Climate Change, Modelling and Conservation of the World’s Terrestrial birds

Global climate change is an important threat to biodiversity and is predicted to be a major driver of wildlife population extinctions throughout the current century. Across a wide range of taxa, a well-documented response to climate change has been changes in species distributions, often towards higher latitudes and altitudes. Species distribution models (SDMs) have been widely used to predict further range changes in future but their use has often focused on discrete geographical areas. Moreover, SDMs have typically been correlative, ignoring biological traits. Here, I use SDMs to project future ranges for the world’s terrestrial birds under climate change. To improve the realism of projected range changes, I incorporate biological traits, including species’ age at first breeding and natal dispersal range. I use these projections to predict large-scale patterns in the responses of terrestrial birds to climate change, and to explore the implications of these models for avian conservation. There is little consensus on the most useful predictors for SDMs, so I begin by exploring how this varies geographically. With this knowledge, I develop SDMs for the world’s terrestrial birds and project future species ranges using three different global climate models (CCSM4, GFDL-CM3, HadGEM2-ES) under a low (rcp26), a medium (rcp45) and a high (rcp85) representative concentration pathway. The projected ranges are used to identify species most at risk from climate change and to highlight global hotspots where species are projected to experience the highest range losses. I explore how the projected range changes affect global species communities and I identify areas where species communities are projected to change or novel communities will emerge. I assess how projected changes will affect the ability of the global Important Bird and Biodiversity Areas (IBAs) network to confer protection on the world’s terrestrial bird species. Additionally, I highlight - based on projected range loss and suitable habitat and climate space beyond the dispersal range - species that will be unable to track climate change and that could be candidates for Assisted Colonization (AC). Finally, I explore the divergence between global species richness (SR) patterns and phylogenetic diversity (PD) for the world’s terrestrial birds, to assess if measuring biodiversity and setting conservation targets based on SR can be expected to cover their PD as well. Identifying the global consequences of projected range changes can inform future conservation efforts and research priorities. Changes in range extent and overlap were projected for the vast majority of the world’s terrestrial birds, with one-fifth projected to experience major range losses (>75% decline in range extent projected). This has far reaching consequences for the IBA network, with an overall trend of species moving out of the IBA coverage. Furthermore 13% of the world’s terrestrial birds are projected to have severe range losses that, combined with an inability to follow suitable habitat and climate space, mean they could benefit from AC as a conservation tool. Overall, PD was found to be highly correlated to SR on a global scale; however, there are localized differences where PD is higher or lower than could be expected from SR alone. These differences suggest that considering PD could enhance conservation planning. The results demonstrate the major threat that climate change poses for the world’s terrestrial bird species across all areas of the globe, and highlight the importance of considering climate change impacts to enhance their protection

Utilizing multi-objective decision support tools for protected area selection

Establishing and maintaining protected areas (PAs) is a key action in delivering post-2020 biodiversity targets. PAs often need to meet multiple objectives, ranging from biodiversity protection to ecosystem service provision and climate change mitigation, but available land and conservation funding is limited. Therefore, optimizing resources by selecting the most beneficial PAs is vital. Here, we advocate for a flexible and transparent approach to selecting PAs based on multiple objectives, and illustrate this with a decision support tool on a global scale. The tool allows weighting and prioritization of different conservation objectives according to user-specified preferences as well as real-time comparison of the outcome. Applying the tool across 1,346 terrestrial PAs, we demonstrate that decision makers frequently face trade-offs among conflicting objectives, e.g., between species protection and ecosystem integrity. Nevertheless, we show that transparent decision support tools can reveal synergies and trade-offs associated with PA selection, thereby helping to illuminate and resolve land-use conflicts embedded in divergent societal and political demands and values.publishedVersio

Site-Based Conservation of Terrestrial Bird Species in the Caribbean and Central and South America Under Climate Change

Two of the principal responses of species to recent climate change have been changes in range and abundance, leading to a global reshuffling of the geographic distribution of species. Such range changes may cause species to disappear from areas they currently occupy and, given the right conditions, to colonize new sites. This could affect the ability of site networks (such as protected areas) to conserve species. Identifying sites that will continue to provide suitable conditions for focal species under future climate change scenarios and sites that are likely to become unsuitable is important for effective conservation planning. Here we explore the impacts of climate change on terrestrial bird species of conservation concern in the Neotropics, and the consequences for the network of Important Bird and Biodiversity Areas (IBAs) identified to conserve them. We modelled changes in species distributions for 3,798 species across the Caribbean and Central and South America, accounting for species-specific biological traits (natal dispersal ability and generation length), to assess species occurrences within IBAs under different future climate scenarios. Based on the projected changes in species compositions, we identified potential management strategies for the individual sites of the network. We projected that future climate change will have substantial impacts on the distribution of individual species across the IBA network, resulting in very heterogenous impacts on the individual IBAs. Mean turnover of species of conservation concern within IBAs was 17% by 2050. Nonetheless, under a medium-warming scenario, for 73% of the 939 species of conservation concern, more than half of the IBAs in which they currently occur were projected to remain climatically suitable, and for 90% at least a quarter of the sites remain suitable. These results suggest that the IBA network will remain robust under climate change. Nevertheless, 7% of the species of conservation concern are projected to have no suitable climate in the IBAs currently identified for them. Our results highlight the importance of a network-wide perspective when taking management decisions for individual sites under climate change

Climate change impacts on the phylogenetic diversity of the world’s terrestrial birds: more than species numbers

Ongoing climate change is a major threat to biodiversity and impacts on species distributions and abundances are already evident. Heterogenous responses of species due to varying abiotic tolerances and dispersal abilities have the potential to further amplify or ameliorate these impacts through changes in species assemblages. Here we investigate the impacts of climate change on terrestrial bird distributions and, subsequently, on species richness as well as on different aspects of phylogenetic diversity of species assemblages across the globe. We go beyond previous work by disentangling the potential impacts on assemblage phylogenetic diversity of species gains vs. losses under climate change and compare the projected impacts to randomized assemblage changes. We show that climate change might not only affect species numbers and composition of global species assemblages but could also have profound impacts on assemblage phylogenetic diversity, which, across extensive areas, differ significantly from random changes. Both the projected impacts on phylogenetic diversity and on phylogenetic structure vary greatly across the globe. Projected increases in the evolutionary history contained within species assemblages, associated with either increasing phylogenetic diversification or clustering, are most frequent at high northern latitudes. By contrast, projected declines in evolutionary history, associated with increasing phylogenetic over-dispersion or homogenisation, are projected across all continents. The projected widespread changes in the phylogenetic structure of species assemblages show that changes in species richness do not fully reflect the potential threat from climate change to ecosystems. Our results indicate that the most severe changes to the phylogenetic diversity and structure of species assemblages are likely to be caused by species range shifts rather than range reductions and extinctions. Our findings highlight the importance of considering diverse measures in climate impact assessments and the value of integrating species-specific responses into assessments of entire community changes

Projected climate change impacts on the phylogenetic diversity of the world's terrestrial birds: more than species numbers

Ongoing climate change is a major threat to biodiversity. As abiotic tolerances and dispersal abilities vary, species-specific responses have the potential to further amplify or ameliorate the ensuing impacts on species assemblages. Here, we investigate the effects of climate change on species distributions across non-marine birds, quantifying its projected impact on species richness (SR) as well as on different aspects of phylogenetic diversity globally. Going beyond previous work, we disentangle the potential impacts of species gains versus losses on assemblage-level phylogenetic diversity under climate change and compare the projected impacts to randomized assemblage changes. We show that beyond its effects on SR, climate change could have profound impacts on assemblage-level phylogenetic diversity and composition, which differ significantly from random changes and among regions. Though marked species losses are most frequent in tropical and subtropical areas in our projections, phylogenetic restructuring of species communities is likely to occur all across the globe. Furthermore, our results indicate that the most severe changes to the phylogenetic diversity of local assemblages are likely to be caused by species range shifts and local species gains rather than range reductions and extinctions. Our findings highlight the importance of considering diverse measures in climate impact assessments

Bioenergy cropland expansion may offset positive effects of climate change mitigation for global vertebrate diversity

Climate and land-use change interactively affect biodiversity. Large-scale expansions of bioenergy have been suggested as an important component for climate change mitigation. Here we use harmonized climate and land-use projections to investigate their potential combined impacts on global vertebrate diversity under a low- and a high-level emission scenario. We combine climate-based species distribution models for the world’s amphibians, birds, and mammals with land-use change simulations and identify areas threatened by both climate and land-use change in the future. The combined projected effects of climate and land-use change on vertebrate diversity are similar under the two scenarios, with land-use change effects being stronger under the low- and climate change effects under the high-emission scenario. Under the low-emission scenario, increases in bioenergy cropland may cause severe impacts in biodiversity that are not compensated by lower climate change impacts. Under this low-emission scenario, larger proportions of species distributions and a higher number of small-range species may become impacted by the combination of land-use and climate change than under the high-emission scenario, largely a result of bioenergy cropland expansion. Our findings highlight the need to carefully consider both climate and land-use change when projecting biodiversity impacts. We show that biodiversity is likely to suffer severely if bioenergy cropland expansion remains a major component of climate change mitigation strategies. Our study calls for an immediate and significant reduction in energy consumption for the benefit of both biodiversity and to achieve the goals of the Paris Agreement

Global impacts of climate change on avian functional diversity

Climate change is predicted to drive geographical range shifts, leading to fluctuations in species richness (SR) worldwide. However, the effect of these changes on functional diversity (FD) remains unclear, in part because comprehensive species-level trait data are generally lacking at global scales. Here, we use morphometric and ecological traits for 8268 bird species to estimate the impact of climate change on avian FD. We show that future bird assemblages are likely to undergo substantial shifts in trait structure, with a magnitude of change greater than predicted from SR alone, and a direction of change varying according to geographical location and trophic guild. For example, our models predict that FD of insect predators will increase at higher latitudes with concurrent losses at mid-latitudes, whereas FD of seed dispersing birds will fluctuate across the tropics. Our findings highlight the potential for climate change to drive continental-scale shifts in avian FD with implications for ecosystem function and resilience

How to resolve conflicting conservation objectives: A decision support tool for the global selection of multi-purpose protected areas

The establishment and maintenance of protected areas(PAs) is viewed as a key action in delivering post-2020 biodiversity targets. PAs often need to meet a multitude of objectives, ranging from biodiversity protection to ecosystem service provision and climate change mitigation. As available land and conservation funding are limited, optimizing resources by selecting the most beneficial PAs is vital. Here we present a decision support tool that enables a flexible approach to PA selection on a global scale, allowing different conservation objectives to be weighted and prioritized according to user-specified preferences. We apply the tool across 1347 terrestrial PAs and highlight frequent trade-offs among different objectives, e.g., between biodiversity protection and ecosystem integrity. These results indicate that decision makers must usually decide among conflicting objectives. To assist this our decision support tool provides an explicitly value-based approach that can help resolve such conflicts by considering divergent societal and political demands and values