Patterns of extinction risk can vary across taxa, with species of some groups being particularly vulnerable to extinction. Rails (Aves: Rallidae) represent one of the most extreme yet well-documented cases of mass extinction within a modern vertebrate group. Between 54 and 92% of rail species became extinct following waves of human contact during both the Holocene and the Anthropocene eras, and a third of the extant species are currently threatened or near-threatened. Here, we (1) examine extinction filters through consecutive human contacts with rails, investigating the role of intrinsic life-history traits and (2) investigate the drivers of contemporary vulnerability. During the most recent wave of extinction, we found that body size was an important correlate of rail extinctions, with both smaller and larger bodied species more likely to become extinct. Island endemism and small clutch size were the strongest predictors of contemporary vulnerability. Overall, island endemic rails tend to follow the same trajectory as extinct species, suffering mostly from invasive predators and overhunting, but with different traits targeted contemporarily compared to past extinctions. Moreover, modern anthropogenic threats have created the potential for new intricate pathways – or a contemporary ‘field of bullets’ – making future vulnerability potentially less predictable.

For centuries, fossils from the Maastrichtian type locality and adjacent quarries have provided key evidence of vertebrate diversity during the latest Cretaceous, yet until recently the Maastrichtian type area had revealed no important insights into the evolutionary history of birds, one of the world’s most conspicuous groups of extant tetrapods. With the benefit of high-resolution micro-CT scanning, two important avian fossils from the Maastrichtian type area have now been examined in detail, offering profound, complementary insights into the evolutionary history of birds. The holotype specimens of these new taxa, Janavis finalidens Benito, Kuo, Widrig, Jagt and Field, 2022, and Asteriornis maastrichtensis Field, Benito, Chen, Jagt and Ksepka, 2020, were originally collected in the late 1990s, but were only investigated in detail more than twenty years later. Collectively, Janavis and Asteriornis provide some of the best evidence worldwide regarding the factors that influenced stem bird extinction and crown bird survivorship through the Cretaceous-Palaeogene transition, as well as insights into the origins of key anatomical features of birds such as an extensively pneumatised postcranial skeleton, a kinetic palate, and a toothless beak. Asteriornis also provides scarce evidence of a Cretaceous-aged divergence time calibration within the avian crown group, while together, Janavis and Asteriornis constitute the only documented co-occurrence of crown birds and non-neornithine avialans. Here, we review key insights into avian evolutionary history provided by these discoveries from the Maastrichtian stratotype, document undescribed and newly discovered Maastrichtian fossils potentially attributable to Avialae and provide the first histological data for the holotype of Asteriornis, illustrating its skeletal maturity at the time of its death.

Biodiversity systematic monitoring programmes have been expanding across the globe, especially in protected areas (PAs). Amongst sustainable-use PAs, medium- to large-sized mammals and birds comprise crucial groups to monitor, given their importance to forest functionality and subsistence for local residents. Here, we used 6 years of community-based monitoring data from a sustainable-use PA in the Brazilian Amazonia (Tapajós–Arapiuns Extractive Reserve) to examine the influence of anthropogenic stressors and time on the density and biomass of forest mammal and bird game species. We further assessed trends in population density of target groups over the period. A total of 1915 km of line-transect surveys were completed by trained local monitors along eight established transects, providing data from 12 medium-sized and five large-sized game genera. Generalized linear mixed models of all medium-sized species, all large species and four individual taxa (Tinamidae, Dasyproctidae, primates and Cervidae) showed that some species (e.g., Dasyprocta croconota) exhibited great density, whereas others (e.g., Tapirus terrestris and Tayassu pecari) were rarely detected. Anthropogenic variables did not affect the density and biomass of the overall medium-sized and large vertebrates. Dasyproctidae, Tinamidae and primates were the only taxa influenced by anthropogenic stressors, with negative influence occurring only for Tinamidae. Moreover, density of groups and taxa remained stable throughout the period in the Reserve, although the frequency of some species may indicate past population losses. Continuation of this monitoring programme is required to improve understanding of population fluctuations, but over the 6 years studied, game population density and biomass were not linked to anthropogenic stressors.

Antioquia Brushfinch Atlapetes blancae is a recently rediscovered Colombian microendemic species with a restricted distribution. Although the species might use a variety of habitats, current information suggests that it is a shrubland specialist. It is categorised as “Critically Endangered” because due to habitat loss its population has been estimated to be smaller than 50 individuals. Such estimates are based on indirect measurements of its population and assumptions regarding its restricted range/habitat. We provide the first direct population estimates and adult sex ratio for seven localities, using mark-resighting techniques. Individuals were captured using mist-nets, bled, and colour banded. Subsequently, we performed censuses along transects to record banded and non-banded individuals. Population estimates were obtained using the classic closed population mark-resighting model. In addition, we used the abundance–area relationship to estimate population size at other sites where the species has been previously recorded. Finally, individuals were sexed by amplifying the Z and W-linked Chromo-Helicase DNA-binding gene (CHD) genes. In total, we banded 55 individuals at four locations. Summarising across the seven sampled localities, we found that the population is most likely composed of 109 individuals in the 122 ha sampled. Based on the abundance–area relationship, we estimated that the population of Antioquia Brushfinch could be as large as 405 individuals in 322 ha of suitable habitat. We found that male/female sex ratio was 0.45 (95% confidence interval [CI] 0.32–0.6) and that it was not significantly biased. Our results suggest that the population of Antioquia Brushfinch is at least eight times larger than suggested by secondary information. We found that populations are properly structured at least regarding sex ratio, although we caution for further research on sex biases of immature and juvenile individuals. We recommend that future studies should focus on population trends and the impact of habitat transformation on the demography of this iconic species.

Avian malaria parasites or haemosporidia are found in bird species worldwide. This special issue focuses on 3 most commonly studied genera: Haemoproteus, Plasmodium and Leucocytozoon. Seven research articles and reviews are provided to illustrate the breadth of knowledge of the diversity of avian malaria parasites in different regional habitats and across bird species, and the use of avian haemosporidian systems to examine host–parasite eco-evolutionary questions.

Understanding how selective logging affects biodiversity is crucial to planning cost-effective conservation strategies in tropical forests, yet there is limited understanding of its impacts on fauna functional diversity in the tropical Americas. We assessed how selective logging intensification and time since logging influence multiple metrics of fauna functional integrity in the Brazilian Amazon by collecting bird and dung beetle data within 48 logging management units that had experienced varying exploitation intensities between 1.5–2.0 and 5.0–6.0 years before the faunal surveys. We investigated assemblage responses and used functional attributes to assess changes in functional diversity, specialization, originality and species rarity. Using point counts and pitfall traps, we collected 5081 records of 182 bird species and 7892 dung beetles from 45 species. Logging intensification led to significant declines in most dung beetle responses and bird body mass, whereas time since logging was a key driver of dung beetle and bird functional and taxonomic diversity. Our study presents novel empirical evidence of how logging intensification effects vary across taxa, ecological metrics and time since logging, which is key to informing forest conservation and further investigating environmental degradation impacts on tropical biodiversity.

Investigations of the parasites associated with extinct avian species provide unique insights into the ecology and evolution of both hosts and their parasitic counterparts. In the present paper, a new quill mite species, Peristerophila conuropsis sp. n., belonging to the family Syringophilidae (Prostigmata: Cheyletoidea) is described from the Carolina parakeet Conuropsis carolinensis Linnaeus (Psittaciformes: Psittacidae). This new species was collected from museum dry skin of the Carolina parakeet, the only native representative of the Psittacidae in the United States, which was an abundant resident of the southeastern and midwestern states and has been extinct in the beginning of the 20th century. Comment on the current taxonomic state and host associations of the genus Peristerophila are provided. Based on the host associations and habitats occupied by Peristerophila and related genera on parrots, it is hypothesized with the high probability that P. conuropsis has been extinct along with its host.