UNASSIGNED: Cancer is a disease that affects nearly all multicellular life, including the broad and diverse taxa of Aves. While little is known about the factors that contribute to cancer risk across Aves, life history trade-offs may explain some of this variability in cancer prevalence. We predict birds with high investment in reproduction may have a higher likelihood of developing cancer. In this study, we tested whether life history traits are associated with cancer prevalence in 108 species of birds.
UNASSIGNED: We obtained life history data from published databases and cancer data from 5,729 necropsies from 108 species of birds across 24 taxonomic orders from 25 different zoological facilities. We performed phylogenetically controlled regression analyses between adult body mass, lifespan, incubation length, clutch size, sexually dimorphic traits, and both neoplasia and malignancy prevalence. We also compared the neoplasia and malignancy prevalence of female and male birds.
UNASSIGNED: Providing support for a life history trade-off between somatic maintenance and reproduction, we found a positive relationship between clutch size and cancer prevalence across Aves. There was no significant association with body mass, lifespan, incubation length, sexual dimorphism, and cancer.
UNASSIGNED: Life history theory presents an important framework for understanding differences in cancer defenses across various species. These results suggest a trade-off between reproduction and somatic maintenance, where Aves with small clutch sizes get less cancer.

Myoglobin (Mb) mediates oxygen diffusion and storage in muscle tissue and thus is important for the energy utilization and activity of animals. Birds generally have a high body temperature, and most species also possess the capability of powered flight. Both of these require high levels of aerobic metabolism. Within endothermic mammals, bats also independently evolved flight. Although the functional evolution of myoglobins in deep-diving amniote vertebrates has been well-studied, the functional evolution of myoglobin since the origins of both birds and bats is unclear. Here, with Mb-coding sequences from >200 extant amniote species, we reconstructed ancestral sequences to estimate the functional properties of myoglobin through amniote evolution. A dramatic change in net surface charge on myoglobin occurred during the origin of Aves, which might have been driven by positively selected amino acid substitutions that occurred on the lineage leading to all birds. However, in bats, no change in net surface charge occurred and instead, the Mb genes show evidence of strong purifying selection. The increased net surface charge on bird myoglobins implies an adaptation to flight-related endothermic and higher body temperatures, possibly by reducing harmful protein aggregations. Different from the findings of net surface charge, myoglobins of extant birds show lower stability compared with other amniotes, which probably accelerates the rate of oxygen utilization in muscles. In bats and other mammals, higher stability of Mb may be an alternative pathway for adaptation to endothermy, indicating divergent evolution of myoglobin in birds and bats.

Inflammasomes are multiprotein complexes that form in response to ligands originating from pathogens as well as alterations of normal cell physiology caused by infection or tissue damage. These structures engage a robust inflammatory immune response that eradicates environmental microbes before they cause disease, and slow the growth of bona fide pathogens. Despite their undeniable utility in immunity, inflammasomes are radically reduced in birds. Perhaps most surprising is that, within all birds, NLRP3 is retained, while its signaling adapter ASC is lost, suggesting that NLRP3 signals via a novel unknown adapter. Crocodilian reptiles and turtles, which share a more recent common ancestor with birds, retain many of the lost inflammasome components, indicating that the deletion of inflammasomes occurred after birds diverged from crocodiles. Some bird lineages have even more extensive inflammasome loss, with songbirds continuing to pare down their inflammasomes until only NLRP3 and CARD8 remain. Remarkably, songbirds have lost caspase-1 but retain the downstream targets of caspase-1: IL-1β, IL-18, and the YVAD-linker encoding gasdermin A. This suggests that inflammasomes can signal through alternative proteases to activate cytokine maturation and pyroptosis in songbirds. These observations may reveal new contexts of activation that may be relevant to mammalian inflammasomes and may suggest new avenues of research to uncover the enigmatic nature of the poorly understood NLRP3 inflammasome.

The Americas hold the greatest bird diversity worldwide. Likewise, ectoparasite diversity is remarkable, including ticks of the Argasidae and Ixodidae families - commonly associated with birds. Considering that ticks have potential health implications for humans, animals, and ecosystems, we conducted a systematic review to evaluate the effects of bioclimatic, geographic variables, and bird species richness on tick infestation on wild birds across the Americas. We identified 72 articles that met our inclusion criteria and provided data on tick prevalence in wild birds. Using Generalized Additive Models, we assessed the effect of environmental factors, such as habitat type, climatic conditions, bird species richness, and geographic location, on tick infestation. Our findings show that most bird infestation case studies involved immature ticks, such as larvae or nymphs, while adult ticks represented only 13% of case studies. We found birds infested by ticks of the genera Amblyomma (68%), Ixodes (22%), Haemaphysalis (5%), Dermacentor (1%), and Rhipicephalus (0.8%) in twelve countries across the Americas. Our findings revealed that temperature variation and bird species richness were negatively associated with tick infestation, which also varied with geographic location, increasing in mid-latitudes but declining in extreme latitudes. Our results highlight the importance of understanding how environmental and bird community factors influence tick infestation in wild birds across the Americas and the dynamics of tick-borne diseases and their impact on biodiversity.

Hard ticks (Acari: Ixodidae) are the economically and ecologically most important blood-sucking arthropod vectors that can transmit disease agents under temperate climate. In this group, the highest number of species (currently nearing 270) belongs to the genus Ixodes. For this review, more than 400 papers related to this genus in the context of Russia were checked for data on the host records, locations of collection, as well as ecology of assigned tick species. This monograph compensates for the lack of a similarly comprehensive English-language overview of Ixodes species in the region of Russia for nearly half century, and also makes a large set of data easily available for international readers, which is especially important if the original source is difficult to access from outside this country. In addition, the data from a significant number of papers on this topic available only in the Russian language are made accessible through this work.

A fundamental question in dinosaur evolution is how they adapted to long-term climatic shifts during the Mesozoic and when they developed environmentally independent, avian-style acclimatization, becoming endothermic.1,2 The ability of warm-blooded dinosaurs to flourish in harsher environments, including cold, high-latitude regions,3,4 raises intriguing questions about the origins of key innovations shared with modern birds,5,6 indicating that the development of homeothermy (keeping constant body temperature) and endothermy (generating body heat) played a crucial role in their ecological diversification.7 Despite substantial evidence across scientific disciplines (anatomy,8 reproduction,9 energetics,10 biomechanics,10 osteohistology,11 palaeobiogeography,12 geochemistry,13,14 and soft tissues15,16,17), a consensus on dinosaur thermophysiology remains elusive.1,12,15,17,18,19 Differential thermophysiological strategies among terrestrial tetrapods allow endotherms (birds and mammals) to expand their latitudinal range (from the tropics to polar regions), owing to their reduced reliance on environmental temperature.20 By contrast, most reptilian lineages (squamates, turtles, and crocodilians) and amphibians are predominantly constrained by temperature in regions closer to the tropics.21 Determining when this macroecological pattern emerged in the avian lineage relies heavily on identifying the origin of these key physiological traits. Combining fossils with macroevolutionary and palaeoclimatic models, we unveil distinct evolutionary pathways in the main dinosaur lineages: ornithischians and theropods diversified across broader climatic landscapes, trending toward cooler niches. An Early Jurassic shift to colder climates in Theropoda suggests an early adoption of endothermy. Conversely, sauropodomorphs exhibited prolonged climatic conservatism associated with higher thermal conditions, emphasizing temperature, rather than plant productivity, as the primary driver of this pattern, suggesting poikilothermy with a stronger dependence on higher temperatures in sauropods.

UNASSIGNED: From passive acoustic monitoring (PAM) recordings, the vocal activity rate (VAR), vocalizations per unit of time, can be calculated and is essential for assessing bird population abundance. However, VAR is subject to influences from a range of factors, including species and environmental conditions. Identifying the optimal sampling design to obtain representative acoustic data for VAR estimation is crucial for research objectives. PAM commonly uses temporal sampling strategies to decrease the volume of recordings and the resources needed for audio data management. Yet, the comprehensive impact of this sampling approach on VAR estimation remains insufficiently explored.
UNASSIGNED: In this study, we used vocalizations extracted from recordings of 12 bird species, taken at 14 PAM stations situated in subtropical montane forests over a four-month period, to assess the impact of temporal sampling on VAR across three distinct scales: short-term periodic, diel, and hourly. For short-term periodic sampling analysis, we employed hierarchical clustering analysis (HCA) and the coefficient of variation (CV). Generalized additive models (GAMs) were utilized for diel sampling analysis, and we determined the average difference in VAR values per minute for the hourly sampling analysis.
UNASSIGNED: We identified significant day and species-specific VAR fluctuations. The survey season was divided into five segments; the earliest two showed high variability and are best avoided for surveys. Data from days with heavy rain and strong winds showed reduced VAR values and should be excluded from analysis. Continuous recordings spanning at least seven days, extending to 14 days is optimal for minimizing sampling variance. Morning chorus recordings effectively capture the majority of bird vocalizations, and hourly sampling with frequent, shorter intervals aligns closely with continuous recording outcomes.
UNASSIGNED: While our findings are context-specific, they highlight the significance of strategic sampling in avian monitoring, optimizing resource utilization and enhancing the breadth of monitoring efforts.

Mites of the family Syringophilidae (Acariformes: Prostigmata: Cheyletoidea) are permanent and obligatory parasites of birds. This study presents an analysis of mite material collected from 22 avian species belonging to the family Paradisaeidae (Passeriformes), revealing the presence of four mite species belonging to four genera: Syringophiloidus attenboroughi n. sp., Peristerophila regiusi n. comb., Picobia frankei, and Gunabopicobia garylarsoni. In the present work, the genus Neoperisterophila is synonymized with the genus Peristerophila. While the genera Syringophiloidus and Picobia were expectedly found on paradisaeid birds, given their prevalence in passerines, the presence of Peristerophila and Gunabopicobia was intriguing, suggesting potential host-switching events. The specificity of these mites varies, with some showing occurrence on hosts of closely related genera and others infesting phylogenetically distant hosts. Notably, the distribution of specific mite species on the Birds-of-Paradise appears to be influenced by both long coevolutionary histories and incidental contacts between often unrelated or intergeneric hybrid species of paradisaeid birds. Furthermore, our research of 104 specimens from 22 Birds-of-Paradise species shows generally low infestation rates across the studied species, suggesting a nuanced interaction between these mites and their avian hosts. Additionally, our network analysis provides a deeper understanding of these host-parasite interactions, revealing a high level of specialization and complexity in these ecological relationships.

The orexinergic/hypocretinergic system, while having several roles, appears to be a key link in the balance between arousal and food intake. In birds, to date, this system has only been examined anatomically in four species, all with brains smaller than 3.5 g and of limited phylogenetic range. Here, using orexin-A immunohistochemistry, we describe the distribution, morphology, and nuclear parcellation of orexinergic neurons within the hypothalami of a Congo gray and a Timneh gray parrot, a pied crow, an emu, and a common ostrich. These birds represent a broad phylogeny, with brains ranging in size from 7.85 to 26.5 g. Within the hypothalami of the species studied, the orexinergic neurons were organized in two clusters, and a densely packed paraventricular hypothalamic nucleus cluster located within the medial hypothalamus (Hyp), but not contacting the ventricle, and a more loosely packed lateral hypothalamic cluster in the lateral Hyp. Stereological analysis revealed a strong correlation, using phylogenetic generalized least squares regression analyses, between brain mass and the total number of orexinergic neurons, as well as soma parameters such as volume and area. Orexinergic axonal terminals evinced two types of boutons, larger and the smaller en passant boutons. Unlike the orexinergic system in mammals, which has several variances in cluster organization, that of the birds studied, in the present and previous studies, currently shows organizational invariance, despite the differences in brain and body mass, phylogenetic relationships, and life-histories of the species studied.

Species are altering their ranges as a response to climate change, but the magnitude and direction of observed range shifts vary considerably among species. The ability to persist in current areas and colonize new areas plays a crucial role in determining which species will thrive and which decline as climate change progresses. Several studies have sought to identify characteristics, such as morphological and life-history traits, that could explain differences in the capability of species to shift their ranges together with a changing climate. These characteristics have explained variation in range shifts only sporadically, thus offering an uncertain tool for discerning responses among species. As long-term selection to past climates have shaped species\' tolerances, metrics describing species\' contemporary climatic niches may provide an alternative means for understanding responses to on-going climate change. Species that occur in a broader range of climatic conditions may hold greater tolerance to climatic variability and could therefore more readily maintain their historical ranges, while species with more narrow tolerances may only persist if they are able to shift in space to track their climatic niche. Here, we provide a first-filter test of the effect of climatic niche dimensions on shifts in the leading range edges in three relatively well-dispersing species groups. Based on the realized changes in the northern range edges of 383 moth, butterfly, and bird species across a boreal 1,100 km latitudinal gradient over c. 20 years, we show that while most morphological or life-history traits were not strongly connected with range shifts, moths and birds occupying a narrower thermal niche and butterflies occupying a broader moisture niche across their European distribution show stronger shifts towards the north. Our results indicate that the climatic niche may be important for predicting responses under climate change and as such warrants further investigation of potential mechanistic underpinnings.