Feral cats are abundant in the Hawaiian Islands and pose a threat to native wildlife through predation and the spread of disease. A combination of factors including the submission of state bills and county resolutions has created the impression that a large segment of society supports the presence of feral cats in the islands and in-situ management techniques. The purpose of this research was to quantify the perceptions and desires of Hawai´i residents regarding the abundance and impact of feral cats. In 2011, I disseminated a social survey to approximately 5,000 Hawai´i residents including pre-identified wildlife stakeholders and a random sample of the general public. Data were analyzed using the potential for conflict index (PCI) and Wildlife Stakeholder Acceptance Capacity models. PCI results indicate that there is a high level of consensus within every stakeholder group that the abundance of feral cats should be decreased. Despite this result, 12% of respondents would like to see populations of feral cats persist in the islands. People’s desire to see the abundance of cats reduced was highly correlated (0.54) with whether or not people enjoyed seeing feral cats: 84% of survey respondents dislike seeing feral cats. We also asked survey recipients if feral cats should be removed permanently or relocated away from areas with threatened or endangered wildlife: the majority of people (78%) support the idea of permanently removing feral cats, whereas 10.1% would prefer to see feral cats relocated away from the specified area, and a small proportion of people (3%) believe that feral cats that are being fed do not kill other animals. This research reveals that a small segment of society supports the presence of feral cats, and that the majority of people would prefer to see feral cats removed from areas with threatened native fauna.

The effects of feral cats on Pacific island ecosystems are a well known and long standing pest problem. While control and/or eradication of feral cat populations have been successfully accomplished on several islands, they are typically in locations with little to no human population. The Hawaiian Islands have a human population of just over 1.2 million people, making certain feral cat control methods difficult, if not impossible, to implement. The University of Hawai`i at Mānoa, located in Honolulu, has a large number of feral cats living on it that often cause problems among the numerous stakeholders who use or frequent the campus. One of the primary concerns related to the cats is their feces, which may carry such diseases as toxoplasmosis and may cause illness in the employees that have to clean up after the cats. The university has implemented the use of feeding stations and litter boxes to obtain a population estimate and control the quantity of cat feces on the ground. But these two approaches have not been successful, due to inconsistent participation by the cat colony caretakers. Hence, little information exists about the status of the campus’s feral cat population. In order to begin addressing the campus cat problem, our goal is to develop a survey method for estimating the distribution and size of cat colonies, conduct health assessments, and identify ownership of cats with microchips. We are conducting surveys to estimate the population size, to see if it changes over time, and to determine basic health indices of the cats. Ultimately, we expect to provide information on whether the feral cat population is changing over time and whether or not trap-neuter-release efforts are succeeding and reducing the population relative to removal, and status quo management options.

Wildlife management and conservation biology are full of conflict, especially in regard to introduced vertebrates in Hawai`i. At present, there are 17 introduced mammals with established wild populations in Hawai`i, including 6 ruminants, 4 rodents, 3 feral pets, pigs, donkeys, rock wallabies, and mongooses. Disagreement about the reliability of information on the impacts of introduced mammals in Hawai`i is one reason for conflict between stakeholders, which may undermine conservation and management programs. The objective of this research was to assess what science has recorded in regards to the impact of introduced mammals on the native flora, fauna, and ecosystems of the Hawaiian Islands. A literature (peer-reviewed articles, theses, dissertations, and grey literature) search for data on the impact of these species resulted in 156 articles, which were assigned to 1 of 6 categories that describe science’s ‘Level of understanding’ of the impacts of mammals in Hawai`i. The vast majority of the available data (134/156 articles) resulted from basic observations or general exclosure plots. In terms of their impact in Hawai`i, cats (21 articles), black rats (27 articles), and pigs (40 articles) are the most researched and hence best understood species. Very little is known about the impacts of dogs, rabbits, brush-tailed rock wallabies, and donkeys on the flora, fauna, and ecosystems of Hawai`i. Analysis of the dates of publication of articles suggests research may be influenced by the level of controversy surrounding a species.

A large component of natural resources management is ultimately about understanding people. Such is the issue with feral cats, a species whose biology is well understood, but management can be contentious. Hawai‘i in particular is an important location in understanding the human dimensions side of feral cat management given the archipelago’s isolation, tropical climate, cultural history, and native biodiversity. Using both human dimensions and economic approaches, we sought to address the following questions: 1) Do stakeholders want to see changes in feral cat abundance? 2) What damages or benefits are correlated with stakeholder’s desired abundance of cats? 3) Which feral cat management techniques would stakeholders prefer to see employed? and, 4) Is it more cost effective to control feral cat abundance with trap-neuter-release (TNR) programs or trap and euthanize (TE) programs? To address our questions, we conducted both a statewide survey of 6 stakeholder groups across the state of Hawai‘i and developed a benefit-cost model coupled with a population model to evaluate TNR vs. TE. We found that across stakeholder groups a large majority of respondents would like to see a reduction in feral cats, and that support for different management options varied somewhat by stakeholder group. Overall, TNR was the least supported management option across stakeholder groups. Similarly, in a benefit-cost analysis, TNR was more expensive than TE across all range of scenarios. Our findings indicate that although there are differences amongst stakeholders in terms of attitudes and management preferences, that there is a strong consensus that the problem needs to be addressed.

Feral cats have flourished in urban areas of Hawai´i due to the state’s favorable climate and people’s positive perception of cats. However, the presence of large numbers of feral cats has raised concern both in terms of predation of native species and as vectors of disease. One disease, in particular, that has aroused a great deal of attention is toxoplasmosis, caused by the Toxoplasma gondii parasite. Cats are the definitive host of T. gondii and concerns arise regarding transmission to humans due to the relationships people have with cats. Another concern is the fact that the parasite has infected endemic and endangered species found in the state. Toxoplasma gondii oocysts are shed in cat excrement and can persist in soil between 1 and 4 years. The presence of T. gondii at cat colony sites could be an important factor when making decisions for the management of feral cats in the state. We intend to test soil samples taken from cat colony sites at the University of Hawai´i at Mânoa for T. gondii oocysts using molecular identification methods. Cat colony sites are defined by feeding stations maintained by cat colony caretakers. Given that cats are definitive hosts of T. gondii, we hypothesize that the presence of toxoplasmosis in soil is correlated to cat colony locations. Because most cats within a colony remain in close proximity to their feeding location, we predict that toxoplasmosis is spatially contained within tight proximity to cat colonies. If T. gondii oocysts are present in soil at the University of Hawai´i at Mânoa, then cat colonies may cause potential health hazards for landscaping personnel, students, staff, and visitors.

Nonnative feral ungulates have both direct and indirect impacts on native ecosystems. Hawai`i is particularly susceptible to biological invasions, as the islands have evolved in extreme geographic isolation. In this paper we explore the ecological impacts of nonnative feral goats (Capra hircus) in the Hawaiian Islands, including both the current state of knowledge and future research directions to address knowledge gaps. Understanding how invasive vertebrates impact island ecosystems is important as it provides an informed context for developing contemporary solutions to pressing management problems. Current knowledge gaps, such as the behavioral ecology of goats and their impacts on specific plant species and communities, limit the effectiveness of ecological restoration and conservation in Hawai`i. Emerging technologies in wildlife tracking and remote sensing will enable a greatly improved understanding of the behavior and ecological impacts of these nonnative animals in what is already a highly degraded ecosystem.

The introduction of rodents to islands poses a threat to native fauna, which often have no adaptation to defend their offspring or themselves from predation. To combat predation of nests and brooding females, the Kauai Forest Bird Recovery Project (KFBRP) has deployed 425 Goodnature A24 self-resetting rat traps at two field sites where high densities of native forest birds remain. One site is fenced to exclude invasive ungulates. KFBRP conducts routine trap checks every four months to assess bait and trap function and count carcasses. Typically, we find 0-3 rat or mouse carcasses at a trap, but in November 2018, we found a dead bird under a trap at the fenced site. We assume that traps kill more animals than indicated by carcass counts, because 75% of traps have counters that record when traps fire, and counter tallies exceed carcass counts. Thus, we hypothesize that some carcasses are scavenged or decompose between trap checks, and as a result we are a) underestimating target mortality with carcass counts and b) failing to detect non-target mortality. To test our hypotheses, we placed 30 non-native bird carcasses on transects in the fenced trapping grid in early December 2018. Carcasses were surveyed every at 10, 20, 45, 90, and 130 days after deployed. At the end of survey period, 19 (63%) carcasses could be easily detected, suggesting that we are detecting most carcasses after four months unless they are scavenged. Furthermore, our findings suggest that we would detect non-target mortality if it was prevalent.

Since human arrival to the Hawaiian Islands, non-native predators have decimated native flora and fauna. In particular, native forest bird populations have suffered due to rat (Rattus sp.) depredation. To protect native species, conservation practitioners have been removing rats and other rodents from ecologically sensitive areas. Identifying reliable strategies for assessing the effectiveness of these control efforts is critical, particularly given limited resources for conservation. A common method used for monitoring rodents is baited ink-plates within a tunnel (hereafter ink-plates). While this method is widely used, its effectiveness has yet to be evaluated in many ecosystems, including montane rainforests. To evaluate the effectiveness of monitoring rat presence with ink-plates, we focused on the Alakai Plateau on the island of Kauai, which is home to several of Hawaii’s most critically endangered birds, and where over 300 Goodnature™A24 rat traps are currently in operation. The Alakai experiences approximately 11 m of annual precipitation, giving rise to areas of dense vegetation, which may affect how rats encounter and interact with ink-plates. We paired 116 Reconyx™ HyperFire cameras with individual ink-plates inside tracking tunnels in the summers of 2022 and 2023, at a site with an ungulate exclusion fence and at a site with no fencing, to monitor areas both with and without rat traps. Rats were detected on approximately twice as many cameras (34.5% presence) compared to ink-plates (16.4% presence). These results suggest that cameras could be a powerful tool for accurately assessing the efficacy of conservation interventions to mitigate the impact of invasive predators on Hawaii’s native birds. Increased investments in camera technologies are worth consideration, particularly in the case of critically endangered species. Further research into the cost-effectiveness versus the information gained by the two methods could help further refine conservation strategies.

Online citizen science projects have broadened options for accessing science and enabled different forms of participation in scientific research for adult and young volunteers. Yet, little is known regarding participation patterns among youth participants. Quantitative approaches were used to investigate the contribution of 183 young volunteers to citizen science on the iNaturalist platform and the participation behaviour that relates to their contribution. The participants accessed and used iNaturalist as part of one-day field-based events (bioblitzes) facilitated by museums. Compared to the observation behaviour of all iNaturalist users, as documented on the platform, the young volunteers observe fewer plants and birds, and more molluscs, arachnids and insects. The average daily contributions of young volunteers were found to be positively associated with a large proportion of active days on iNaturalist and a systematic contribution behaviour, yet negatively related to a long duration on the platform. This study enhances our understanding of young volunteers' contributions to citizen science and provides insights for research on participation in online citizen science. Our findings have implications on how museums design the field-based events to encourage follow-up systematic participation and maintain active contribution.

This article was originally published electronically on the publisher's internet portal (currently SpringerLink) on April 3, 2019 without open access.