Bird Populations Research Articles

Was extinction of New Zealand's avian megafauna an unavoidable consequence of human arrival?

Human overexploitation contributed strongly to the loss of hundreds of bird species across Oceania, including nine giant, flightless birds called moa. The inevitability of anthropogenic moa extinctions in New Zealand has been fiercely debated. However, we can now rigorously evaluate their extinction drivers using spatially explicit demographic models capturing species-specific interactions between moa, natural climates and landscapes, and human colonists. By modelling the spatial abundance and extinction dynamics of six species of moa, validated against demographic and distributional inferences from the fossil record, we test whether their extinctions could have been avoided if human colonists moderated their hunting behaviours. We show that harvest rates of both moa birds (adults and subadults) and eggs are likely to have been low, varying between 4.0-6.0% for birds and 2.5-12.0% for eggs, annually. Our modelling, however, indicates that extinctions of moa could only have been avoided if Polynesian colonists maintained unrealistically expansive no-take zones (covering at least half of New Zealand's land area) and held their annual harvest rates to implausible levels (just 1% of bird populations per annum). Although too late for moa, these insights provide valuable lessons and new computational approaches for conserving today's endangered megafauna.

Detection of Toxoplasma gondii in Brain Tissues of Pet Birds with Neurological Symptoms Using Loop-Mediated Isothermal Amplification (LAMP) and PCR.

This study seeks to close this divide by assessing the occurrence of Toxoplasma gondii (T. gondii) in the brain tissues of pet birds displaying neurological symptoms, utilizing Nested Polymerase Chain Reaction (PCR) and Loop-mediated Isothermal Amplification (LAMP) methods. Furthermore, it aims to evaluate and contrast the sensitivity and specificity of different diagnostic procedures. Seventy bird samples, consisting of 50 sick and 20 asymptomatic samples, were assessed using various methods. Brain tissue DNA was isolated and then analyzed using nested PCR and LAMP assays targeting the T. gondii B1 gene and RE gene. Sensitivity and specificity assessments were conducted, and statistical evaluations were made using SPSS software. Our findings revealed that no T. gondii cysts were detected in the smear preparations. However, T. gondii DNA was found in 6% of the sick birds using nested PCR, and LAMP identified T. gondii DNA in 8% of these individuals. Both techniques demonstrated a high level of specificity, with LAMP showing higher sensitivity and faster processing times than nested PCR. These results significantly contribute to our understanding of toxoplasmosis and highlight the reliability and potential for the widespread use of these diagnostic techniques, providing reassurance and confidence in their effectiveness. The study underscores the importance of molecular diagnostics in promptly identifying and treating toxoplasmosis in birds. This enhances our understanding and control of the disease and underscores the significant impact of this research. The potential for further studies using more extensive and diverse bird populations to enhance surveillance and prevention strategies against T. gondii infections is promising. It should be actively pursued, giving us hope for a better future in avian health.

Endocrine and molecular regulation of seasonal avian immune function.

Birds have evolved seasonal adaptations in multiple aspects of the innate and adaptive immune systems. Seasonal immunological adaptations are crucial for survival in harsh environmental conditions and in response to increased prevalence of acute and chronic diseases. Similar to other vertebrates, birds exhibit remarkable plasticity in cytokine production, chemotaxis, phagocytosis and inflammation across the year. In this review, we provide a comparative perspective on seasonal rhythms in bird immune function. We describe advances in our understanding of annual changes in immune cells and responses to innate and adaptive immune challenges. Then, the role of glucocorticoids, sex steroids, thyroid hormones (THs) and melatonin to act as immunomodulators is described. We then discuss the impact of a major and emerging disease, the high pathogenicity avian influenza, as one of the most critical seasonal diseases with significant implications for poultry and wild bird populations. The review identifies the need to enhance our knowledge of annual rhythms in immune cells and tissues in birds, at molecular, cellular and hormonal levels across the year. Moreover, there is a significant absence of information on sex-specific seasonal variation in immune function. Understanding seasonal immune system dynamics will aid in addressing the negative impacts of pathogenic diseases, minimize global economic losses and aid conservation efforts.This article is part of the Theo Murphy meeting issue 'Circadian rhythms in infection and immunity'.

Screening Wild Birds for Tick-Borne Zoonotic Pathogens in Portugal.

Wild birds may be involved in the transmission of agents of infectious diseases, including zoonoses, a circumstance which raises a number of public and animal health issues. Migratory bird species play a significant role in the introduction of tick-borne pathogens to new geographic areas, contributing to the dissemination of various etiological agents. This preliminary study aimed to assess the occurrence of four potentially zoonotic pathogens (Hepatozoon spp., Borrelia spp., Babesia spp. and Theileria spp.) in the wild birds of Portugal. Blood and tissue samples were taken from 103 birds admitted at wildlife rehabilitation centers. Through the use of conventional PCR, our findings indicate no evidence of the circulation of these pathogens among the studied bird populations in the region. In the One Health context, it is relevant to understand how faraway avian populations play a role in the epidemiology of infectious diseases. Further molecular studies are needed to deepen the knowledge of avian piroplasmosis, borreliosis and hepatozoonosis.

Perancangan Alat Inkubator Anak Murai Menggunakan Sensor Suhu DHT11 Dengan Mikrokontroller IoT

The development of technology and the modernization of electronic equipment along with the progress of the times has caused fundamental changes in human life, where humans now need everything that is completely automatic, practical and effective. It's not only humans who need this practical technology, animals also need this technological equipment to survive. The magpie bird population is an important thing that must be considered, because the large amount of tree felling in the magpie bird's habitat makes it difficult for magpie birds to breed in their habitat. To restore the magpie bird population, now many people are starting to breed magpie birds in their homes to resemble their habitat in the forest, but breeding magpie birds is very difficult. To overcome this problem, it is necessary to design a temperature control device in an IoT-based incubator that can make it easier for magpie bird breeders to regulate the temperature and can monitor the temperature in the incubator via cellphone, so that the magpie chicks that have been separated from their parents can grow well without any problems. physical disabilities or dead magpie chicks so that the magpie bird population can increase.

Plio-Pleistocene Environmental Changes Drove the Settlement of Aotearoa New Zealand by Australian Open-Habitat Bird Lineages.

In a changing environment, vacant niches can be filled either by adaptation of local taxa or range-expanding invading species. The relative tempo of these patterns is of key interest in the modern age of climate change. Aotearoa New Zealand has been a hotspot of biogeographic research for decades due to its long-term isolation and dramatic geological history. An island with high levels of faunal endemicity, it is a system well suited to studying the relative effects of insitu evolution versus dispersal in determining faunal assemblages, while its turbulent climate and geological history provide valuable insights into the evolutionary impacts of environmental changes. Such investigations are of urgent importance given predicted climate change and human impacts rapidly affecting environments globally. Here, we analyse the divergence dates of nearly all endemic Aotearoa New Zealand bird species from their overseas relatives to assess the role of environmental changes in driving speciation and colonisation, with special regard to cooling climate during the Pliocene and Pleistocene. We uncover a wave of colonisation events by Australian open-habitat adapted species since the Pliocene that peaked at the beginning of the Pleistocene. Furthermore, we highlight an even distribution of divergence dates in forest-adapted taxa through time, consistent with millions of years of extensive forest cover. Finally, we note parallels to the modern-day establishment of new bird populations from Australia and suggest this is largely influenced by anthropogenic land-use patterns. This research contributes to the growing body of work recognising the long-lasting impacts of Pleistocene climate change on Aotearoa New Zealand's avifauna, and reinforces biological invasions as a key evolutionary response to changing environmental conditions.

Bird Species Detection Net: Bird Species Detection Based on the Extraction of Local Details and Global Information Using a Dual-Feature Mixer.

Bird species detection is critical for applications such as the analysis of bird population dynamics and species diversity. However, this task remains challenging due to local structural similarities and class imbalances among bird species. Currently, most deep learning algorithms focus on designing local feature extraction modules while ignoring the importance of global information. However, this global information is essential for accurate bird species detection. To address this limitation, we propose BSD-Net, a bird species detection network. BSD-Net efficiently learns local and global information in pixels to accurately detect bird species. BSD-Net consists of two main components: a dual-branch feature mixer (DBFM) and a prediction balancing module (PBM). The dual-branch feature mixer extracts features from dichotomous feature segments using global attention and deep convolution, expanding the network's receptive field and achieving a strong inductive bias, allowing the network to distinguish between similar local details. The prediction balance module balances the difference in feature space based on the pixel values of each category, thereby resolving category imbalances and improving the network's detection accuracy. The experimental results using two public benchmarks and a self-constructed Poyang Lake Bird dataset demonstrate that BSD-Net outperforms existing methods, achieving 45.71% and 80.00% mAP50 with the CUB-200-2011 and Poyang Lake Bird datasets, respectively, and 66.03% AP with FBD-SV-2024, allowing for more accurate location and species information for bird detection tasks in video surveillance.

Feeding behavior and prey characteristics of great egrets (Ardea alba) in eco-friendly and conventional rice fields in South Korea

Rice fields are important wildlife habitats; however, intensive agricultural practices have reduced the population of farmland birds. As a high-level consumer, the great egret (Ardea alba) serves as an indicator of the overall biodiversity of rice fields. However, little is known about the effects of farming methods on the feeding habitat selection of the great egret. Therefore, we examined the influence of eco-friendly and conventional farming methods on prey characteristics and great egret feeding behavior in rice field ecosystems. We employed focal observations and trap-based sampling to quantify prey characteristics and great egret feeding behaviors in eco-friendly and conventional rice fields. Great egrets showed more hunting attempts per minute and a higher intake rate in conventional fields, but feeding efficiency did not differ. Moreover, they consumed larger loaches in eco-friendly fields than in conventional fields. Great egrets exhibited slower feeding behaviors in eco-friendly fields due to the increased handling time of larger prey, such as loaches. Eco-friendly fields supported a higher abundance of larger-sized loaches than conventional fields, indicating their potential for supporting a higher abundance of great egrets. Our findings highlight the importance of sustainable farming practices for the conservation of the great egret.

Ecological Drivers of Molt-Breeding Overlap, an Unusual Life-History Strategy of Small-Island Birds?

Terrestrial bird populations on small, species depauperate islands often experience selection for generalist foraging traits via ecological release; however, it is unclear how island conditions may uniquely influence other life-history characteristics of small-island birds, such as the unusually high rates of molt-breeding overlap exhibited on the island of Grenada. To explore this question, we collected data on the life cycles and diets of 10 commonly occurring Grenadian bird species to assess the degree of generalist foraging and evaluate how seasonal patterns in diet niche breadth and diet overlap among species relates to the high rates of molt-breeding overlap. We evaluated three hypotheses explaining drivers of molt-breeding overlap (constraints on molt rate, unpredictable food abundance, and limited duration of food abundance), and suggest that widespread overlap in small-island tropical communities may be the result of generalist foraging adaptations and restricted time periods of sufficient invertebrate availability for successful breeding and molt to occur. We found that these species typically exhibited low breeding period seasonality followed by synchronized peaks in molt intensity and molt-breeding overlap during peak rainfall and high invertebrate abundance. There was also greater diet overlap and wider niche widths of invertebrate resources in the wet season when molt-breeding overlap occurred, and greater niche partitioning of invertebrate items among species in the dry season suggesting that competitive interactions for invertebrates were stronger in the dry season. Birds also shared more plant food sources in the dry season when invertebrate abundance is low, though seasonal differences in plant diet diversity and niche width varied by species. These results provide evidence that scarce invertebrate resources and competition likely limit productivity and molt/self-maintenance in these island-adapted, species-depauperate communities, and drive high rates of molt-breeding overlap, a relatively uncommon life-history strategy.

A morphological survey of avian Haemosporida in Colombian wild birds

Introduction: Infection by protozoan haemoparasites causing malaria in birds is chronic and can lead to physical, reproductive, and behavioral alterations, resulting in a decline in the populations of affected wild birds. Objective: To identify parasitic agents causing avian malaria in a wild bird population in Jardin (Antioquia, Colombia) through blood smears and to explore bird-level factors associated with positivity. Methods: A descriptive cross-sectional study was conducted with non-probabilistic convenience sampling. Blood samples were obtained from wild birds captured with mist nets. Each bird was characterized according to its genus, species, sex, and age group. Three blood smears per bird were prepared and examined for parasitic structures from Haemoproteus, Leucocytozoon, and Plasmodium genera. Descriptive statistics and the association between study variables and the dichotomous outcome of blood smear analysis (positive or negative) using Fisher's exact test. Results: A total of 46 wild birds from 20 different species of the orders Passeriformes and quasi-Passeriformes were captured at six different locations in the study municipality (between 1,665 and 2,053 m.a.s.l.) in July 2022. Structures compatible with Haemosporida causing avian malaria were found, with a general infection frequency of 34.8% (16/46). Among the birds, 32.6% (15/46) were positive for Plasmodium spp., 6.5% (3/46) for Haemoproteus spp., and 4.3% (2/46) for Leucocytozoon spp. In addition, 6.5% (3/46) of the birds were coinfected with 2 or 3 of the agents of interest. An association was found between Plasmodium spp. infection and age group when the bird was defined as an adult (p=0.050). Conclusion: This study contributes to the knowledge of haemoparasites in wild birds in Colombia, reporting the presence of avian malaria in the study area. Further research is required on the molecular identification of protozoan haemoparasites, pathogenicity, the health status of these birds, and the attributable impact on their populations.

A Spatial Multi Criteria Decision Analysis (SMCDA) to map the risk of avian influenza in Lazio and Toscana (central Italy).

Avian influenza (AI) is a global concern, affecting wild and domestic bird populations worldwide. Environmental conditions facilitating the presence of wild birds and a consistent domestic bird population contribute to the introduction and spread of AI within a territory. This study focuses on the identification of major risk areas for AI in the Lazio and Toscana Regions of central Italy using Spatial Multi-Criteria Decision Analysis (SMCDA). Through the integration of eleven risk factors regarding domestic bird farms and facilities, wild birds density, water bodies, and roads network, a suitability map for AI introduction and spread was generated. The findings reveal that approximately 30% of Lazio and 20% of Toscana are at high risk for AI introduction and spread. Notably, the implementation of rigorous biosecurity measures in intensive poultry industries has significantly prevented the occurrence of AI outbreaks, even in areas considered at risk. The study emphasizes the importance of informed decision-making in AI risk management, highlighting the potential applications of the SMCDA in prioritizing surveillance efforts and planning control programs. Furthermore, it underscores the need for continuous data updating and comprehensive preventive strategies to address the complex dynamics of AI transmission and safeguard both poultry and human health.

The Flame of the Forest (Butea monosperma) and its Mutualistic Interaction with Birds in Summer from Jamkhed Tahsil, Dist. Ahmednagar.

The flame of the forest (Butea monosperma), a species native to the Indian subcontinent, play a vital role in supporting biodiversity, particularly in its interactions with avian species in rural and semi-arid areas like Jamkhed tahsil in Ahmednagar district, Maharashtra. This study aims to explore the avian fauna of Jamkhed and the importance of butea monosperma in sustaining bird populations during summer season. We emphasize conservation efforts and ecological singnificance by highlighting the relationships between the region’s flora and fauna through this investigation. Field surveys were conducted during early morning and late afternoon from February-April 2024.Total 56 bird species was recorded. Through field observation explores the butea monosperma role as a food source, nesting and roosting habitat for birds. Result highlight that Butea monosperma is a keystone species in supporting avian population by providing nector during the dry season, shelter for nesting and promoting ecological balance through bird-mediated pollination. Birds contribute to the genetic diversity of Butea monosperma by facilitating cross-pollination between individual trees. This interaction ensures the tree's reproductive success and enhances its ability to regenerate and persist in the ecosystem.

First detection and diversity of astroviruses in wild migratory birds of Sakhalin Island, North Pacific.

Researchers have identified Avastrovirus as a significant genus of bird viruses, linked to various avian diseases such as enteritis, growth retardation, nephritis and hepatitis. These infections can cause substantial economic losses in agrocultureand have a widespread impact on global food production. Although there have been numerous studies on these viruses, most of them-mainly focuses on poultry. Research on astroviruses in wild bird populations has revealed a wide genetic diversity of these viruses, yet our understanding of their biological and ecological characteristics remains limited. In this study, we for the first time detected avastrovirus in wild migratory birds of the families Anatidae and Columbidae from Sakhalin Island, North Pacific Ocean. Phylogenetic analysis revealed the presence of Avastrovirus 2 in wild doves and Avastrovirus 3 in wild ducks. These findings provide valuable insights into the circulation of astroviruses in wild bird populations of Sakhalin Island, which lies along the East Asian-Australasian Flyway.

Immature Northern Gannets (Morus bassanus) increase colony attendance following highly pathogenic avian influenza

The emergence of Highly Pathogenic Avian Influenza (HPAI) H5N1 in wild bird populations in 2020 changed the landscape of this disease for seabird populations, including Northern Gannets Morus bassanus. In 2023, we photographed the three Northern Gannet colonies in Newfoundland and Labrador, Canada (Funk Island, Baccalieu Island and Cape St Mary's), following an HPAI outbreak in 2022 and documented an overall 43% decline in apparently occupied sites (AOS) from the last population survey in 2018. During the photo analyses, we assigned immature birds present in the core breeding area to one of four age categories according to their plumage characteristics, and estimated that 9% (inter‐colony variance ranging from 7 to 14%) of all AOS in 2023 hosted at least one immature bird, an increase compared with rates of 2% or less before the outbreak. Further, 16% of all immature birds present in the core breeding area showed evidence of breeding and were probably 2‐ and 3‐year‐old birds. Our results support the social competition theory whereby a higher proportion of immature and/or younger immature birds occupying an AOS within the core breeding area is observed following significant reductions in numbers of established breeders, suggesting the presence of a pool of immature birds capable of recruiting into the Newfoundland Northern Gannet breeding population and help its recovery.

Bird Diversity in Gangrar, Chittorgarh Rajasthan, India

Studying bird diversity in arid zones is vital for preserving biodiversity, understanding ecological processes, and addressing the environmental challenges specific to these unique and fragile ecosystems. This study aimed to investigate bird diversity in some selected places in Gangrar, examining the relationships between bird species and environmental factors. The study focused on three places, which are Nolagadri Ka Khera, Mansingh Ji Ka Khera, and Modsingh Ki Chawki. The study was conducted for 6 months (February 2024 – July 2024) weekly from 0600hrs to 1000hrs in the morning and 1600hrs to 1800hrs in the evening. The point count method was preferred and used for the survey. A total of 56 bird species which belong to 10 orders were identified in the study area. Order of Passeriformes was recorded with the highest species 33 (69.02%). While the order of Psittaciformes (2.45%), Gruiformes (1.23%), Accipitriformes (0.07%), and Bucerotiformes (0.07%) were recorded with the lowest species, (only one species) in the study area. Nolagadri Ka Khera has the highest number of individual species (527), while Modsingh Ki Chawki has 411 species and Mansingh Ji Ka Khera has 234 species. The bird diversity in Gangrar is influenced by many environmental and ecological factors which include, sparse vegetation consisting of grasses, shrubs, and scattered trees. The limitation of water in the Gangrar also contributes to the kind of species to thrive in the environment. Human influences affect the diversity of birds and they assist the birds and ensure the survival of the birds. The findings show the importance of acknowledging these kinds of ecosystems to maintain biodiversity and ensure the sustainability of bird populations.

West Nile Virus: An Update Focusing on Southern Europe.

West Nile Virus (WNV) is a zoonotic, vector-borne pathogen affecting humans and animals, particularly in Europe. The virus is primarily transmitted through mosquitoes that infect birds, which serve as the main reservoirs. Humans and horses are incidental hosts. This review focuses on the epidemiology of WNV in southern Europe, particularly its increasing prevalence. Methods included an extensive literature review and analysis of recent outbreaks. WNV is largely asymptomatic in humans, but a small percentage can develop West Nile neuroinvasive disease (WNND), leading to severe neurological symptoms and fatalities. Horses can also suffer from neurological complications, with high mortality rates. Climate change, migratory birds, and mosquito population dynamics contribute to the virus spread across Europe. Control efforts focus on vector management, and while vaccines are available for horses, none has been approved for humans. Surveillance, particularly of bird and mosquito populations, and further research into the virus molecular structure are crucial for understanding and mitigating future outbreaks.

Recurring incursions and dissemination of novel Eurasian-origin H5Nx avian influenza viruses in Atlantic Canada.

Wild birds are important hosts of influenza A viruses (IAVs) and play an important role in their ecology. The emergence of the A/goose/Guangdong/1/1996 H5N1 (Gs/GD) lineage marked a shift in IAV ecology, leading to recurrent outbreaks and mortality in wild birds from 2002 onwards. This lineage has evolved and diversified over time, with a recent important derivative being the 2.3.4.4b sub-lineage, which has caused significant mortality events in wild bird populations. An H5N1 clade 2.3.4.4b virus was transmitted into North America from Eurasia in 2021, with the first detection being in Newfoundland and Labrador in Atlantic Canada, and this virus and its reassortants then spread broadly throughout North America and beyond. Following the first 2021 detection, there have been three additional known incursions of Eurasian-origin strains into Atlantic Canada, a second H5N1 strain in 2022 and two H5N5 strains in 2023. In this study, we document a fifth incursion in Atlantic Canada that occurred in 2023 by another H5N5 strain. This strain spread throughout Atlantic Canada and into Quebec, infecting numerous species of wild birds and mammals. Genomic analysis revealed mammalian-adaptive mutations in some of the detected viruses (PB2-E627K and PB2-D701N) and mutations in the hemagglutinin (HA) and neuraminidase (NA) genes that are associated with enhanced viral fitness and avian transmission capabilities. Our findings indicate that this virus is continuing to circulate in wildlife, and confirms Atlantic Canada is an important North American entry point for Eurasian IAVs. Continued surveillance and genomic analysis of IAVs detected in the region is crucial to monitor the evolution of these viruses and assess potential risks to wildlife and public health.

Multi‐scale habitat selection and nest survival of whinchats and stonechats: implications for grassland conservation management

Effective management for endangered grassland birds requires a sound understanding of habitat requirements and factors shaping reproductive success. We studied multi‐level habitat selection of endangered whinchats Saxicola rubetra and locally increasing stonechats Saxicola rubicola in a nature reserve using Sentinel‐2 images, LiDAR data, and habitat variables measured onsite. We monitored nest fates, and estimated how the causes of nest mortality varied with nest initiation date. Further, we analyzed how nest‐site selection, precipitation, nest initiation date, and nest age influenced daily nest survival.At the landscape‐ and site‐level, both species primarily selected for territories in lightly farmed meadows. However, stonechats appeared to be less specialized and used most available habitat types. Within home‐ranges, both species selected for nest‐sites in fallow patches, but in contrast to stonechats, whinchats also selected for large viewsheds.In both species, the main causes of nest failure were predation by red foxes Vulpes vulpes, weather‐related factors, and nest desertion. In whinchats, the probability of nest desertion increased and predation risk decreased with nest initiation date, possibly due to better nest concealment in the later season. Daily nest survival decreased with nest age and precipitation in both species, and increased with nest initiation date in whinchats. None of the habitat variables examined were positively linked to daily nest survival, and viewshed was negatively related to whinchat daily nest survival.Our study suggests that extending core habitat may help to promote settlement and potentially reproductive success of whinchats. However, as habitat selection was not positively associated with daily nest survival, land management measures alone might not be sufficient to halt rapid population declines. To effectively conserve whinchats and other grassland bird populations, the causes of nest failures must be identified and addressed. Within the examined reserve and similar habitats, flood management and predator control may yield the biggest short‐term conservation gains.

Stochastic Models of Zoonotic Avian Influenza with Multiple Hosts, Environmental Transmission, and Migration in the Natural Reservoir.

Avian influenza virus type A causes an infectious disease that circulates among wild bird populations and regularly spills over into domesticated animals, such as poultry and swine. As the virus replicates in these intermediate hosts, mutations occur, increasing the likelihood of emergence of a new variant with greater transmission to humans and a potential threat to public health. Prior models for spread of avian influenza have included some combinations of the following components: multi-host populations, spillover into humans, environmental transmission, seasonality, and migration. We develop an ordinary differential equation (ODE) model for spread of a low pathogenic avian influenza virus that combines all of these factors, and we translate this into a stochastic continuous-time Markov chain model. Linearization of the ODE near the disease-free solution leads to the basic reproduction number , a threshold for disease extinction in both the ODE and Markov chain. The linearized Markov chain leads to a branching process approximation which provides an estimate for probability of disease extinction, i.e., probability no major disease outbreak in the multi-host system. The probability of disease extinction depends on the time and the population into which infection is introduced and reflects the seasonality inherent in the system. Some of the most sensitive parameters to model outcomes include wild bird recovery and environmental transmission. We find that migratory wild birds can drive infection numbers in other populations even when transmission parameters for those populations are low, and that environmental transmission can be a significant driver of infections.

Established populations of Ixodes silvanus (Acari: Ixodidae) in the Chaco Serrano, Argentina.

The aim of the study was to report the occurrence of Ixodes silvanus outside its distribution range, in the Chaco Serrano vegetation unit of the Chaco Phytogeographic Province, central Argentina. Ticks were collected from vegetation and on birds between November 2021 and December 2023. A possible seasonal activity was observed in the immature stages of I. silvanus, with larvae in autumn-winter and nymphs in spring-summer, consistent with a behavioral diapause. A total of 937 ticks were identified as I. silvanus and confirmed molecularly, 741 host-seeking and 196 parasitizing 49 passerine birds (of 9 species, 6 genera and 5 families). All host-seeking ticks were found in leaf litter in forests dominated by the invasive tree Ligustrum lucidum, suggesting a possible link between environmental changes and the establishment of I. silvanus in this region. The prevalence of I. silvanus on birds was 27.4%, with significant participation of the Turdus genus and new host associations documented. The findings suggest that I. silvanus may be expanding its range, potentially facilitated by environmental modifications, the movement of austral migratory birds (Turdus nigriceps, Synallaxis frontalis and Zonotrichia capensis), and the range expansion of other bird species (Turdus amaurochalinus, Turdus chiguanco and Turdus rufiventris). Therefore, I. silvanus may represent a biological invasion and a potential threat to wild bird populations as a vector of pathogenic microorganisms. Future studies are required to determine the implications this could have.