Pigeon Populations Research Articles

Urban Pigeons as Reservoirs of Critical Pathogens: Improved protocol for sequencing pigeon faeces in disease monitoring

The spread of pathogens by animals is a serious issue around the world that causes a severe threat to human health. Feral pigeons (Columba livia forma domestica) that live in urban areas are zoonotic carriers of various pathogens that can be transmitted to humans by faecal contamination. This study aimed to detect the presence of bacterial, viral, and specifically fungal pathogens in pigeon faeces based on the World Health Organization's (WHO) priority pathogen list published in 2022. Fresh faecal samples were collected at Uppsala, Central Station, and Svandammen, the pigeons' most relevant gathering spots and feeding sites. Genomic DNA was directly extracted from these samples, and ScilifeLab performed High throughput sequencing through Oxford Nanopore Technologies(ONT) (PromethION). Metagenomic analysis revealed that most of the critically prioritized viral and bacterial pathogens listed by WHO were present in pigeon faeces. Regarding fungal pathogens, which were the main objective of this study, samples from both studied locations contained all critical, high and, medium-important fungal pathogens published in the WHO list, such as Aspergillus fumigatus, Candida albicans, Candida auris, Cryptococcus neoformans, Nakaseomyces glabratus, Candida tropicalis, and Cryptococcus gattii. These fungal pathogens pose the risk of invasive fungal diseases and severe infections in low-immunity individuals and vulnerable populations. The findings indicate the importance of conducting further research to comprehensively understand potential exposure to feral pigeons. Furthermore, keeping pigeons away from sensitive areas, such as hospitals, and implementing measures to control pigeon populations can significantly decrease the spread of pathogens.

Comparative Analysis of Newcastle Disease Seroprevalence in Different Breeds of Pigeon Populations in Chattogram Bangladesh

This study was performed to determine the antibody against Newcastle disease and serum protein level in pigeons of Chattogram, Bangladesh. The results were evaluated in pigeons of different groups of age, sex, and breed by applying the hemagglutination inhibition (HI) test. A total of 90 pigeons were selected for this research. Antibody titer against Newcastle Disease virus was analyzed according to the different age groups, sex, breeds and clinical signs of ND infection of pigeons by X2 test. Incase of less than 6 month age pigeons 73% (n=22) were HI titer positive whereas more than 6 months but less than 1 year 56% (n=32) were HI negative. There was no significant variation among different sex. In both male and female pigeon groups, the percentage of HI titer-positive pigeons in females and males was 51.7% and 57.4% respectively. There was significant variation among the different breeds and equal percentages of HI titer positive and negative pigeons were found in Giribaj and local breeds whereas 100% were found in King and Owl breeds and 80% were found in the Siraji breed. There was significant variation among NDV-infected and non-infected pigeons and equal percentage of HI titer negative and positive pigeons were found in ND non- infected, whereas (80.8%) were found in ND infected pigeons. A paired test was done between HI titer and total serum protein. There was a significant (t<0.0) difference among the group. In the case of HI titer mean was about 23 titer and the standard error was 0.28. In the case of total serum protein mean was 4.45 and the standard error was 0.19.

Comparative Analysis of Newcastle Disease Seroprevalence in Different Breeds of Pigeon Populations in Chattogram, Bangladesh

This study was performed to determine the antibody against Newcastle disease and serum protein level in pigeons of Chattogram, Bangladesh. The results were evaluated in pigeons of different groups of age, sex, and breed by applying the hemagglutination inhibition (HI) test. A total of 90 pigeons were selected for this research. Antibody titer against Newcastle Disease virus was analyzed according to the different age groups, sex, breeds, and clinical signs of ND infection of pigeons by X2 test. In the case of fewer than 6 months of age pigeons, 73% (n=22) were HI titer positive whereas more than 6 months but less than 1 year 56% (n=32) were HI negative. There was no significant variation among the different sexes. In both male and female pigeon groups, the percentage of HI titer-positive pigeons in females and males was 51.7% and 57.4% respectively. There was significant variation among the different breeds and equal percentages of HI titer positive and negative pigeons were found in Giribaj and local breeds whereas 100% were found in King and Owl breeds and 80% were found in the Siraji breeds. There was significant variation among NDV-infected and non-infected pigeons and an equal percentage of HI titer negative and positive pigeons were found in ND non-infected, whereas (80.8%) were found in ND-infected pigeons. A paired test was done between HI titer and total serum protein. There was a significant (t<0.0) difference among the groups. In the case of HI titer mean was about 23 titer and the standard error was 0.28. In the case of total serum protein mean was 4.45 and the standard error was 0.19.

Constitutive innate immune defenses in relation to urbanization and population density in an urban bird, the feral pigeon Columba livia domestica.

Urbanization processes modulate the immunological challenges faced by animals. Urban habitat transformations reshape pathogen diversity and abundance, while high population density-common in urban exploiter species-promotes disease transmission. Responses to urbanization may include adaptive adjustments of constitutive innate immune defenses (e.g. complement system and natural antibodies [NAbs]), which serve as first-line protection against infections. Here, we investigated associations of habitat urbanization and host population density with complement and NAbs in an urban bird, the feral pigeon Columba livia domestica. To do so, we employed the hemolysis-hemagglutination assay to analyze nearly 200 plasma samples collected across urbanization and pigeon population density gradients in five major cities in Poland. We found a negative association between urbanization score and hemagglutination (i.e. NAbs activity), but not hemolysis (i.e. complement activity), indicating either immunosuppression or adaptive downregulation of this immune defense in highly transformed urban landscape. Population density was not significantly related to either immune parameter, providing no evidence for density-dependent modulation of immune defenses. At the same time, there was a negative association of hemolysis with condition (scaled mass index), suggesting resource allocation trade-offs or contrasting effects of the urban environment on immune defenses and body condition. The results demonstrate that habitat structure can be an important factor shaping the immune defenses of the feral pigeon, although these associations were not mediated by variation in population density. Our study highlights the complexity of the links between immune defenses in wildlife and urbanization and reinforces the need for comprehensive ecoimmunological studies on urban animals.

MtDNA genetic diversity and phylogeographic insights into giant domestic pigeon (Columba livia domestica) breeds: connections between Central Europe and the Middle East

Humans have selectively bred domestic pigeons (Columba livia domestica) to create breeds with a diversity of shapes, colors and other attributes. Since Darwin, the domestic pigeon has always been a popular model species for scientific research because of its richness of form, colouration and behaviour. It is believed that the world's squab pigeon industry uses breeds and hybrids from the Mediterranean region. An exception is the indigenous giant pigeon breeds of the Carpathian Basin, whose origin is not known. Therefore, our aims were 1) to understand the phylogenetic relationships of giant pigeons, which sheds light on the origin of Hungarian breeds and their relationship to the Mediterranean giant pigeon breed group; 2) to contribute molecular genetic data to the genealogy of 2 Iraqi pigeon breeds close to the pigeon domestication center, including the culturally important Iraqi Red Pigeon, and 3) to compare the genetic diversity of European and Middle Eastern domestic pigeon populations and to draw conclusions on the phylogenetic relationships between pigeon breeds and molecular clues to their different breeding practices of both regions. A 655-bp-long sequence of the cytochrome oxidase 1 (COI) region of the mitochondrial DNA was studied in a total of 276 pigeons (19 breeds). A total of 27 haplotypes were found, of which 22 were unique. The highest genetic diversity was found in the Carpathian Basin, and the lowest in the Iraqi region. STRUCTURE analysis revealed low structurality, K=3 was the most likely. The majority of the samples belong to the most ancient haplotype H_2=219, however the Jacobin pigeon is on a very separate evolutionary branch with a large number of mutations. None of the 19 breeds investigated in this study have been previously studied in phylogenetics, and most of these breeds have potential as squab pigeons, and have good meat forms for utilization, therefore the results of this study may also be of help to the squab pigeon industry.

Molecular characteristics and phylogenetic analysis of pigeon paramyxovirus type 1 isolates from pigeon meat farms in Shanghai (2009–2012)

The majority of pigeon paramyxovirus type 1 (PPMV-1) strains are generally non-pathogenic to chickens; however, they can induce severe illness and high mortality rates in pigeons, leading to substantial economic repercussions. The genomes of 11 PPMV-1 isolates from deceased pigeons on meat pigeon farms during passive monitoring from 2009 to 2012 were sequenced and analyzed using polymerase chain reaction and phylogenetic analysis. The complete genome lengths of 11 isolates were approximately 15,192 nucleotides, displaying a consistent gene order of 3′-NP-P-M-F-HN-L-5′. ALL isolates exhibited the characteristic motif of 112RRQKRF117 at the fusion protein cleavage site, which is characteristic of velogenic Newcastle disease virus. Moreover, multiple mutations have been identified within the functional domains of the F and HN proteins, encompassing the fusion peptide, heptad repeat region, transmembrane domains, and neutralizing epitopes. Phylogenetic analysis based on sequences of the F gene unveiled that all isolates clustered within genotype VI in class II. Further classification identified at least two distinct sub-genotypes, with seven isolates classified as sub-genotype VI.2.1.1.2.2, whereas the others were classified as sub-genotype VI.2.1.1.2.1. This study suggests that both sub-genotypes were implicated in severe disease manifestation among meat pigeons, with sub-genotype VI.2.1.1.2.2 displaying an increasing prevalence among Shanghai’s meat pigeon population since 2011. These results emphasize the value of developing pigeon-specific vaccines and molecular diagnostic tools for monitoring and proactively managing potential PPMV-1 outbreaks.

First transcriptomic insight into the working muscles of racing pigeons during a competition flight

BackgroundThe currently known homing pigeon is a result of a sharp one-sided selection for flight characteristics focused on speed, endurance, and spatial orientation. This has led to extremely well-adapted athletic phenotypes in racing birds.MethodsHere, we identify genes and pathways contributing to exercise adaptation in sport pigeons by applying next-generation transcriptome sequencing of m.pectoralis muscle samples, collected before and after a 300 km competition flight.ResultsThe analysis of differentially expressed genes pictured the central role of pathways involved in fuel selection and muscle maintenance during flight, with a set of genes, in which variations may therefore be exploited for genetic improvement of the racing pigeon population towards specific categories of competition flights.ConclusionsThe presented results are a background to understanding the genetic processes in the muscles of birds during flight and also are the starting point of further selection of genetic markers associated with racing performance in carrier pigeons.

Antimicrobial Resistance and Genomic Characterization of Salmonella Isolated from Pigeons in China

Salmonellosis is one of the important bacterial infectious diseases affecting the health of pigeons. Heretofore, the epidemiological characteristics of Salmonella in pigeon populations in China remain largely unclear. The present study investigated the antimicrobial resistance and genomic characteristics of Salmonella isolates in pigeons in different regions of China from 2022 to 2023. Thirty-two Salmonella isolates were collected and subjected to 24 different antimicrobial agents, representing nine categories. The results showed that these isolates were highly resistant to cefazolin (100%), gentamicin (100%), tobramycin (100%), and amikacin (100%). Three or more types of antimicrobial resistance were present in 90.62% of the isolates, indicating multidrug resistance. Furthermore, using whole genome sequencing technology, we analyzed the profiles of serotypes, multilocus sequence typing, virulence genes, antimicrobial resistance genes, and plasmid replicons and constructed phylogenetic genomics to determine the epidemiological correlation among these isolates. All strains belonged to Salmonella Typhimurium var. Copenhagen and exhibited five antimicrobial resistance genes and more than 150 Salmonella virulence genes. Moreover, each isolate contained both the IncFIB(S) and IncFII(S) plasmids. In addition, phylogenetic analysis showed that all isolates were very close to each other, and isolates from the same region clustered in the same branch. Overall, our findings provide the first evidence for the epidemiological characteristics of Salmonella in pigeons of China, highlighting the importance of preventing salmonellosis in pigeons.

Genetic diversity of Cryptosporidium spp., Encephalitozoon spp. and Enterocytozoon bieneusi in feral and captive pigeons in Central Europe.

Cryptosporidium spp., Enterocytozoon bieneusi and Encephalitozoon spp. are the most common protistan parasites of vertebrates. The results show that pigeon populations in Central Europe are parasitised by different species of Cryptosporidium and genotypes of microsporidia of the genera Enterocytozoon and Encephalitozoon. A total of 634 and 306 faecal samples of captive and feral pigeons (Columba livia f. domestica) from 44 locations in the Czech Republic, Slovakia and Poland were analysed for the presence of parasites by microscopy and PCR/sequence analysis of small subunit ribosomal RNA (18S rDNA), 60kDa glycoprotein (gp60) and internal transcribed spacer (ITS) of SSU rDNA. Phylogenetic analyses revealed the presence of C. meleagridis, C. baileyi, C. parvum, C. andersoni, C. muris, C. galli and C. ornithophilus, E. hellem genotype 1A and 2B, E. cuniculi genotype I and II and E. bieneusi genotype Peru 6, CHN-F1, D, Peru 8, Type IV, ZY37, E, CHN4, SCF2 and WR4. Captive pigeons were significantly more frequently parasitised with screened parasite than feral pigeons. Cryptosporidium meleagridis IIIa and a new subtype IIIl have been described, the oocysts of which are not infectious to immunodeficient mice, whereas chickens are susceptible. This investigation demonstrates that pigeons can be hosts to numerous species, genotypes and subtypes of the studied parasites. Consequently, they represent a potential source of infection for both livestock and humans.

Population size and factors influencing the distribution of the urban pigeon Columba livia f. domestica in Pamplona

The environmental and trophic conditions of cities often give rise to very large populations of urban pigeons Columba livia f. domestica, which can cause local health and heritage problems due to accumulations of their droppings. Estimating the size of pigeon populations and defining their spatial patterns of abundance are therefore crucial for effective pigeon management in built-up areas. This article estimates the abundance of pigeons in Pamplona and the factors that explain the variability of pigeon abundance at local level. The Random Forest model of abundance at a local scale of 0.25 km2 cells had very high explanatory power, although its predictive power decreased due to this species’ gregariousness. Abundance decreased with increasing distance from the city centre, and from historic buildings and large parks, but increased as the proportion of the area covered by parks and built-up areas increased. The rock pigeon population in Pamplona was estimated at 8,030 individuals (95% CI: 6,483–9,860). The estimated density of urban pigeons for Pamplona as a whole was, on average, 218 birds/km2, although this figure varied considerably between habitats and areas: the highest values were measured in urban areas with historic buildings (exceeding 600 individuals/km2; in 35.8% of the 0.25 km2 cells, more than 200 individuals were estimated). Pigeon densities fell to ca. 250 birds/km2 in urban areas lacking large parks or green spaces whether near or far from historic buildings. In the peri-urban areas (i.e. arable fields, scrub and woodland), densities decreased to around 10–50 individuals/km2. In the city of Pamplona, although the population density of urban pigeons did not reach the numbers observed in other northern Spanish cities such as Barcelona, the habitat preference patterns in urban gradients are consistent with those documented in other European regions. We identify specific urban areas for population control and recommend measures such as feeding bans and waste and facade management to make it difficult for urban pigeons to access roosting and breeding sites in buildings.

Automatic Detection of Feral Pigeons in Urban Environments Using Deep Learning.

The overpopulation of feral pigeons in Hong Kong has significantly disrupted the urban ecosystem, highlighting the urgent need for effective strategies to control their population. In general, control measures should be implemented and re-evaluated periodically following accurate estimations of the feral pigeon population in the concerned regions, which, however, is very difficult in urban environments due to the concealment and mobility of pigeons within complex building structures. With the advances in deep learning, computer vision can be a promising tool for pigeon monitoring and population estimation but has not been well investigated so far. Therefore, we propose an improved deep learning model (Swin-Mask R-CNN with SAHI) for feral pigeon detection. Our model consists of three parts. Firstly, the Swin Transformer network (STN) extracts deep feature information. Secondly, the Feature Pyramid Network (FPN) fuses multi-scale features to learn at different scales. Lastly, the model's three head branches are responsible for classification, best bounding box prediction, and segmentation. During the prediction phase, we utilize a Slicing-Aided Hyper Inference (SAHI) tool to focus on the feature information of small feral pigeon targets. Experiments were conducted on a feral pigeon dataset to evaluate model performance. The results reveal that our model achieves excellent recognition performance for feral pigeons.

The effects of urban thermal heterogeneity and feather coloration on oxidative stress and metabolism of pigeons (Columba livia)

Urbanization stands out as a significant anthropogenic factor, exerting selective pressures on ecosystems and biotic components. A notable outcome of urbanization is thermal heterogeneity where the emergence of Urban Heat Islands is characterized by elevated air and surface temperatures compared to adjacent rural areas. Investigating the influence of thermal heterogeneity on urban animals could offer insights into how temperature variations can lead to phenotypic shifts. Urban pigeons (Columba livia) serve as an excellent model for studying urban thermal effects, given the melanism variations, which are associated with the pleiotropy of the melanocortin system. To examine the development of physiological plasticity in response to urban thermal variations, we conducted a study on pigeons in Santiago, Chile, during the rainy season. We assessed the influence of habitat on physiological traits related to metabolism and antioxidant capacities, which are theoretically affected by feather coloration. Our findings reveal that variations in melanism significantly impact pigeon physiology, affecting both antioxidant capacities and the mitochondrial activity of red blood cells. It was found that higher urban temperatures, from both the current sampling month and the prior sampling month (from CRU TS dataset), were negatively and strongly associated with lower antioxidant and metabolic activities. This suggests that elevated urban temperatures likely benefit the energetic budgets of pigeon populations and mitigate the negative effects of oxidative metabolism, with differential effects depending on feather colorations.

Genome-wide association study of growth traits and validation of key mutations (MSTN c.C861T) associated with the muscle mass of meat pigeons.

Selective breeding of meat pigeons is primarily based on growth traits, especially muscle mass (MM). Identification of functional genes and molecular markers of growth and slaughter traits through a genome-wide association study (GWAS) will help to elucidate the underlying molecular mechanisms and provide a theoretical basis for the selective breeding of meat pigeons. The phenotypic data of body weight (BW) and body size (BS) of 556 meat pigeons at 52 and 80 weeks of age were collected. In total, 160 434 high-quality single nucleotide polymorphism sites were obtained by restriction site-associated DNA sequencing. The GWAS analysis revealed that MSTN, IGF2BP3 and NCAPG/LCORL were important candidate genes affecting the growth traits of meat pigeons. IGF2BP3 and NCAPG/LCORL were highly correlated to BW and BS, which are related to overall growth and development, while MSTN was associated with pectoral thickness and BW. Phenotypic association validation with the use of two meat pigeon populations found that the MSTN mutation c.C861T determines the MM. These results provide new insights into the genetic mechanisms underlying phenotypic variations of growth traits and MM in commercial meat pigeons. The identified markers and genes provide a theoretical basis for the selective breeding of meat pigeons.

Genetska analiza gradskih golubova (Columba livia) kroz markere povezane s bojom perja u općini Montería, Córdoba, Kolumbija

The species known as the domestic pigeon, scientifically Columba livia, has managed to establish itself successfully in urban environments of numerous cities around the world. This expansion has become so significant that it has triggered concerns related to its tendency to nest in human-built structures. This nesting behaviour has contributed to the deterioration of these buildings. The distinctive presence of these birds in neighbourhoods and plazas has generated a growing interest in better understanding the genetic patterns that encode their varied coloration and plumage designs. The aim of this study was to investigate the genetic variability of the population of domestic pigeons (Columba livia) in Montería, Colombia, using phenotypic markers of plumage. Random sampling was conducted between March and April 2023 on 21 flocks of pigeons within the municipality of Montería. Through urban excursions, direct observation, and photographic records, 1570 individuals were phenotypically classified. Autosomal markers encoding coloration and plumage design were studied: Checker (C), Grizzle (G), Spread (S), and Ash-Red (B). The genetic profiles of subpopulations of domestic pigeons were established using the following genetic population indices: expected heterozygosity (He), total genetic diversity (HT), diversity within populations (HS), diversity between populations (DST), coefficient of genetic diversity (GST), gene flow (Nm), and genetic distance between populations. It was found that the most common allele in the studied populations is Checker, allelic frequencies ranged from 0.315 for the Checker gene to 0.005 for the Spread marker. Total genetic diversity was moderate, and genetic differentiation between populations was low, accompanied by a high gene flow. An excess of heterozygotes was also observed, and low genetic distance values were found between populations. The results indicate limited genetic differentiation among populations, leading to the conclusion that pigeon populations in Montería are highly related.

Baseline study of the morphological and genetic characteristics of Haemoproteus parasites in wild pigeons (Columba livia) from paddy fields in Thailand.

Haemoproteus columbae is a common haemosporidian parasite of wild pigeons (Columba livia) reported worldwide. In Thailand, the wild pigeon population is increasing due to paddy field monoculture. However, there are limited reports on the presence of H. columbae in these pigeon populations. The aim of the study was to characterize H. columbae in wild pigeons. A total of 87 wild pigeons were examined using microscopic and molecular methods. Haemoproteus columbae was detected in approximately 27.6% of pigeons and their morphological characteristics were described. The partial cytochrome b (cyt b) gene sequence of H. columbae was then characterized into three common lineages (HAECOL1, COLIV03, and COQUI05). By highlighting the morphologic and genetic characteristics of H. columbae commonly found in this population of pigeons, this study provides essential regional knowledge about haemosporidian parasites that could benefit future taxonomic and phylogeographic studies.

DOES PREENING BEHAVIOR REDUCE THE PREVALENCE OF AVIAN FEATHER LICE (PHTHIRAPTERA: ISCHNOCERA)?

Animals defend themselves against parasites in many ways. Defenses, such as physiological immune responses, are capable of clearing some infections. External parasites that do not feed on blood, however, are not controlled by the physiological immune system. Instead, ectoparasites like feather-feeding lice (Phthiraptera: Ischnocera) are primarily controlled by behavioral defenses such as preening. Here we test the hypothesis that birds able to preen are capable of clearing infestations of feather lice. We experimentally manipulated preening ability in a captive population of rock pigeons (Columba livia) that were infested with identical numbers of feather lice (Columbicola columbae or Campanulotes compar or both). We then monitored the feather louse infestations for 42 wk. Birds with impaired preening remained infested throughout the experiment; in contrast, the prevalence of lice on birds that could preen normally decreased by 50%. These data indicate that it is indeed possible for birds to clear themselves of feather lice, and perhaps other ectoparasites, by preening. We note, however, that captive birds spend more time preening than wild birds, and that they are less likely to be reinfested than wild birds. Thus, additional studies are necessary to determine under what circumstances wild birds can clear themselves of ectoparasites by preening.

Proximity to anthropogenic food sources determine roosting and nesting prevalence of feral pigeons (Columba livia) in a tropical city

AbstractThe feral pigeon (Columba livia) is a globally commensal bird that can cause dis‐amenities such as soiling and is a potential vector of various diseases. Aside to limiting food as a management strategy, reducing the availability of roosting and nesting sites can help regulate feral pigeon populations. Despite their prevalence, current knowledge of their roosting and nesting preferences is lacking.Feral pigeons commonly use railway viaduct expansion gaps in Singapore for roosting and nesting. These gaps provided an ideal experimental platform to examine feral pigeon roost and nest site selection while controlling for differing cavity sizes which can significantly affect their reproductive success and site selection decisions. We also conducted an in‐situ experiment to test the efficacy of nest removal as a management option.Our nationwide surveys of 80.3 km of railway viaducts and 6048 gaps revealed that feral pigeon day roosting and nesting preferences are influenced by structural height and more importantly, their proximity to human food sources. There was a significantly higher probability of feral pigeon roosting in a gap if it had more pigeon feeding incidences in its vicinity and was higher. The probability of feral pigeon nesting in gap was higher if it was closer to a railway station, lower and further from water bodies.In our field experiment, we did not find any significant differences in the proportions of the abundances of feral pigeon to other urban commensal bird species at the gaps before and after nests were removed.Overall, our results suggest that a concerted effort to reduce anthropogenic food availability to feral pigeons is central in limiting their reproductive success and controlling their population.

Comparative pathogenicity of a genotype XXI.1.2 pigeon Newcastle disease virus isolate in pigeons and chickens

Here, we performed molecular and pathogenic characterization of a Newcastle disease virus (NDV) isolate from pigeons in Bangladesh. Molecular phylogenetic analysis based on the complete fusion gene sequences classified the three study isolates into genotype XXI (sub-genotype XXI.1.2) together with recent NDV isolates obtained from pigeons in Pakistan (2014–2018). The Bayesian Markov Chain Monte Carlo analysis revealed that the ancestor of Bangladeshi pigeon NDVs and the viruses from sub-genotype XXI.1.2 existed in the late 1990s. Pathogenicity testing using mean embryo death time pathotyped the viruses as mesogenic, while all isolates carried multiple basic amino acid residues at the fusion protein cleavage site. Experimental infection of chickens and pigeons revealed no or minimum clinical signs in chickens, while a relatively high morbidity (70%) and mortality (60%) were observed in pigeons. The infected pigeons showed extensive and systemic lesions including hemorrhagic and/or vascular changes in the conjunctiva, respiratory and digestive system and brain, and atrophy in the spleen, while only mild congestion in the lungs was noticed in the inoculated chickens. Histologically, consolidation in the lungs with collapsed alveoli and edema around the blood vessels, hemorrhages in the trachea, severe hemorrhages and congestion, focal aggregation of mononuclear cells, and single hepatocellular necrosis in the liver, severe congestion, multifocal tubular degeneration, and necrosis, as well as mononuclear cell infiltration in the renal parenchyma, encephalomalacia with severe neuronal necrosis with neuronophagia were noticed in the brain in infected pigeons. In contrast, only slight congestion was found in lungs of the infected chickens. qRT-PCR revealed the replication of the virus in both pigeons and chickens; however, higher viral RNA loads were observed in oropharyngeal and cloacal swabs, respiratory tissues, and spleen of infected pigeons than the chickens. In conclusion, genotype XXI.1.2 NDVs are circulating in the pigeon population of Bangladesh since 1990s, produce high mortality in pigeons with pneumonia, hepatocellular necrosis, renal tubular degeneration, and neuronal necrosis in pigeons, and may infect chickens without overt signs of clinical disease and are likely to shed viruses via the oral or cloacal routes.

Investigation of Trichomonas gallinae in passerines

Trichomoniasis, caused by the protozoan Trichomonas gallinae, has as main hosts birds of the Columbidae family, which have a high prevalence of the protozoan without manifesting the disease. The continuous growth of the pigeon population and its cosmopolitan nature mean that today there is a worldwide distribution of this species, being responsible for the distribution and maintenance of the prevalence of trichomoniasis in almost the entire world. The transmission of the disease may be by direct contact, or indirect, through food or water. This indirect route is the reason why such a wide range of bird orders can be infected, very different from columbids such as falconiformes, strigiformes, passerines, piciformes, psittaciformes, gruiformes, galliformes or anseriformes. Thus, the objective of this study was to evaluate the presence of T. gallinae in passerines received at a Wild Animal Screening Center. In order to carry out this study, 300 birds of the order Passerine corresponding to 23 different species were analyzed, received at the Wild Fauna Rehabilitation Center (NURFS) of the Federal University of Pelotas (UFPel), in different seasons of the year between the months of March to October 2021. Samples of swabs from the oropharynx were collected from all individuals, the material was immediately placed in a falcon tube containing Trypticase-Yeast Extract-Maltose (TYM) culture medium and sent to the Laboratory of Protozoology and Entomology (LAPEn), for incubation in a bacteriological growth greenhouse and subsequent identification of the protozoan on a slide in wet mounting under an optical microscope in a 40X objective. Wet mounting on a slide was performed in triplicate and analyzed in its entirety. Of the 300 birds evaluated in in vitro culture for T. gallinae, 25 had inconclusive results and were submitted to PCR analysis, being negative for T. gallinae. Although no positive Passeriformes was found, the monitoring of the occurrence of this protozoan must continue, as it is known that it may easily cause a possible epidemic, leading to losses for the wild fauna that has endangered birds.

Reduced reflectance and altered color: The potential cost of external particulate matter accumulation on urban Rock Pigeon (Columba livia) feathers

Feather quality in birds is considered an honest signal of individual health as feather appearance and function depend on an individual’s ability to maintain them. In addition to flight and insulation, feathers are essential for social interactions and sexual selection in the form of visual signals. Airborne particulate matter (PM) can accumulate on feather surfaces and alter feather appearance. We quantified PM accumulation on Rock Pigeon (Columba livia) feathers and analyzed the spectral properties of extracted particulates. Feathers were sampled from two pigeon populations, one rural and one urban, in the Dallas-Fort Worth area, with 47 and 93% developed land cover, respectively, within 2 km of the populations. We determined accumulated PM gravimetrically after rinsing feathers and then measured the visible-near-infrared diffuse reflectance and color properties of extracted particulates. The rate of PM accumulation on rural birds was higher than on urban birds. However, feather particulates collected from urban pigeons had significantly lower total reflectance, reflectance in the visible portion of the spectrum, lightness, and hue angle compared to those of rural pigeons. The hue angle of rural feather particulates displayed a negative relationship with PM accumulation while total reflectance, reflectance in the visible range, and lightness of urban feather particulates were negatively related to PM accumulation. Our findings suggest that wild birds could incur an urban pollution penalty as PM accumulation has the potential to alter feather properties. Further research is needed to better understand the influence of external PM accumulation on the physiological and behavioral health of birds.