Bird Mortality Research Articles

High number of HPAI H5 virus infections and antibodies in wild carnivores in the Netherlands, 2020–2022

ABSTRACT In October 2020, a new lineage of a clade 2.3.4.4b HPAI virus of the H5 subtype emerged in Europe, resulting in the largest global outbreak of HPAI to date, with unprecedented mortality in wild birds and poultry. The virus appears to have become enzootic in birds, continuously yielding novel HPAI virus variants. The recently increased abundance of infected birds worldwide increases the probability of bird–mammal contact, particularly in wild carnivores. Here, we performed molecular and serological screening of over 500 dead wild carnivores and sequencing of RNA positive materials. We show virological evidence for HPAI H5 virus infection in 0.8%, 1.4%, and 9.9% of animals tested in 2020, 2021, and 2022 respectively, with the highest proportion of positives in foxes, polecats and stone martens. We obtained near full genomes of 7 viruses and detected PB2 amino acid substitutions known to play a role in mammalian adaptation in three sequences. Infections were also found in without neurological signs or mortality. Serological evidence for infection was detected in 20% of the study population. These findings suggests that a high proportion of wild carnivores is infected but undetected in current surveillance programmes. We recommend increased surveillance in susceptible mammals, irrespective of neurological signs or encephalitis.

THE PHARMACOKINETICS AND PHARMACODYNAMICS OF ORAL PONAZURIL IN THE TREATMENT OF SYSTEMIC ISOSPOROSIS IN PASSERINE BIRDS.

Systemic isosporosis, previously atoxoplasmosis, is a significant cause of mortality in juvenile passerine birds. Recommended treatment regimens are empiric and vary in efficacy. The goal of this study was to determine the pharmacokinetics and pharmacodynamics of ponazuril for treatment of systemic isosporosis. Ponazuril, diluted with water to create an oral suspension (50 mg/ml), was administered (100 mg/kg) to 72 European starlings (Sturnus vulgaris) by a single dose via direct oral gavage (n = 24), a single dose injected into superworm larvae (Zophobas morio; n = 24), or a daily dose mixed with commercial dog food to top-dress feed for 5 d (n = 24). Peak plasma concentrations were 5.84, 2.46, and 9.13 µg/ml for the direct gavage, injected larvae, and top-dressed feed groups, respectively. With repeated dosing, mean plasma concentrations from the top-dressed feed group were maintained between 8.12 to 13.11 µg/ml. Results suggested ponazuril at a dosage of 100 mg/kg administered via direct gavage or top-dressed feed, but not via injected larvae, would exceed the concentrations needed to inhibit merogony of other apicomplexan parasites in cell culture (5 µg/ml). To assess the pharmacodynamics of this dose, seven passerine birds, red-vented bulbuls (Pycnonotus cafer; n = 2), blue-grey tanager (Thraupis episcopus; n = 1), and red-capped cardinals (Paroaria gularis; n = 4), were identified as shedders of systemic Isospora spp. via fecal qPCR. Birds were then treated with ponazuril (100 mg/kg) daily on top-dressed feed for 14 d. Fecal shedding was assessed via qPCR for 6 wk from the initiation of treatment. Treatment was associated with reduction in proportions of fecal shedding during the treatment period and the week following treatment, but shedding resumed in all birds by the end of sampling. Results support that treatment of breeding birds with 100 mg/kg ponazuril could reduce the shedding of active oocysts and decrease risk of clinical infection in susceptible juveniles.

Reconstruction of the molecular evolution of Usutu virus in Germany: Insights into virus emersion and circulation.

Usutu virus (USUV) is a mosquito-borne flavivirus that is widely distributed in southern and central Europe. The zoonotic virus circulates primarily between birds and mosquitoes, can, however, in rare cases infect other mammals including humans. In the past, USUV has been repeatedly associated with mass mortalities in birds, primarily blackbirds and owls. Birds commonly succumb either due to the peracute nature of the infection or due to severe encephalitis. In Germany, USUV has spread rapidly since its first detection in 2010 in mosquitoes under the presence of susceptible host and vector species. Nonetheless, there is to date limited access to whole genome sequences resulting in the absence of in-depth phylogenetic and phylodynamic analyses. In this study, 118 wild and captive birds were sequenced using a nanopore sequencing platform with prior target enrichment via amplicons. Due to the high abundancy of Europe 3 and Africa 3 in Germany an ample quantity of associated whole genome sequences was generated and the most recent common ancestor could be determined for each lineage. The corresponding clock phylogeny revealed an introduction of USUV Europe 3 and Africa 3 into Germany three years prior to their first isolation in the avifauna in 2011 and 2014, respectively. Based on the clustering and temporal history of the lineages, evidence exists for the genetic evolution of USUV within Germany as well as new introductions thereof into the country.

Modeling long-distance airborne transmission of highly pathogenic avian influenza carried by dust particles

Highly pathogenic avian influenza (HPAI) is continuously causing significant economic losses with massive poultry depopulations. Airborne transmission of HPAI was suspected, as initial bird mortalities were reported near air inlets of poultry houses. In addition, infected farms were distant, indicating that the viruses carried by dust particles might help the viruses travel for long distances in the environment. The objective of this study focused on simulating the airborne transmission of HPAI by using computational modeling to assess the risk of airborne and deposited avian influenza (AI) carried by poultry-litter dust particles. The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) modeling was used in this study. Data from 168 infected cases in the Mid-Western area of U.S. were obtained from the Animal and Plant Health Inspection Service (APHIS) and Watt Poultry. The concentration simulation modeling was performed to estimate the airborne and deposited AI concentration carried by PM2.5 dust particles. Results showed that concentrations of airborne AI, deposited AI, and combined AI transmitted to other farms in a day were lower than the minimal infective dose for poultry. In most of the scenarios, the predicted probability of infection showed that Iowa-infected farms and turkey poultry houses had the highest infection probability. The findings may provide an understanding of the risk of airborne HPAI virus carried by dust particles and suggest the factors that influence long-distance airborne transmission.

Effects of oleanolic acid on acute liver injury triggered by lipopolysaccharide in broiler chickens

ABSTRACT 1. Infectious injury caused by lipopolysaccharide (LPS), a metabolite of gram-negative bacteria, can induce stress responses in animals and is a significant cause of morbidity and mortality in young birds. The purpose of this study was to investigate the effects of dietary supplementation with oleanolic acid (OA) on acute liver injury in broiler chickens challenged with LPS. 2. In total, 120 broiler chickens were randomly divided into six groups and fed a basal diet containing 0, 50, 100, or 200 mg/kg OA or 100 mg/kg aureomycin. On d 15, broiler chickens were injected with either LPS or an equivalent volume of normal saline. Six hours after LPS injection, two broiler chicks were randomly selected for sampling in each replicate. 3. The results indicated that dietary aureomycin was ineffective in alleviating LSP-associated liver injury, but protected broiler chickens from LPS-induced liver damage. This promoted a significant reduction in the levels of malondialdehyde and an increase in the levels of superoxide dismutase in liver. In addition, OA was found to cause significant reductions in the relative expression of IL-1β, IL-6, and TNF-α in broiler liver tissues, whereas the relative expression of IL-10 was significantly increased. 4. In conclusion, oleanolic acid can alleviate oxidative stress and injury in the livers of broiler chickens induced by lipopolysaccharide. Consequently, oleanolic acid has potential utility as a novel anti-inflammatory and antioxidant feed additive.

Highly Pathogenic Avian Influenza (HPAI) strongly impacts wild birds in Peru

The recent panzootic of Highly Pathogenic Avian Influenza (HPAI) A (H5N1) has affected hundreds of thousands of wild birds around the world. Here, we analyze the outcomes of the first H5N1 outbreak in wild birds of Peruvian protected areas. The first detection of H5N1 was confirmed in dead Peruvian pelicans (Pelecanus thagus) on 13 November 2022; the outbreak then rapidly spread to diverse areas along the Peruvian coast. By mid-March 2023, the species affected and number of dead individuals found was alarming: we found at least 100,485 wild birds belonging to 24 species (some of them threatened), which died due to this virus. The number of bird species and individuals affected by this disease in Peru is of conservation concern due to the severe effect of this virus on these populations and the ecosystem services they provide. This emerging pathogen killed, for instance, around 20 % of the pelican population inhabiting marine protected areas in Peru. We call on authorities and conservation managers in South America to be alert and implement actions such as rapid removal of infected carcasses and epidemiological surveillance to limit the spread of this virus and its consequent impact on wildlife. We must prevent this pathogen spreading to other regions in South America and Antarctica, where many potentially susceptible species live and need to be preserved. Since this emerging pathogen has produced high bird mortality worldwide, it should be addressed as a new threat to the survival of several bird species around the world.

A Comparative Study on Two Infection Models of Colibacillosis in Broilers: Clinical Features, Pathogenesis, and Response to Therapy.

Knowledge on the characteristics of different infection models of avian colibacillosis is mandatory for performing reliable experimental studies. This study compares the characteristics of two infection models of colibacillosis (by intratracheal and subcutaneous routes) in broilers. Broilers (125), 35 days old, were randomly allocated to four experimental (n = 20) and three control (n = 15) groups: 1) negative control; 2) intratracheal infection control; 3) subcutaneous infection control; 4) intratracheal infection (IT); 5) intratracheal infection with florfenicol administration (ITF); 6) subcutaneous infection (SC); and 7) subcutaneous infection with florfenicol administration (SCF). Clinical signs and mortalities were recorded, and gross examination of carcasses was performed. On days 3 and 5 postchallenge (PC), 5 birds/group were euthanatized. Despite similar onset and type of clinical signs and mortality of birds in the IT and SC groups, especially on early days PC, birds in the SC group had lower body weight than IT birds. Lung injuries were more prominent in the IT group than the SC group. Birds of the SC group showed cellulitis and severely injured kidneys in contrast to the IT group. On day 3 PC, the number of positive heart blood samples for bacterial growth in the ITF group was half that of the IT group, whereas SC and SCF birds had similar positive numbers. Infection by the subcutaneous route results in more severe disease. The intratracheal route produces results more similar to colibacillosis under field conditions with regard to clinical signs, pathogenesis, and response to therapy, albeit it is more difficult to perform than a subcutaneous challenge.

Bat mortality in wind farms of southern Europe: temporal patterns and implications in the current context of climate change

The expansion of renewable energy production, especially wind power, is one of the cornerstones of our strategy for mitigating climate change. However, there is growing concern about the impacts of this energy source on biodiversity. In particular, very little is known about the impact on groups of fauna such as bats, which are especially sensitive to environmental changes. We investigated the temporal patterns of bat fatalities in wind farms in the province of Cádiz, in the south of the Iberian Peninsula. An eleven-year data set (2009–2019) from a surveillance program of bird and bat mortality in wind farms was analysed. A total of 2,858 fatalities concerning 10 bat genera were reported, although more than 90% of the affected animals were individuals of the genera Pipistrellus, Eptesicus and Nyctalus. Bat mortality occurred mainly during the summer and autumn, especially in August. However, species such as the genus Pipistrellus, present collisions throughout the year, including all winter months in the case of the genus Pipistrellus. The probability of mortality was positively correlated with the maximum daily temperature. According to the model prediction, the probability of fatality begins to increase slightly from 20 °C and then rises sharply when the temperature exceeds 30 °C, that can be interpreted as a consequence of increasing bat activity at local scale. According to the regional projections of global climate models, an increase in maximum temperatures and the arrival of milder winters may lead to an increase in the annual mortality of bats in wind farms in the coming decades.

Bird scaring lines reduce seabird mortality in mid-water and bottom trawlers in Argentina

Abstract Seabird bycatch in fisheries, and the development of effective mitigation to minimize this, have been subject to increasing research attention over the past three to four decades. Trawl fisheries represent a particular challenge, as bird mortalities (especially highly threatened albatrosses and large petrels, Procellariforms) occur primarily through difficult-to-detect collisions with warp and net monitoring cables. Effectiveness of bird-scaring lines (BSLs) as a mitigation measure can be fleet-specific, and studies relating specifically to reducing collisions with the net monitoring cable are rare. To support improved assessment and mitigation of seabird bycatch in trawl fisheries, we studied the mortality associated with mid-water and bottom factory trawl vessels along the southern tip of the Argentine Patagonian shelf, across 2144 trawls from 2012 to 2019, with three specific objectives: (i) inform improved bycatch management in this (and other) trawl fisheries by analysing differences in seabird collision rates and outcomes between net monitoring and warp cables, as well as the effect of mitigation measures in reducing collisions; (ii) explore the effects of key fishing operation variables on seabird impact outcomes; and (iii) estimate the annual seabird mortality in the study fleet. We tested the efficacy of BSLs as a mitigation measure to reduce seabird mortality, on warps and net monitoring cables. Our results show that seabird mortality increases in the presence of a net monitoring cable. Our estimation of fishery-wide mortality without the use of BSLs includes 108 [31–186] Southern royal albatross (Diomedea epomophora) and 279 [108–465] Black-browed albatross (Thalassarche melanophris) killed annually by the collisions with the net monitoring cable. We demonstrate the efficacy of BSLs in reducing the number of collisions and in combination with no discarding of fishes, seabird interactions fell to c. zero. Our study builds the case for better bycatch data collection in trawl fisheries, the strong influence of discarding, and the feasibility of simple mitigation measures to reduce seabird bycatch, including on the net monitoring cable.

First molecular detection of avian polyomavirus from captive psittacine birds in Bangladesh, together with confirmation of beak and feather disease virus co-infection.

Avian polyomavirus (APV) is an emerging pathogen in many parts of the world responsible for causing significant mortality in captive psittacine birds. The virus spreads slowly, and transboundary movement of birds is one of the potential risk factors for the virus introduction in the naïve population. Bangladesh allows the import of birds, however there is currently no surveillance to screen for APV. Since we confirmed beak and feather disease virus (BFDV) infection in the captive population in our earlier investigation, we hypothesized that APV may also be circulating in Bangladesh. Feather samples were collected from 100 birds (90 psittacine and 10 non-psittacine). The polymerase chain reaction (PCR) was used to detect viral DNA together with sequencing and phylogenetic analysis. This first pilot study confirmed the presence (7%, 7/100) of APV in captive psittacine birds of Bangladesh and almost half (4%, 4/100) of the APV positive birds had the BFDV co-infection. All the PCR-positive birds were asymptomatic and found in live bird markets (LBMs). No significant variation was observed in the detection rate considering species (P = 0.94), age (P = 0.39) or sex (P = 0.55) of birds. According to the results of the phylogenetic study, the APV isolates found in Bangladesh appear to be unrelated to isolates from other geographical areas. These findings provide an evidence of APV circulating in Bangladesh, with or without the co-infection of BFDV. Additional studies are needed to investigate the occurrence of APV/BFDV co-infection in the larger population of Bangladesh and in countries where transboundary bird interaction with Bangladesh may be possible.

Economic losses due to Newcastle disease in layers in subtropical India

Newcastle disease (ND) is a highly contagious viral disease of birds causing immense direct and indirect losses to the poultry industry. Various studies conducted across the world suggested that ND has been creating havoc in the poultry industry. Over the past decade, India has been reporting cases of ND outbreaks every year. Therefore, a retrospective study was conducted to estimate the losses due to ND and identify the factors influencing those losses. The primary data was obtained directly from farmers employing multistage purposive random sampling. A modified methodology was employed to provide an aggregate figure accounting for the approximate losses due to ND over the period of 72 weeks of the commercial layers’ life cycle. The results of the study indicated that the losses due to morbidity were much higher compared to those due to mortality in ND-infected birds. The major factors influencing ND losses on the farms were drop in egg production, mortality of birds due to ND, duration of ND infection, reduction in feed intake, age at which birds get infected with ND, and experience of poultry farmers in the poultry business.

Marine bird mass mortality events as an indicator of the impacts of ocean warming

The frequency and severity of marine heatwaves (MHWs), an emergent property of global warming, has led to large-scale disruptions to marine ecosystems. As upper trophic species, marine birds reflect shifts in trophic structure and stability; therefore, a sharp increase in marine bird mortality is a clear signal of ecosystem impact. In this study, we analyzed 29 yr (1993-2021) of beached bird monitoring data (~90000 surveys) to identify marine bird mortality events throughout the Northeast Pacific and Alaska, USA, and examined linkages to ocean-climate variability. Mortality events were documented throughout the study period, but massive events (>500 km in extent, >10 carcasses km-1) occurred infrequently (n = 5), with an unprecedented sequence from 2014-2019. Event characteristics, including encounter rate (carcasses km-1), duration, and spatial extent, were positively related to prior-year averaged sea surface temperature anomaly, with event magnitude (product of encounter rate, extent, and duration) displaying a step-like transition, increasing 5-fold between +0°C and +1°C above baseline (1981-2010) temperatures. Mortality events occurred more frequently following MHWs, and a common sequence of mortality events (at 1-6 and 10-16 mo after heatwave onset) was observed in the California Current large marine ecosystem following 3 prolonged MHW events. Following the second wave of mortality at 10-16 mo after MHW onset, a consistent 16 mo period of depressed carcass encounter rates ensued. Given continued global warming, our results point to more frequent large-scale mortality events and the potential for a new lower carrying capacity for marine birds in the Northeast Pacific.

Poultry health constraints in smallholder village poultry systems in Northern Ghana and Central Tanzania.

Smallholder poultry production is a major contributor to food security and rural livelihoods in low-and middle-income countries. However, infectious diseases limit improvements to smallholder poultry production and performance of the sector in general. Infectious diseases of poultry, especially viral diseases, have major impacts on the health and productivity of flocks and account for significant morbidities and mortalities of birds each year. This study utilized participatory epidemiology approaches to better understand the poultry health constraints and challenges faced by smallholder poultry producers in village poultry systems in Northern Ghana and Central Tanzania. The results show dominance of small-scale semi-intensive and extensive scavenging poultry production systems in the study areas. Newcastle disease ranked as the highest cause of morbidity and mortality in chickens in the two countries. The disease occurred mainly during the months coinciding with the dry season in both countries. Other health challenges among poultry flocks included worm infestation, fowl pox, coryza, and coccidiosis. Producers, especially in rural locations, had poor access to veterinary services and critical inputs necessary for poultry production. In the Northern region of Ghana, producers lacked definitive diagnoses for sick poultry due to a shortage of veterinary personnel and diagnostic laboratories. These challenges point to the need for increased investment in poultry disease control and prevention programs, particularly in rural areas. Interventions focused on expansion of veterinary and agricultural extension services and diagnostic laboratory capacity in rural areas and increased gender-sensitive training to enhance smallholder knowledge in poultry husbandry and disease prevention measures will support the development of the smallholder village poultry systems. Tapping into the diverse genetic reservoir of local chicken ecotypes with enhanced resistance to Newcastle disease through genomic selection, coupled with models for enhancing ND vaccination supply and use in the rural areas are potential future avenues for addressing ND constraints to production.

Highly pathogenic avian influenza A (H5N1) virus infections in wild carnivores connected to mass mortalities of pheasants in Finland.

Highly pathogenic avian influenza (HPAI) has caused widespread mortality in both wild and domestic birds in Europe during 2020-2022. Virus types H5N8 and H5N1 have dominated the epidemic. Isolated spill-over infections in mammals started to emerge as the epidemic continued. In autumn 2021, HPAI H5N1 caused a series of mass mortality events in farmed and released pheasants (Phasianus colchicus) in a restricted area in southern Finland. Later, in the same area, an otter (Lutra lutra), two red foxes (Vulpes vulpes) and a lynx (Lynx lynx) were found moribund or dead and infected with H5N1 HPAI virus. Phylogenetically, H5N1 strains from pheasants and mammals clustered together. Molecular analyses of the four mammalian virus strains revealed mutations in the PB2 gene segment (PB2-E627K and PB2-D701N) that are known to facilitate viral replication in mammals. This study revealed that avian influenza cases in mammals were spatially and temporally connected with avian mass mortalities suggesting increased infection pressure from birds to mammals.

Prevalence and Management of Endoparasitic Worm load in Ostriches of Different Captive Conditions Housed in Punjab, Pakistan

Ostrich farming has attained a status of a fast-growing agribusiness in the livestock industry due to the wide range of associated benefits attached to it. This study was designed to assess the prevalence of endoparasites in this economically important bird as well as their treatment to provide better guidelines for successful ostrich farming. The study involved 385 feacal samples of ostriches taken from 55 commercial farms and captive sites Punjab during the period of January 2020 to December 2020. The relevant data and samples were collected from 15 districts of Punjab. Feacal samples were tested against gastrointestinal worm load by using floatation and sedimentation techniques. Ostriches of 11 commercial farms and Lahore Zoo, Jallo Wildlife Park Lahore, UVAS Ostrich farm Pattoki and Bahawalnagar Wildlife Park were found to harbor protozoan parasites such as Eimeria spp. Balantidium coli, and Amoeboid cyst. It was noteworthy that the use of herbal dewormers showed much better results than chemical anthelmintics. Similarly, those wildlife parks where ostriches were given a natural environment showed negative results for endoparasites. At some farms combination of chemical and herbal anthelmintics was also used. The absence of a reliable nutritional management system caused the mortality of ostriches at 40 farms due to gastric problems and choking. The mortality rate at the age of 2-4 months was 73% while mortality of adult birds from 1-7 years was 27%. Among selected farms, 50% of ostriches were facing lameness, leg deformities, and retarded growth due to improper space, a congested environment, and poor feeding systems. Lastly, more research is needed to make this agribusiness flourished.

Investigating the Genetic Diversity of H5 Avian Influenza Viruses in the United Kingdom from 2020-2022.

Since 2020, the United Kingdom and Europe have experienced annual epizootics of high-pathogenicity avian influenza virus (HPAIV). The first epizootic, during the autumn/winter of 2020-2021, involved six H5Nx subtypes, although H5N8 HPAIV dominated in the United Kingdom. While genetic assessments of the H5N8 HPAIVs within the United Kingdom demonstrated relative homogeneity, there was a background of other genotypes circulating at a lower degree with different neuraminidase and internal genes. Following a small number of detections of H5N1 in wild birds over the summer of 2021, the autumn/winter of 2021-2022 saw another European H5 HPAIV epizootic that dwarfed the prior epizootic. This second epizootic was dominated almost exclusively by H5N1 HPAIV, although six distinct genotypes were defined. We have used genetic analysis to evaluate the emergence of different genotypes and proposed reassortment events that have been observed. The existing data suggest that the H5N1 viruses circulating in Europe during late 2020 continued to circulate in wild birds throughout 2021, with minimal adaptation, but then went on to reassort with AIVs in the wild bird population. We have undertaken an in-depth genetic assessment of H5 HPAIVs detected in the United Kingdom over two winter seasons and demonstrate the utility of in-depth genetic analyses in defining the diversity of H5 HPAIVs circulating in avian species, the potential for zoonotic risk, and whether incidents of lateral spread can be defined over independent incursions of infections from wild birds. This provides key supporting data for mitigation activities. IMPORTANCE High-pathogenicity avian influenza virus (HPAIV) outbreaks devastate avian species across all sectors, having both economic and ecological impacts through mortalities in poultry and wild birds, respectively. These viruses can also represent a significant zoonotic risk. Since 2020, the United Kingdom has experienced two successive outbreaks of H5 HPAIV. While H5N8 HPAIV was predominant during the 2020-2021 outbreak, other H5 subtypes were also detected. The following year, there was a shift in the subtype dominance to H5N1 HPAIV, but multiple H5N1 genotypes were detected. Through the thorough utilization of whole-genome sequencing, it was possible to track and characterize the genetic evolution of these H5 HPAIVs in United Kingdom poultry and wild birds. This enabled us to assess the risk posed by these viruses at the poultry-wild bird and the avian-human interfaces and to investigate the potential lateral spread between infected premises, a key factor in understanding the threat to the commercial sector.

Lower survival of hybrid grosbeaks, but not towhees, suggests a molt divide disfavors hybrids.

Although avian hybrid zones in the Great Plains have been studied for almost 70 years, we know surprisingly little about the fitness costs to hybrids that keep these zones narrow. We compare age ratios in grosbeaks (Pheucticus ludovicianus and P. melanocephalus) and towhees (Pipilo erythropthalums and P. maculatus), two species pairs that differ in their life-histories and molt schedules, to evaluate survival between hybrids and parentals. We then contrast molt and migratory divides as possible sources of selection against hybrids. Hybrid grosbeaks had 27-33% lower survival relative to their parentals, whereas hybrid towhees had survival rates similar to parentals. Age ratio data for hybrid grosbeaks suggest high mortality in older birds, as expected if selection operates after the first year of life. This pattern is consistent with parental species of grosbeaks having contrasting molt schedules relative to migration, suggesting high mortality costs to hybrids driven by molt biology, which are expressed later in life. Contrasts in molt schedules are absent in towhees. While migratory divides may exist for towhees and grosbeaks, the low adult survival of hybrid grosbeaks suggest that molt may be an important and underappreciated source of selection maintaining this and other narrow avian hybrid zones.

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This review examines the reported impacts of three major linear infrastructure developments, namely railways, roads and power lines on avifauna. These infrastructures are proliferating worldwide posing serious threats to wildlife including avifauna. The major impacts involved with linear infrastructures are habitat degradation, fragmentation, direct mortality by collision and electrocution. The factors affecting collision mortality can be divided into intrinsic and extrinsic factors. The intrinsic factors include species morphology and species behavior whereas the extrinsic factors are the external factors such as weather, landscape features and the technical aspects of the infrastructure. Power lines affect a large number of birds, killing more than one billion birds globally each year. Studies suggest the implementation of anti-collision devices such as wire markers; flight diverters and physical barriers like trees, diversion poles or noise barriers are effective mitigation measures to reduce bird mortality due to the linear infrastructures. Therefore, understanding the overall impact of linear infrastructures is crucial for effectively managing their impacts on avifauna and helping make future developments less destructive and more sustainable.

Predicted reduction in transmission from deployment of ivermectin-treated birdfeeders for local control of West Nile virus

Ivermectin (IVM)-treated birds provide the potential for targeted control of Culex mosquitoes to reduce West Nile virus (WNV) transmission. Ingestion of IVM increases mosquito mortality, which could reduce WNV transmission from birds to humans and in enzootic maintenance cycles affecting predominantly bird-feeding mosquitoes and from birds to humans. This strategy might also provide an alternative method for WNV control that is less hampered by insecticide resistance and the logistics of large-scale pesticide applications. Through a combination of field studies and modeling, we assessed the feasibility and impact of deploying IVM-treated birdfeed in residential neighborhoods to reduce WNV transmission. We first tracked 105 birds using radio telemetry and radio frequency identification to monitor their feeder usage and locations of nocturnal roosts in relation to five feeder sites in a neighborhood in Fort Collins, Colorado. Using these results, we then modified a compartmental model of WNV transmission to account for the impact of IVM on mosquito mortality and spatial movement of birds and mosquitoes on the neighborhood level. We found that, while the number of treated lots in a neighborhood strongly influenced the total transmission potential, the arrangement of treated lots in a neighborhood had little effect. Increasing the proportion of treated birds, regardless of the WNV competency status, resulted in a larger reduction in infection dynamics than only treating competent birds. Taken together, model results indicate that deployment of IVM-treated feeders could reduce local transmission throughout the WNV season, including reducing the enzootic transmission prior to the onset of human infections, with high spatial coverage and rates of IVM-induced mortality in mosquitoes. To improve predictions, more work is needed to refine estimates of daily mosquito movement in urban areas and rates of IVM-induced mortality. Our results can guide future field trials of this control strategy.

Wind turbine power and land cover effects on cumulative bat deaths

Wind turbines (WT) cause bird and bat mortalities which depend on the WT and landscape features. The effects of WT features and environmental variables at different spatial scales associated to bat deaths in a mountainous and forested area in Thrace, NE Greece were investigated. Initially, we sought to quantify the most lethal WT characteristic between tower height, rotor diameter and power. The scale of interaction distance between bat deaths and the land cover characteristics surrounding the WTs was quantified. A statistical model was trained and validated against bat deaths and WT, land cover, and topography features. Variance partitioning between bat deaths and the explanatory covariates was conducted. The trained model was used to predict bat deaths attributed to existing and future wind farm development in the region. Results indicated that the optimal interaction distance between WT and surrounding land cover was 5 km, the larger distance than the ones examined. WT power, natural land cover type and distance from water explained 40 %, 15 % and 11 % respectively of the total variance in bat deaths by WTs. The model predicted that operating but not surveyed WTs comprise of 377.8 % and licensed but not operating yet will contribute to 210.2 % additional deaths than the ones recorded. Results indicate that among all WT features and land cover characteristics, wind turbine power is the most significant factor associated to bat deaths. In addition, WTs located within 5 km buffer comprised of natural land cover types have substantial higher deaths. More WT power will result in more deaths. Wind turbines should not be licensed in areas where natural land cover at a radius of 5 km exceeds 50 %. These results are discussed in the climate-land use-biodiversity-energy nexus.