EDITOR'S CHOICE: Saving the hihi under climate change: a case for assisted colonization

Novel Conditions in Conservation Translocations: A Conservative-Extrapolative Strategic Framework

In response to anthropogenic threats, conservation translocations are increasingly used to combat species' population and range declines. However, moving animals outside of their current distribution can mean introducing them to novel conditions, even in the case of reintroductions to formerly inhabited areas due to ecosystem changes following extirpation. This exposure to novel conditions introduces uncertainty that can undermine decision making for species conservation. Here we propose two strategies, which we define as conservative and extrapolative, for approaching and managing novelty and the resulting uncertainty in conservation translocations. Conservative strategies are characterised by the avoidance and removal of novel conditions as much as possible, whereas extrapolative strategies are more experimental, allowing exposure to novel conditions and monitoring outcomes to increase understanding of a species' ecology. As each strategy carries specific risks and opportunities, they will be applicable in different scenarios. Extrapolative strategies suit species in recovery which can afford some experimental management, or species facing novel and emerging threats which require less traditional translocations, such as assisted colonisations. We provide examples, applying our framework to two endemic New Zealand species with long histories of translocation management: tuatara (Sphenodon punctatus), a reptile and takahē (Porphyrio hochstetteri), a flightless bird.

Importance of species translocations under rapid climate change

Species that cannot adapt or keep pace with a changing climate are likely to need human intervention to shift to more suitable climates. While hundreds of articles mention using translocation as a climate-change adaptation tool, in practice, assisted migration as a conservation action remains rare, especially for animals. This is likely due to concern over introducing species to places where they may become invasive. However, there are other barriers to consider, such as time-frame mismatch, sociopolitical, knowledge and uncertainty barriers to conservationists adopting assisted migration as a go-to strategy. We recommend the following to advance assisted migration as a conservation tool: attempt assisted migrations at small scales, translocate species with little invasion risk, adopt robust monitoring protocols that trigger an active response, and promote political and public support.

Back home? Uncertainties for returning seized animals to the source-areas under climate change

Regardless of the economic, social and environmental impacts caused by wild animal trafficking worldwide, the suitable destination of seized specimens is one of the main challenges faced by environmental managers and authorities. In Brazil, returning seized animals to the wild has been the most frequent path in population restoration programs, and has been carried out, as a priority, in areas where the animals were captured. However, in addition to the difficulty in identifying the locations of illegal captures, little scientific knowledge is available on the future viability of the source-areas to global climate change. Thus, the current work aims to evaluate the impacts of climate change on the main source-municipalities for animal trafficking in Brazil, referred to herein as source-areas. For this, using ecological niche modeling, the environmental suitability of the source-areas for illegal animal captures was evaluated in two scenarios at two different time horizons: optimistic (RCP 26) and pessimistic (RCP 85) emission scenarios in both 2050 and 2070 projections. Moreover, the source-areas were compared with the Brazilian Federal protected areas, used here as the control group. According to the results, Brazilian source-municipalities are not always the best option for maintaining the most seized species in the future simulations, and, therefore, seem not be the best option for projects that aim for the return of these animals to the wild. In this sense, despite the genetic and ecological issues inherent in translocation projects, our results suggest that population restoration programs for seized species need to be rethought, and furthermore other suitable areas could be considered for truly ensuring the survival and maintenance of overexploited populations in the long term.

Can threatened species adapt in a restored habitat? No expected evolutionary response in lay date for the New Zealand hihi

Many bird species have been observed shifting their laying date to earlier in the year in response to climate change. However, the vast majority of these studies were performed on non-threatened species, less impacted by reduced genetic diversity (which is expected to limit evolutionary response) as a consequence of genetic bottlenecks, drift and population isolation. Here, we study the relationship between lay date and fitness, as well as its genetic basis, to understand the evolutionary constraints on phenology faced by threatened species using a recently reintroduced population of the endangered New Zealand passerine, the hihi (Notiomystis cincta). A large discrepancy between the optimal laying date and the mode of laying date creates a strong selection differential of -11.24. The impact of this discrepancy on fitness is principally mediated through survival of offspring from hatchling to fledgling. This discrepancy does not seem to arise from a difference in female quality or a trade-off with lifetime breeding success. We find that start of breeding season depends on female age and average temperature prior to the breeding season. Laying date is not found to be significantly heritable. Overall, our research suggests that this discrepancy is a burden on hihi fitness, which will not be resolved through evolution or phenotypic plasticity. More generally, these results show that threatened species introduced to restored habitats might lack adaptive potential and plasticity to adjust their phenology to their new environment. This constraint is also likely to limit their ability to face future challenges, including climate change.

Reflections on a seminal paper in conservation biology: the legacy of Peters and Darling (1985)

‘The Greenhouse Effect and Nature Reserves’ by Robert Peters and Joan Darling, published in the journal Bioscience more than 30 years ago, was a ground-breaking synthesis. Drawing on paleoecology, community ecology and biogeography, the review laid out many concepts about species vulnerability to climate change that have become central tenets of research on climate change adaptation in natural ecosystems. Remarkably, the paper also provided a clear and logical framework for flexible, forward-thinking and interventionist management action, including recommendations about the design of protected areas, and the need for species translocation to reduce extinction risk. Reflecting on the legacy of this paper, it is clear that the uptake of such approaches over the intervening decades has been extremely slow, representing many lost opportunities to reduce species vulnerability to rapid environmental change. This paper is a tribute to the prescience of Peters and Darling, and a call to revisit their farsighted advice to meet conservation challenges that continue to accelerate.

Assessing the potential of translocating vulnerable forest birds by searching for novel and enduring climatic ranges

Hawaiian forest birds are imperiled, with fewer than half the original >40 species remaining extant. Recent studies document ongoing rapid population decline and project complete climate-based range losses for the critically endangered Kaua'i endemics 'akeke'e (Loxops caeruleirostris) and 'akikiki (Oreomystis bairdi) by end-of-century due to projected warming. Climate change facilitates the upward expansion of avian malaria into native high elevation forests where disease was historically absent. While intensified conservation efforts attempt to safeguard these species and their habitats, the magnitude of potential loss and the urgency of this situation require all conservation options to be seriously considered. One option for Kaua'i endemics is translocation to islands with higher elevation habitats. We explored the feasibility of interisland translocation by projecting baseline and future climate-based ranges of 'akeke'e and 'akikiki across the Hawaiian archipelago. For islands where compatible climates for these species were projected to endure through end-of-century, an additional climatic niche overlap analysis compares the spatial overlap between Kaua'i endemics and current native species on prospective destination islands. Suitable climate-based ranges exist on Maui and Hawai'i for these Kaua'i endemics that offer climatically distinct areas compared to niche distributions of destination island endemics. While we recognize that any decision to translocate birds will include assessing numerous additional social, political, and biological factors, our focus on locations of enduring and ecologically compatible climate-based ranges represents the first step to evaluate this potential conservation option. Our approach considering baseline and future distributions of species with climatic niche overlap metrics to identify undesirable range overlap provides a method that can be utilized for other climate-vulnerable species with disjointed compatible environments beyond their native range.

Determinants of male floating behaviour and floater reproduction in a threatened population of the hihi (Notiomystis cincta)

Floating males are usually thought of as nonbreeders. However, some floating individuals are able to reproduce through extra-pair copulations. Floater reproductive success can impact breeders' sex ratio, reproductive variance, multiple paternity and inbreeding, particularly in small populations. Changes in reproductive variance alter the rate of genetic drift and loss of genetic diversity. Therefore, genetic management of threatened species requires an understanding of floater reproduction and determinants of floating behaviour to effectively conserve species. Here, we used a pedigreed, free-living population of the endangered New Zealand hihi (Notiomystis cincta) to assess variance in male reproductive success and test the genetic (inbreeding and heritability) and conditional (age and size) factors that influence floater behaviour and reproduction. Floater reproduction is common in this species. However, floater individuals have lower reproductive success and variance in reproductive success than territorial males (total and extra-pair fledglings), so their relative impact on the population's reproductive performance is low. Whether an individual becomes a floater, and if so then how successful they are, is determined mainly by individual age (young and old) and to lesser extents male size (small) and inbreeding level (inbred). Floating males have a small, but important role in population reproduction and persistence of threatened populations.

Reversing defaunation: restoring species in a changing world

The rate of biodiversity loss is not slowing despite global commitments, and the depletion of animal species can reduce the stability of ecological communities. Despite this continued loss, some substantial progress in reversing defaunation is being achieved through the intentional movement of animals to restore populations. We review the full spectrum of conservation translocations, from reinforcement and reintroduction to controversial conservation introductions that seek to restore populations outside their indigenous range or to introduce ecological replacements for extinct forms. We place the popular, but misunderstood, concept of rewilding within this framework and consider the future role of new technical developments such as de-extinction.