The perceived barriers to the use of assisted colonization identified by the 22 participants fell within nine categories (Table 1): economic constraints (21 participants), ecological risk and uncertainty (21 participants), lack of expertize (21 participants), institutional resistance (18 participants), policy and permitting (16 participants), lack of species data (16 participants), time commitments (6 participants), public perceptions (n = 6), and lack of capacity (n = 5). Below, we illustrate our findings with quotations from participants.
Economic constraints and funding uncertainty inhibited the consideration of assisted colonization. Some of the costs associated with assisted colonization were completing a translocation plan, obtaining permits, implementing the plan and conducting monitoring, captive propagation, animal husbandry, and habitat restoration. Economic constraints had the potential to mitigate the challenges posed by other barriers, as captured by P19: “We are not translocating things we need to because we don’t have the data and yet we don’t want to spend the money [to practice] our translocation techniques on [a species] that’s common. So probably we should have put some money into those common species. Funding is certainly a huge obstacle. Another huge obstacle is lack of knowledge. And another huge obstacle is permitting. Funding can help with all those things”.
Moving individuals from one island to another might reduce funding for the source island if the translocated population acted as an umbrella species that garners conservation funding that also benefits other conservation objectives. P5 explained, “if you remove a bird [species] from a particular island then the funding and focus may be taken from conservation efforts on that island”.
Substantial operating costs were associated with planning and implementing any type of translocation action. All participants noted that budgets were limited for any conservation management option and were not restricted to assisted colonization. P3 made the point that “conservation management is not supposed to take money or budget into consideration”. Similarly, P15 stated, “funding’s always going to be an issue no matter what you choose, especially conservation in Hawaiʻi”.
Two participants revealed that although funding is always a concern, assisted colonization could be less expensive than other conservation strategies for certain species. P21 commented, “[assisted colonization] would actually be cheaper in some instances because Oahu’s upper elevation habitats are really remote and hard to get to, whereas other islands have access points to remote areas that are [ideal] for constructing predator proof fencing…I would argue that in our situation, moving things to other islands to help recover them might actually be a cheaper option than having to fly materials and fly staff constantly to these really remote areas”.
Ecological Risk and Uncertainty
Participants recognized that models of the impacts of climate change exist for many species of concern in Hawaiʻi, such as forest birds and plants, but not for most invertebrates. Even for species for which impact models exist, we found that the inherent uncertainties in modeled projections, or even a lack of comfort with understanding complex models or ecology, may result in resistance to planning or acting on the basis of model outputs. P10 explained how this could differ depending on the species: “there are some [species] that are just inherently less risky to try [assisted colonization] with because you don’t have as much to lose if a bunch of them die as opposed to a species that is really slow breeding and has very complex social interactions”.
P20 shared an example of a concern about increases in ecological uncertainty when moving a species outside of its historical range: “If you’re moving a bird to part of its indigenous range where it just hasn’t been for 30 years, we aren’t concerned about that. But when you start talking about moving things like kiwikiu [Pseudonestor xanthophrys] to Big Island [Hawaiʻi Island], now you have a bird that has never been there. [It’s] a whole entire new ecosystem, so you don’t have any idea of how it’s going to interact”.
Other ecological uncertainties that were mentioned included potential risks to translocated individuals (e.g., direct mortality, genetic bottlenecks, inbreeding depression, hybridization) and potential risks and impacts to the recipient ecosystem (e.g., disease transmission, the potential for introduced species to become invasive). P18 highlighted one concern associated with disease transmission: “There would be other concerns such as ʻwhat if the reason [the translocated species] is not doing well in its native range… is due to some sort of heritable pathogen and then we move it. We don’t know much about the microbiome associated with insects or their pathogens in general… we are just kind of flying blind”.
Lack of Expertize
‘Lack of confidence’ and ‘unfamiliarity’ appeared to be barriers to the consideration of assisted colonization. P10 provided insight into how lack of experience may create a perceived barrier: “Ultimately everyone within conservation wants the same thing. They want the animals to get to where they can be safe successfully… Maybe it’s a difference in the level of confidence in the techniques. Just a lack of expertize or not feeling comfortable in doing it. I think just with any person, any manager, you want to stick to what you’re good at, and there’s not really a confidence in knowing how to do this yet”.
Twenty one participants noted that all other concerns regarding the use of assisted colonization, including some aspects of ecological risk and uncertainty, could be ameliorated through gaining experience with this management tool. P14 suggested, “[A local experienced agency] should create guidance on assisted colonization. That would alleviate some of the institutional resistance”. Fifteen participants expressed interest or support for increasing knowledge of assisted colonization by using less vulnerable species to set a precedent. P10 shared an example: “I am personally interested in the idea of assisted colonization of ʻamakihi (Loxops virens) [to Lanaʻi]. There was a subspecies [on Lanaʻi], they were extirpated, but there are some low elevation birds that are doing pretty well on other islands [such as ʻamakihi] that could be a potential source. For government agencies, these birds may not be a priority for them because they’re not super threatened, but it would be returning some functionality to a native ecosystem and also you might learn some techniques or tricks on something that isn’t as endangered before you have to try it on our critically endangered birds with 80 or 100 individuals left”.
Risk aversion by management authorities, or institutional resistance, was identified by 18 participants as hindering the consideration of assisted colonization. Resistance was associated with unfamiliarity with the strategy, unwillingness to implement high risk approaches, and fear of career repercussions. P19 disclosed, “people lose their jobs if a bird is killed, if an individual dies on their watch. So sometimes that’s the problem. No one loses their job over a species going extinct as far as I can tell, but people do lose their job over killing one bird, or they have consequences. So that’s really hard… That’s one thing that we need to look into is how we can protect people who take well considered and well informed risks to protect species”.
Emotional inhibition tied to negative past experiences also created resistance to the consideration of assisted colonization. P10 described the following experiences: “At a couple of meetings where, I wouldn’t call it knock-down-drag-out fights, but there were people in tears because of how strongly they disagreed with each other about whether assisted colonization was the only option left for the species…Failures [have] caused a fair amount of hesitancy within the conservation community. Some people are unwilling to try it, regardless of the amount of planning”.
Conflicting ideologies also influenced institutional resistance. P22 said, “I don’t think there’s a whole lot of funding available for something that is as new as [assisted colonization] and we’ve just gone through four years of denial that climate change is actually happening, so that kind of pushed us backward… in regard to funding, but also just general support for doing these types of things”.
Although assisted colonization has been viewed as controversial (Fazey and Fischer 2009; McLachlan et al. 2007; Ricciardi and Simberloff 2009), the alleviation of resistance was a central theme during interviews. Seven participants commented that in recent years, hesitation about assisted colonization has eased and perceptions have changed. Participants felt that these changes were associated with people becoming more comfortable with the strategy after years of discussion, the failure of traditional strategies, and as the increased risk of extinction. P19 commented, “I’ve definitely seen a change and I’ve been here 10 years. That culture is changing because [some managers] realized that their inaction, their unwillingness to accept risk, led to extinction”. Similarly, P20 said, “Everybody wants to conserve the species, nobody wants anything to go extinct. The disagreements all tend to be a different value of the risks and likelihood of success, of different tactics and different perceptions, different experiences. [Assisted Colonization] is not a silver bullet that’s going to solve the conservation issues. We are in desperate times for multiple species and multiple locations in Hawaiʻi, so all the options need to be considered. Everyone understands that”.
Policies and Permitting
Sixteen participants identified policy and permitting as barriers to the consideration of assisted colonization, recognizing that maneuvering through translocation policy and the permitting process can be restrictive and difficult. P21 shared, “I don’t think the policy is insurmountable, but I do think [assisted colonization] would be significantly harder and would require more consultation”. Participants observed that assisted colonization is a potential option under both federal and state law as it is allowed under the Endangered Species Act (ESA) under Section 10(j) and the experimental population provision (ESA, 16 U.S.C. 1539(j)(1)) and under Hawaiʻi Revised Statute (HRS) 195D-29 ‘release or establishment of endangered or threatened species outside its current range’ (HRS, 195D-29 L 1997, c 380, pt of §2) with approval from the state’s Endangered Species Recovery Committee. Seven participants noted the potential for misinterpretation of policy. P16 explained that although it may be legal, individual agreements could be prohibitive: “our cooperative agreement with the Fish and Wildlife Service, which hasn’t been revisited since the mid 1980s, explicitly states that we’re not allowed to… move endangered species outside of their known historical range. So technically we are still not allowed to do that and wouldn’t be unless that agreement changed”.
P12 highlighted the complexity of management by multiple jurisdictions: “If it was federal land and we wanted to collect a listed, endangered species then there is a whole other regulatory process, but the federal government doesn’t own much land in Hawaiʻi, so there’s not a federal nexus for them to infringe on these things for plants. But that would be different if you had an animal. Plants are considered part of the landscape and the animals are considered a federal jurisdiction. The Fish and Wildlife Service doesn’t assume responsibility for any plants on state property”.
Lack of Species Data
Sixteen participants raised concerns about gaps in knowledge of candidate species, particularly cryptic or rare species for which there may be little information on behavior or habitat, such as foraging, breeding habitat, and historical ranges. One participant noted that many invertebrates haven’t been described by science, and therefore understanding of their conservation status or management needs has not begun. P13 highlighted, “it is difficult to establish the historical range for species that are rare, cryptic, and are not present in the fossil record”. P19 shared an example regarding a Kauaʻi endemic forest bird, “One of our major barriers to translocating ʻakekeʻe [Loxops caeruleirostris] or doing anything with akekeʻe, even before a habitat suitability study, is that we actually know next to nothing about the species”.
Lack of species data was closely associated with ecological risks and uncertainties. P12 commented, “we have few years of experience with some species. Especially when species have one or few or no populations remaining [in the wild], it is hard to know preferred habitat requirements as what we see may not be optimal”. Similarly, P16 noted, “there’s a likelihood that where remaining endangered plants occur in the landscape over the last 60 years are not necessarily representative of where they were across the landscape as a whole. Those [historical] maps are a hypothesis of where those plants could have occurred…it could be misleading, and it may not be appropriate with climate change. They give us a picture of the niche of that species, but they could be in the worst possible habitat for that species, which is what I suspect for some [Hawaiian] plants”.
Six participants indicated that the length of time necessary to plan and implement assisted colonization is a barrier. Discussing previous management decisions for birds, P1 stated, “the option of assisted colonization was taken off the table early on, at least as an immediate option because it would not be immediate; assisted colonization is a detailed process”. Translocation is a long term commitment, and future funding is often uncertain. P18 shared an example: “So often, our grants are only two or three year grants, so by the time we have the funding to start working on something, we can’t afford the time to devote to that”.
P19 shared an example of a management decision from several years ago: “We didn’t really have any other strategy to look into because the time horizon for planning a translocation is lengthy and we wanted to do something that we could do more quickly because there’s so much more paperwork for a translocation… maybe we should have investigated translocation more seriously early on because if it works, it’s going have a bigger payoff, but it’s just super risky”.
The low population sizes of many Hawaiian species also relate to time constraints and may not be possible to overcome even with increased institutional support, data, or funding. P19 acknowledged that “slow but surely, we can chip away at gathering the ecological data. Slowly but surely, we are getting funding because people are concerned. But things move slowly and sometimes species don’t have time for us to move slowly. So that’s another problem”.
Negative public perceptions, or community resistance, were perceived as a barrier to the consideration of moving species outside of their historical range. This barrier was a greater consideration for well known, popular, or culturally important species. For example, P15 said, “[Some birds] certainly get a lot more spotlight. That means we might not be as willing to take risks as we might with, say, a plant or an invertebrate species. If [you] try a translocation and it fails, with a bird species there might be more public backlash than if that happened with another species group. So that is a concern”.
Interviews suggested community aversion to moving species from their native areas, and potential community resistance to receiving new species. P17 commented, “I think we’re very much aware of the need for community support. We need to justify why we’re spending the money that we do on conservation because it is taxpayer dollars a lot of the time. Also, to have coexistence, you need to have people be excited and accepting of species in their backyard. For [some species] that is not always the case”.
Community resistance was not perceived as a concern for all species. Rather, the lack of community support and knowledge of certain species impacted conservation support. P19 said, “[For] very iconic species that people instantly recognize, [the public] probably has more attachment to it. The little species I work on have been restricted to the darkest reaches of the island for so long, that very few residents care what they are. Unfortunately, people don’t even know our [species] and that’s actually a barrier to conservation”.
Lack of Capacity
Five participants identified lack of capacity as a barrier to the consideration and use of assisted colonization. Capacity concerns were associated with planning and implementation, data collection and dissemination, knowledge sharing, and policy and permitting. P9 shared an example where capacity was the greatest barrier to the use of assisted colonization for a particular species’ recovery plan: “we have a project where we want to move a species outside of its original range. It’s something that we probably should have done four years ago, and we still don’t even really have it started. For us…our obstacle is not having someone to do the planning work for it. We don’t have anyone who has the time… We haven’t even gotten to funding or anything like that yet, but it’s a lack of capacity”.
Lack of capacity was associated with a lack of data and limited dissemination of information that could increase expertize and mitigate ecological uncertainty. P12 shared several examples of implementing assisted colonization but lacking capacity to move beyond management and practice: “It’s really hard for me, as a manager, to have the time to publish. Maybe we don’t take enough robust data; we might monitor the [species] populations once a year, so we can’t determine specifically why exactly 10% died from slugs and 5% died from drought, or something like that. We don’t know those types of answers”. P7 noted that permitting constraints were also tied to limited capacity, saying, “more capacity is needed at [permitting agency] to expedite permits for threatened and endangered species”.