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The population extinction pulse we describe here shows, from a quantitative viewpoint, that Earth’s sixth mass extinction is more severe than perceived when looking exclusively at species extinctions. Therefore, humanity needs to address anthropogenic population extirpation and decimation immediately. That conclusion is based on analyses of the numbers and degrees of range contraction (indicative of population shrinkage and/or population extinctions according to the International Union for Conservation of Nature) using a sample of 27,600 vertebrate species, and on a more detailed analysis documenting the population extinctions between 1900 and 2015 in 177 mammal species. We find that the rate of population loss in terrestrial vertebrates is extremely high—even in “species of low concern.” In our sample, comprising nearly half of known vertebrate species, 32% (8,851/27,600) are decreasing; that is, they have decreased in population size and range. In the 177 mammals for which we have detailed data, all have lost 30% or more of their geographic ranges and more than 40% of the species have experienced severe population declines (>80% range shrinkage). Our data indicate that beyond global species extinctions Earth is experiencing a huge episode of population declines and extirpations, which will have negative cascading consequences on ecosystem functioning and services vital to sustaining civilization. We describe this as a “biological annihilation” to highlight the current magnitude of Earth’s ongoing sixth major extinction event.

Severe insect declines make headlines, but they are rarely based on systematic monitoring outside of Europe. We estimate the rate of change in total butterfly abundance and the population trends for 81 species using 21 years of systematic monitoring in Ohio, USA. Total abundance is declining at 2% per year, resulting in a cumulative 33% reduction in butterfly abundance. Three times as many species have negative population trends compared to positive trends. The rate of total decline and the proportion of species in decline mirror those documented in three comparable long-term European monitoring programs. Multiple environmental changes such as climate change, habitat degradation, and agricultural practices may contribute to these declines in Ohio and shift the makeup of the butterfly community by benefiting some species over others. Our analysis of life-history traits associated with population trends shows an impact of climate change, as species with northern distributions and fewer annual generations declined more rapidly. However, even common and invasive species associated with human-dominated landscapes are declining, suggesting widespread environmental causes for these trends. Declines in common species, although they may not be close to extinction, will have an outsized impact on the ecosystem services provided by insects. These results from the most extensive, systematic insect monitoring program in North America demonstrate an ongoing defaunation in butterflies that on an annual scale might be imperceptible, but cumulatively has reduced butterfly numbers by a third over 20 years.

Long-term studies on the population dynamics of tropical resident birds are few, and it remains poorly understood how their populations have fared in recent decades. Here, we analyzed a 44-y population study of a Neotropical understory bird assemblage from a protected forest reserve in central Panama to determine if and how populations have changed from 1977 to 2020. Using the number of birds captured in mist nets as an index of local abundance, we estimated trends over time for a diverse suite of 57 resident species that comprised a broad range of ecological and behavioral traits. Estimated abundances of 40 (∼70%) species declined over the sampling period, whereas only 2 increased. Furthermore, declines were severe: 35 of the 40 declining species exhibited large proportional losses in estimated abundance, amounting to ≥50% of their initial estimated abundances. Declines were largely independent of ecology (i.e., body mass, foraging guild, or initial abundance) or phylogenetic affiliation. These widespread, severe declines are particularly alarming, given that they occurred in a relatively large (∼22,000-ha) forested area in the absence of local fragmentation or recent land-use change. Our findings provide robust evidence of tropical bird declines in intact forests and bolster a large body of literature from temperate regions suggesting that bird populations may be declining at a global scale. Identifying the ecological mechanisms underlying these declines should be an urgent conservation priority.

Illegal hunting is a persistent problem in many protected areas, but an overview of the extent of this problem and its impact on wildlife is lacking. We reviewed 40 years (1980-2020) of global research to examine the spatial distribution of research and socio-ecological factors influencing population decline within protected areas under illegal hunting pressure. From 81 papers reporting 988 species/site combinations, 294 mammal species were reported to have been illegally hunted from 155 protected areas across 48 countries. Research in illegal hunting has increased substantially during the review period and showed biases towards strictly protected areas and the African continent. Population declines were most frequent in countries with a low human development index, particularly in strict protected areas and for species with a body mass over 100 kg. Our results provide evidence that illegal hunting is most likely to cause declines of large-bodied species in protected areas of resource-poor countries regardless of protected area conservation status. Given the growing pressures of illegal hunting, increased investments in people's development and additional conservation efforts such as improving anti-poaching strategies and conservation resources in terms of improving funding and personnel directed at this problem are a growing priority.

1. Estimating how much long-distance migrant populations spread out and mix during the non-breeding season (migratory connectivity) is essential for understanding and predicting population dynamics in the face of global change. 2. We quantify variation in population spread and inter-population mixing in long-distance, terrestrial migrant land-bird populations (712 individuals from 98 populations of 45 species, from tagging studies in the Neotropic and Afro-Palearctic flyways). We evaluate the Mantel test as a metric of migratory connectivity, and explore the extent to which variance in population spread can be explained simply by geography. 3. The mean distance between two individuals from the same population during the nonbreeding season was 743 km, covering 10-20% of the maximum width of Africa/South America. Individuals from different breeding populations tended to mix during the non-breeding season, although spatial segregation was maintained in species with relatively large non-breeding ranges (and, to a lesser extent, those with low population-level spread). A substantial amount of between-population variation in population spread was predicted simply by geography, with populations using non-breeding zones with limited land availability (e.g. Central America compared to South America) showing lower population spread. 4. The high levels of population spread suggest that deterministic migration tactics are not generally adaptive; this makes sense in the context of the recent evolution of the systems, and the spatial and temporal unpredictability of non-breeding habitat. 5. The conservation implications of generally low connectivity are that the loss (or protection) of any non-breeding site will have a diffuse but widespread effect on many breeding populations. Although low connectivity should engender population resilience to shifts in habitat (e.g. due to climate change), we suggest it may increase susceptibility to habitat loss. We hypothesize that, because a migrant species cannot adapt to both simultaneously, migrants generally may be more susceptible to population declines in the face of concurrent anthropogenic habitat and climate change.

Vultures provide critical ecosystem services, yet populations of many species have collapsed worldwide. We present the first estimates of a 30‐year Pan‐African vulture decline, confirming that declines have occurred on a scale broadly comparable with those seen in Asia, where the ecological, economic, and human costs are already documented. Populations of eight species we assessed had declined by an average of 62%; seven had declined at a rate of 80% or more over three generations. Of these, at least six appear to qualify for uplisting to Critically Endangered. Africa's vultures are facing a range of specific threats, the most significant of which are poisoning and trade in traditional medicines, which together accounted for 90% of reported deaths. We recommend that national governments urgently enact and enforce legislation to strictly regulate the sale and use of pesticides and poisons, to eliminate the illegal trade in vulture body parts, as food or medicine, and to minimize mortality caused by power lines and wind turbines.

Background The garden dormouse ( Eliomys quercinus ) is one of the fastest-declining mammals in Europe, and action is needed to prevent further population losses. The primary causes of declines are not well-understood, as the species experiences variable conditions and threats across its range, but likely include habitat fragmentation and loss. Previous genetic studies have provided evidence of highly structured garden dormouse populations in Western Europe, despite this region having been defined as a single clade with mitochondrial DNA analysis. Within Western Europe, the magnitude of declines has been recognized to be greater on the eastern edge of the species’ range, which could explain differentiation within the clade as resulting from diversity loss and genetic drift for regions under greater risk of extirpation. Here, we focus on fine-scale genomic differentiation across the Western European clade to explore the consequences of genomic erosion on the eastern region and to help identify mechanisms driving genetic differentiation within this species. Results We found genetic differentiation both between and within major geographic regions. Populations located in the eastern edge of the species’ range showed stronger signs of population isolation, including structure between spatially distant populations, lower genetic diversity, and greater rates of inbreeding. However, all populations exhibited signals of recent rapid population decline. Outlier analyses indicated that differentiation between regions was primarily due to genetic drift resulting from isolation-by-distance rather than adaptive differentiation. We also found genetic structuring between populations within the Rhine Valley, despite apparent lack of physical barriers preventing dispersal among groups within this region. Conclusions Our findings indicate that population isolation following habitat loss and fragmentation has likely been a major contributor to garden dormouse declines. Dispersal among disparate garden dormouse sampling regions is restricted—even across local spatial scales—leading to loss of genetic diversity and potential erosion of evolutionary potential. With 21st century declines expected to continue across the species’ range, even relatively common and well-connected populations are likely to follow the trajectory of the eastern populations, with increasing loss of diversity as populations contract and become more isolated.

Depopulation constitutes a fundamental challenge for territorial governance, particularly within the framework of sustainable development; however, its representation in local strategic documents remains insufficiently explored. This study aims to identify and compare strategic responses to depopulation across two contrasting Polish regions—Dolnośląskie Voivodeship and Podlaskie Voivodeship—and three governance levels: regional, county, and municipal. An abductive mixed-methods approach was applied, combining discourse analysis with latent semantic analysis (LDA), and principal component analysis (PCA). The findings reveal a clear dominance of the pro-growth paradigm, while the adaptive approach associated with managed shrinkage remains marginal. Regional differences are primarily observed in problem framing—functional in Dolnośląskie and demographic in Podlaskie—but these distinctions do not significantly affect the types of policy responses. Structural instruments, particularly those related to consolidation, prevail, whereas functional and competency-based measures are less prominent. The results suggest the existence of a standardized model of strategic response to depopulation across regions and governance levels. This indicates limited diversification of policy approaches and highlights the need to more fully integrate adaptive strategies into territorial policy, especially in the context of long-term demographic change.

Background Anthropogenic forces have resulted in staggering losses of biodiversity and population declines in many species over the past two centuries. Associated with these declines are potential adverse effects linked to small population sizes, including loss of genetic diversity and increased levels of inbreeding. Here, we leverage DNA sequencing from museum specimens to examine genetic variation between historic and contemporary populations of four species of warblers (Aves, Setophaga ) that vary with respect to degree of population changes over this period. To explore the genetic impacts of varying population declines, we gathered polymorphism data at 157 PCR-amplified loci in 341 individuals sampled in two time periods—historic (1789–1955) vs contemporary (2001–2020). Results For all four species, we observed decreases in nucleotide diversity and heterozygosity in contemporary data sets compared to historic data sets. In three species, this loss was accompanied by a corresponding increase in inbreeding coefficient F IS. We find that these genetic diversity declines correspond to declining contemporary effective population sizes (Ne) over deeper time scales, as well as fluctuations in contemporary estimates of Ne. Conclusion Our findings suggest that loss of genetic diversity resulting from historic population declines persists over time (50–100 years), even when population trajectories later stabilize. Our results highlight the utility of long-term genetic temporal comparisons to reveal hidden genetic diversity loss and reveal important considerations for managing genetic diversity loss.

Background Many municipalities in rural areas of Korea are facing population decline due to the aging population phenomenon. This study examined the relationship between residing in municipalities facing population decline and satisfaction with nearby healthcare infrastructure in older aged adults. Methods The 2021 Korea Community Health Survey (KCHS) data were used. Municipalities were classified as those not facing population decline, those at risk, and those facing population decline based on the Population Decline Index. The association between residing in municipalities facing population decline and satisfaction with nearby healthcare infrastructure was examined cross-sectionally using a multi-level logistic regression analysis. Satisfaction with available public transportation was concomitantly examined as it is related to accessing healthcare services. Results Of the 58,568 individuals aged 65 years or above analyzed, 27,471 (46.9%) adults were residing in municipalities without population decline, 4,640 (7.9%) adults in municipalities at risk of population decline, and 26,457 (45.2%) in municipalities with population decline. Individuals living in municipalities with population decline were more likely to be dissatisfied with nearby healthcare infrastructure (OR 1.76, 95% CI 1.41–2.20). Similar tendencies were found for public transportation infrastructure (OR 1.67, 95% CI 1.38–2.03). Conclusions Individuals residing in municipalities with declining populations are more likely to report dissatisfaction with nearby healthcare infrastructure and public transportation. These findings emphasize the importance of providing adequate medical infrastructure to reduce potential health-related disparities.