Wildlife Impacts on Agroecosystems and Culture: Achieving Integrated Pest Management of Invasive Ungulates in Hawai‘i

1. Quantify economic impacts of invasive, unmanaged ungulates to agriculture in Hawai‘i. Producer surveys (Years 1-2) will assess habitat damage and economic impacts to agriculture from unmanaged, non-native ungulates (deer, sheep, goats, and pigs). Forage and crop loss, decreased livestock production, and consequent economic losses will be identified through survey questions and fieldwork. Statewide economic impacts will be analyzed through a computer modelling system and summarized as a fact sheet.
2. Quantify impacts of unmanaged ungulates on forage production in agricultural landscapes in Hawai‘i. Ecological surveys and fieldwork (Years 1-2) will quantify ungulate numbers through camera traps, comparisons to previous ungulate population models, and measurements of forage biomass loss and forage species diversity.
3. Identify cultural significance of managed and unmanaged ungulates in agricultural landscapes of Hawai‘i. Unmanaged ungulates are hunted throughout the state, and cattle ranching communities revere the paniolo (cowboy) culture. These cultural aspects of the landscape and people will be documented through questions included on the producer economic survey (Year 1), through cultural surveys of multiple stakeholder groups (Year 1), and through individual interviews with ranchers, hunters, and cultural practitioners (Year 1), in order to develop culturally appropriate IPM practices (Objectives 4, 6).
4. Identify culturally appropriate and economically viable methods of control for unmanaged ungulates, in order to improve food security in Hawai‘i. Sustainable meat markets can potentially provide income for producers from both livestock and unmanaged ungulate meat, but hunter-harvested meat resales are limited by inspection and processing options. Ideas for incentivizing strategic ranch fencing, targeted hunting, meat processing, and marketing, will be gathered through stakeholder input during food security focus group workshops (Years 2-3). This information will be used to create  culturally-appropriate, geographically explicit, decision support guidelines for producers seeking IPM practices for their specific locations in regard to control of unmanaged ungulate species (Objective 6).
5. Educate stakeholders and policy decision-makers about the impacts of unmanaged ungulates on economics, agriculture, food security, and ecosystems in Hawai'i. This objective is integrated throughout all objectives, but is detailed under the Education Plan.  
6. Develop decision support guidelines that facilitate stakeholder choices for economically viable and culturally appropriate Integrated Pest Management Practices (IPM) for these ungulate populations, in order to mitigate damage to agricultural lands and ecosystems in the Hawaiian Islands. Island-specific, culturally-appropriate, decision support guidelines, tailored to agricultural product and land manager values, will be developed in consultation with producers and other stakeholders, in order to facilitate choices of IPM practices for their specific locations in regard to control of unmanaged ungulate populations (Years 2-3). Guidelines will be specific to crop type and/or production goals, willingness to allow hunter access, location (to allow for correlated variables such as rainfall, temperature, wild ungulate type and abundance from distribution models), as well as island-specific available actions such as specific hunting associations, county working groups and ordinances, and other geographically-specific information. Based on data collected during this project and the user inputs, the analyses will  identify optimal user-specific solutions that account for social, cultural, and economic variables. Outputs will also direct the users toward island-specific contact information for permitting, state and federal offices that can provide specific types of support to achieve the identified optimal set of actions, hunting associations, and the state and county Game Management Advisory Commissions, which serve as contact points for hunter-focused management solutions.

Materials and Methods

Study location: The economic and cultural survey portions of the study will be conducted across the islands, targeting livestock and crop producers, hunters, fishers, and cultural practitioners and experts. The ecological fieldwork portion of the project will be conducted on private and leased rotationally grazed ranch lands and other agricultural lands. Research will focus on six islands: Hawaiʻi, Kauaʻi, Lānaʻi, Maui, Molokaʻi, and Oahu, with field work on two islands and surveys and interviews across all islands. Each of these islands has unique assemblages of unmanaged ungulates (see map) and unique hunting and agricultural use patterns. We will collaborate with producers and other stakeholders on various islands as follows.

1. Quantify economic impacts of invasive, unmanaged ungulates to agriculture in the Hawaiian Islands (Years 1-2). Producer surveys. Surveys to identify economic impacts will be distributed to agricultural producers across all of the Hawaiian Islands via the Hawaiʻi Cattlemen’s Council, Farm Bureau, and Conservation Districts, targeting managers of ranches and other agricultural lands with a series of questions on stocking rate, unmanaged ungulate presence, attitudes toward wildlife and hunting, crop damage, and perceived economic impacts (positive and negative) of various species. Previous work suggests producers can accurately assess damage (Elser et al., 2019; Tzilkowski et al., 2002) and wildlife experts have expressed confidence in producers’ ability to assess damage (Conover, 1998). Additionally, survey damage estimates will be compared with on-the-ground estimates to verify accuracy. Survey results will be used to calculate direct impacts of unmanaged ungulate and other pest damage, and will inform economic modeling of damage on producer lands using a Regional Economic Modelling Inc. (REMI) system. The survey will also solicit producers’ perspectives about the cultural value of each species of ungulate in the study, and their interest in adopting sustainable production practices, including willingness to pay for reduction of unmanaged ungulates. Interviews will be undertaken with a subset of producers on each island, using snowball techniques to select interviewees until saturation is reached within each stakeholder group, to gain further insights. A fact sheet summarizing the findings and detailing impacts to the state economy will be prepared for distribution to participants, other project stakeholders, policy decision-makers, and the general public (see Education Plan).
2. Quantify impacts of unmanaged ungulates on forage production in agricultural landscapes in Hawai‘i (Years 1-2). Ecological surveys. To determine impacts of unmanaged ungulates (deer, pig, goat, sheep) and to evaluate the relationship between unmanaged ungulate and livestock (managed ungulate) abundance, population surveys will be undertaken for both groups. Field sites will be selected on Hawai’i Island and Maui producer lands. Motion-activated game camera surveys will be utilized to evaluate ecological relationships of unmanaged ungulates and managed livestock on rotationally grazed pastures. Unmanaged ungulate and livestock occupancy and abundance will be correlated with amounts of crop damage reported in the economic survey, and in the case of pastures, quantified through forage utilization plots. Ranch lands will be surveyed for unmanaged ungulates in the spring and fall using motion-activated camera traps distributed every 50m in a rectangular array in two parallel lines of three when domestic livestock are not present. Sites will be selected randomly across altitudinal gradients. Camera traps will be set up in areas that will maximize the likelihood of detections (Risch et al., 2020). Forage utilization by unmanaged ungulates will be quantified using grazing exclusion cages paired with grazed plots (Klingman, et al. 1943; Bonham 2004). Three paired grazing exclusion cages and grazed plots will be randomly established within each motion-activated camera trap at the beginning of each unmanaged ungulate monitoring period. At the end of each monitoring period, biomass will be clipped to the ground from within 2.4 ft sq frames in each of the grazing exclusion cages and grazed plots. Clipped biomass will be weighed fresh, oven dried, and reweighed to determine dry mass weight. Dry mass weight per ring will be converted to kg/hectare and averaged for each camera trap. Unmanaged ungulate grazing pressure will be calculated as the average difference in forage biomass (kg/hectare) between the grazing exclusion cages and grazed plots for each camera trap (Bonham 2004). Changes in plant community composition across sampling periods will be evaluated for both grazed (no exclusion cage) and ungrazed (exclusion caged) plots using nested quadrats to derive key species frequencies (Bonham 2004), and dry-weight rank using clipped biomass (Bonham 2004).  Signs of unmanaged ungulate activity will also be recorded at each camera trapping location when cameras are deployed and recovered (Risch et al., 2020). Signs of ungulate activity have been proven to be effective measures of ungulate abundance and these data along with camera trapping data will be used to evaluate the relationship between unmanaged ungulate abundance and the resulting damages to producer lands.
3. Identify cultural significance of managed and unmanaged ungulates in agricultural landscapes of Hawai’i (Years 2-3). Cultural surveys and interviews. Integration of social values is critical to producer implementation (Gamborg et al. 2019), but these values may vary across stakeholders and wildlife species (Lohr et al. 2014). Semi-structured interviews will be conducted with a subset of cooperating ranchers, hunters, and fishers, and with Native Hawaiian cultural practitioners across the islands, in order to gain further insight and develop narrative. Interviews will be conducted via Zoom or in-person, following protocols as currently implemented on other cultural projects (Luat-Hūʻeu et al., under review, Sato et al. 2018). Interviewees will be selected using the snowball approach, adding interviewees until information saturation is reached within stakeholder groups. We will determine the connections between modern day values and culture, and past values and culture, enriching our understanding of the relationships between Hawaiian and local people and natural resources. Questions addressing attitudes and perceptions will include the following topics: unmanaged ungulate species that cause concern for agriculture, managed ungulate species [livestock], native species [e.g. plants, forest trees, birds, reptiles, fish], land and water resources [forests, streams, coastal ecosystems], hunting culture, fishing culture, paniolo culture, and other food-related cultural practices.  We will use this information to create culturally-sensitive IPMs (see objectives 4, 6). We will also engage with 4-H, FFA, and other youth regarding wildlife and culture through both web-based and in-person tools at community events and county fairs, and through youth interns placed by the Maui Economic Development Board. The interns will assist with development and promotion of a community science wildlife tracker website, as well as assisting in field data collection and public events such as youth fairs. 
4. Identify culturally appropriate and economically viable methods of control for unmanaged ungulates, in order to improve food security in Hawai’i (Years 2-3). Food security focus groups. Each island has unique agricultural producers, unique attitudes towards hunting, and different assemblages of invasive ungulates utilizing different portions of each island. Having identified types of damage through earlier economic and ecological survey work, we will create webinar and in-person focus group meetings with advisory teams of 5-10 people selected for each island, in order to address these differences. Ideas to be discussed would be type of hunting, type of hunting access, incentivization of hunting for ranch managers, perceived impacts on fish stocks, cost-share programs (Lituma & Buehler 2020) for ungulate fencing, wireless cattle collar fencing, meat inspection policy changes, and on-island meat processing/marketing. As an end goal we will use collected data to create culturally-informed IPM recommendations and geographically-explicit, multi-criteria decision support guidelines for producers and hunters (Objective 6). 
5. Educate stakeholders and policy decision-makers about the impacts of unmanaged ungulates on economics, agriculture, food security, and ecosystems in Hawai'i. This objective is detailed under the Education Plan.
6. Develop decision support guidelines that facilitate stakeholder choices for economically viable and culturally appropriate Integrated Pest Management Practices (IPM) for these ungulate populations, in order to mitigate damage to agricultural lands and ecosystems in the Hawaiian Islands (Years 2-3). Using information gained from Objectives 1-4, decision support guidelines will be created for producers to access IPM practices. The island-specific guidelines will allow producers and other stakeholders to choose best practices that help to identify: (a) ungulate challenges/solutions based on island (ungulate types vary by island), climate, crop, and soil type; (b) rotational grazing and stocking rates for livestock related to conservation values; and (c) incentives for hunting, exclusion, or other ungulate management, as a basis for both conservation and food security on the islands (Figure 3). 

Statistical analyses will be conducted using the program R (R Core Team. 2019). Resource selection functions (RSFs) will be used to estimate the use of the lands by wild ungulates (Boyce 2006). Multi-criteria Decision Analysis (MCDA) tools will be utilized to identify optimal solutions that account for social, cultural, ecological, and economic objectives.

Figure 2. System dynamics of ungulates, humans, and agricultural lands.

Figure 3. IPM Tool for developing decision support guidelines.