatment Group Acknowledging Exposure to Invasive Species
Information from Different Sources During Their Visit

                              Assigned Treatment Group

Variable                       Control   Flyer   Talk
                                 (%)     (%)      (%)

Information from Any Source     29.8     69.1    70.3
Flyer                            2.0     54.3     0.6
Talk                             2.4      1.1    56.6
Other Ranger Talk               26.8     13.8    12.2