Towards reconciliation of the four world bird lists: hotspots of disagreement in taxonomy of raptors

Species Diagnosis and DNA Taxonomy

The use of DNA has helped to improve and speed up species identification and delimitation. However, it also provides new challenges to taxonomists. Incongruence of outcome from various markers and delimitation methods, bias from sampling and skewed species distribution, implemented models, and the choice of methods/priors may mislead results and also may, in conclusion, increase elements of subjectivity in species taxonomy. The lack of direct diagnostic outcome from most contemporary molecular delimitation approaches and the need for a reference to existing and best sampled trait reference systems reveal the need for refining the criteria of species diagnosis and diagnosability in the current framework of nomenclature codes and good practices to avoid nomenclatorial instability, parallel taxonomies, and consequently more and new taxonomic impediment.

Human impacts on the world’s raptors

Raptors are emblematic of the global biodiversity crisis because one out of five species are threatened with extinction and over half have declining populations due to human threats. Yet our understanding of where these “threats” impact raptor species is limited across terrestrial Earth. This is concerning because raptors, as apex predators, are critically positioned in ecological food webs, and their declining populations can undermine important ecosystem services ranging from pest control to disease regulation. Here, we map the distribution of 15 threats within the known ranges of 172 threatened and near threatened raptor species globally as declared by the International Union for the Conservation of Nature. We analyze the proportion of each raptor range that is exposed to threats, identify global hotspots of impacted raptor richness, and investigate how human impacts on raptors vary based on several intrinsic (species traits) and extrinsic factors. We find that humans are potentially negatively affecting at least one threatened raptor species across three quarters of Earth’s terrestrial area (78%; 113 million km2). Our results also show that raptors have 66% of their range potentially impacted by threats on average (range 2.7–100%). Alarmingly, critically endangered species have 90% of their range impacted by threats on average. We also highlight 57 species (33%) of particular concern that have > 90% of their ranges potentially impacted. Without immediate conservation intervention, these 57 species, including the most heavily impacted Forest Owlet (Athene blewitti), the Madagascar Serpent-eagle (Eutriorchis astur), and the Rufous Fishing-owl (Scotopelia ussheri), will likely face extinction in the near future. Global “hotspots” of impacted raptor richness are ubiquitous, with core areas of threat in parts of the Sahel and East Africa where 92% of the assessed raptors are potentially impacted per grid cell (10 species on average), and in Northern India where nearly 100% of raptors are potentially impacted per grid cell (11 species). Additionally, “coolspots” of unimpacted richness that represent refuges from threats occur in Greenland and Canada, where 98 and 58% of raptors are potentially unimpacted per grid cell, respectively (nearly one species on average), Saharan Africa, where 21% of raptors are potentially unimpacted per grid cell (one species on average), and parts of the Amazon, where 12% of raptors are potentially unimpacted per grid cell (0.6 species on average). The results provide essential information to guide conservation planning and action for the world’s imperiled raptors.

Raptor research during the COVID-19 pandemic provides invaluable opportunities for conservation biology

Research is underway to examine how a wide range of animal species have responded to reduced levels of human activity during the COVID-19 pandemic. In this perspective article, we argue that raptors (i.e., the orders Accipitriformes, Cariamiformes, Cathartiformes, Falconiformes, and Strigiformes) are particularly well-suited for investigating potential 'anthropause' effects: they are sensitive to environmental perturbation, affected by various human activities, and include many locally and globally threatened species. Lockdowns likely alter extrinsic factors that normally limit raptor populations. These environmental changes are in turn expected to influence - mediated by behavioral and physiological responses - the intrinsic (demographic) factors that ultimately determine raptor population levels and distributions. Using this population-limitation framework, we identify a range of research opportunities and conservation challenges that have arisen during the pandemic, related to changes in human disturbance, light and noise pollution, collision risk, road-kill availability, supplementary feeding, and persecution levels. Importantly, raptors attract intense research interest, with many professional and amateur researchers running long-term monitoring programs, often incorporating community-science components, advanced tracking technology and field-methodological approaches that allow flexible timing, enabling continued data collection before, during, and after COVID-19 lockdowns. To facilitate and coordinate global collaboration, we are hereby launching the 'Global Anthropause Raptor Research Network' (GARRN). We invite the international raptor research community to join this inclusive and diverse group, to tackle ambitious analyses across geographic regions, ecosystems, species, and gradients of lockdown perturbation. Under the most tragic of circumstances, the COVID-19 anthropause has afforded an invaluable opportunity to significantly boost global raptor conservation.

Relative Conservation Status of Bird Orders With Special Attention to Raptors

Birds, especially raptors, play important roles in ecosystems. We examine the International Union for the Conservation of Nature’s (IUCN) Red List to determine which orders of birds have proportionally more or fewer species listed as threatened or declining compared to the Class-wide average. We further examine whether raptors are more threatened or declining than non-raptors and whether the order Accipitriformes is particularly threatened even when excluding Old World vultures – which are especially imperiled. Our results reveal heterogeneity across bird orders in proportions of threatened and declining species, with some orders having greater or lower proportions than the Class-wide proportion. We also show that the proportions of threatened species in each order are correlated with the proportion of declining species. Raptors have both greater proportions of threatened and declining species than non-raptors and Accipitriformes has greater-than-average proportions of threatened and declining species, even if Old World vultures are removed from the analysis. Our results should serve as a framework for discussion of the relative conservation status of bird orders, especially raptors, which are in need of increased conservation attention.