Young Birds Research Articles

Modulatory effects of inorganic mercury (Hg (II)) and lead (Pb (II)) on immune responses of Pekin ducklings (Anas platyrhynchos domesticus) upon a viral-like immune challenge

Trace metal contamination is ubiquitous around the world and may affect the health of wildlife. Divalent trace metals, including ions of mercury (Hg) and lead (Pb), have been shown to be immunotoxic to avian species. However, little is known about the immunomodulatory effects of trace metal exposure on viral infections, especially in young birds, who may be more sensitive. Therefore, the objective of the current study is to provide more insights in the causality between trace metal exposure and the effects of exposure on the immune responses in young waterfowls. Pekin duckling was used as an animal model to investigate the effects of inorganic divalent Hg (II) and Pb (II) on avian immune responses upon a viral-like challenge with double-stranded RNA. Our results indicate that Hg (II) altered the immune gene expression 24 h post-challenge, as reflected by induction of pro-inflammatory genes IL-8, iNOS, TLR3 and TLR7, and a significant decrease of microRNA-155. Ducklings exposed to Pb (II) showed lower levels of natural antibodies, reduced white blood cell counts and lower heterophil proportions 24 h post-challenge. Although inorganic divalent Hg (II) and Pb (II) showed specific differential effects on the immune response of Pekin ducklings, the overall adverse immunomodulatory outcomes in both cases point to inflammation, impaired B-cell function, and weaker immunocompetence.

Noisy nests: Early-life noise exposure impacts songbird fitness.

Recent findings indicate that noise pollution - presented in the absence of other variables - has both immediate-term impacts on young birds' developmental rates and physiology as well as long-term effects on adult telomere length and reproductive success. This work highlights yet another set of negative impacts caused by anthropogenic noise, and suggests that the dramatic fitness consequences observed likely have implications for the evolution of learning and behavior in animals living in noisy environments.

Manipulating a host-native microbial strain compensates for low microbial diversity by increasing weight gain in a wild bird population

Empirical studies from laboratory systems and humans show that the gut microbiota is linked to host health. Similar evidence for effects on traits linked to fitness in nature is rare, not least because experimentally manipulating the gut microbiota is challenging. We isolated, characterized, and cultured a bacterial strain, Lactobacillus kimchicus APC4233, directly from a wild bird (the great tit Parus major) and provided it as a self-administered dietary supplement. We assessed the impact of the treatment on the host microbiota community, on weight, and tested whether the treatment affected a previous result linking microbiota alpha diversity to weight in nestlings. The treatment dramatically increased L. kimchicus abundance in the gut microbiota and increased alpha diversity. This effect was strongest in the youngest birds, validating earlier findings pointing to a brief developmental window when the gut microbiota are most sensitive. In time-lagged models, nestling weight was higher in the treatment birds suggesting L. kimchicus may have probiotic potential. There was also a positive time-lagged relationship between diversity and weight in control birds but not in the treatment birds, suggesting L. kimchicus helped birds compensate for low alpha diversity. We discuss why ecological context is likely key when predicting impacts of the microbiome. The manipulation of the gut microbiota with a host native strain in this wild population provides direct evidence for the role of the microbiota in the ecology and evolution of natural populations.

Broiler chicken vocalization analysis during a medium-scale heat stress experiment

The poultry industry in Flanders, Belgium, is characterized by highly efficient production mechanisms. To improve awareness for animal health and welfare, the use of neural network-based broiler vocalization detectors has been recently proposed in scientific literature. However, these tools have not yet been tested when used continuously in large-scale deployments. This paper describes the deployment of the broiler vocalization detector to analyze the sonic environment during four experimental rounds, each containing 560 broilers, in a medium scale housing at ILVO, Belgium. Half the broilers were subjected to periods of heat stress (ambient temperature increased to 32°C for 6h/day for 10 days during the last weeks of their lives) and the effect on the diurnal broiler vocalization pattern and occurrence of warbles, pleasure notes, short beeps and distress calls is discussed. While these four different types of vocalizations are common vocalizations in young birds, new types of vocalizations are emerging at an older age. A clustering has been performed to further analyze these new types of vocalizations occurring.

Blue Light-Induced Accelerated Formation of Melanolipofuscin-Like Organelles in Japanese Quail RPE Cells: An Electron Microscopic Study.

The retinal pigment epithelium (RPE) is a monolayer of epithelial cells essential for photoreceptor function and viability. Quail Coturnix japonica is a convenient experimental animal model for the study of age and pathological retina processes to an accelerated time regime. The three main types of pigment granules present in the RPE are melanin-containing melanosomes, lipofuscin-containing lipofuscin granules, and mixed melanolipofuscin granules containing both melanin and lipofuscin. The purpose of this work was to study the process of melanolipofuscinogenesis during aging and under light exposure. We examined melanolipofuscin granules in "macular" areas, the area of the retina containing oxycarotenoids, as a function of the macula in humans, of the quail retina by transmission electron microscopy in young, middle-aged, and old birds, and in middle-aged birds irradiated with blue LED light (450 nm, 4 J/cm2). It has been shown that during photo-oxidative stress caused by the action of blue light on the quail eye, active fusion of melanosomes and lipofuscin granules occurs with formation of various types, including giant, mixed melanolipofuscin-like granules. Increased accumulation of melanolipofuscin-like granules was also observed in non-irradiated old birds. It is assumed that the decrease in the number of melanosomes in the RPE during aging and photo-oxidative stress is associated with their fusion with lipofuscin granules and subsequent degradation of melanin by reactive oxygen species formed in melanolipofuscin-like granules. The disappearance of melanin deprives the RPE cells of light-filtering and antioxidant protection, and significantly increases the risk of their oxidative stress.

BREEDING ASPECTS OF GUBERNETES YETAPA (AVES, TYRANNIDAE) IN RIO GRANDE DO SUL STATE, BRAZIL

The Streamer-tailed Tyrant (Gubernetes yetapa) is an exclusively neotropical bird, associated with wetlands and widely distributed in Brazil. This study aimed to fill gaps in knowledge about this species, especially regarding its reproductive biology. We monitor a population of G. yetapa with the aim of describing its reproductive behavior, nest characteristics, and territory use in a wetland in the state of Rio Grande do Sul. Our findings revealed that this wetland serves as an important breeding site, where the total home range of the species was 28.2 ha, significantly reduced to 3.37 ha during the breeding season. The nest described here contained three eggs, two of which hatched successfully. After leaving the nest, the young birds foraged independently before joining mixed flocks with other species of birds. This study sheds light on the breeding ecology of the species and highlights the importance of wetlands for its conservation.

Social and auditory experience shapes forebrain responsiveness in zebra finches before the sensitive period of vocal learning.

Early-life experiences with signals used in communication are instrumental in shaping an animal's social interactions. In songbirds, which use vocalizations for guiding social interactions and mate choice, recent studies show that sensory effects on development occur earlier than previously expected, even in embryos and nestlings. Here, we explore the neural dynamics underlying experience-dependent song categorization in young birds prior to the traditionally studied sensitive period of vocal learning that begins around 3 weeks post-hatch. We raised zebra finches either with their biological parents, cross-fostered by Bengalese finches beginning at embryonic day 9, or by only the non-singing mother from 2 days post-hatch. Then, 1-5 days after fledging, we conducted behavioral experiments and extracellular recordings in the auditory forebrain to test responses to zebra finch and Bengalese finch songs. Auditory forebrain neurons in cross-fostered and isolate birds showed increases in firing rate and decreases in responsiveness and selectivity. In cross-fostered birds, decreases in responsiveness and selectivity relative to white noise were specific to conspecific song stimuli, which paralleled behavioral attentiveness to conspecific songs in those same birds. This study shows that auditory and social experience can already impact song 'type' processing in the brains of nestlings, and that brain changes at this age can portend the effects of natal experience in adults.

Research Note: Dynamics of black grouse (Tetrao tetrix) infestation with various Eimeria species

The black grouse (Tetrao tetrix) is an endangered species facing challenges in breeding and reintroduction programs, including parasitic infestations. This study aimed to assess natural infestations by various Eimeria species and infestation dynamics in female, male, and young black grouse kept in a stationary aviary. Faecal samples were collected from adult grouses between April and the time of chicks' hatching and rearing (September). Faecal samples from young birds were collected from the hatching for a period of 1 year. The prevalence of Eimeria spp. was determined by a qualitative method (Fulleborn's flotation) and a quantitative method (McMaster's method with Raynaud's modification). The following Eimeria species were identified: E. lyruri, E. nadsoni and E. nonbrumpti. The average percentages of Eimeria spp. in the cock were 80.52%, 9.27%, and 10.21%, respectively; in the hen, they were 86.19%, 9.28%, and 4.53%, respectively; in the young black grouses they were 84.60%, 9.34% and 6.06%, respectively. The highest E. lyruri infestation was observed in the cock in June (144227 OPG) and July (129365 OPG). In the hen, the infestation intensity increased in May (304302 OPG) and then decreased in June (39583 OPG). Furthermore, an additional increase was observed in July (216533 OPG). Two increases in infestation intensity were also observed in young birds, with peaks in January (91387 OPG) and July (126178 OPG). A positive strong correlation was identified between Eimeria spp. in the cock and the young birds. A statistically significant positive correlation was identified in the hen between E. lyruri and E. nadsoni. No correlation was demonstrated between the infestation intensity and the age of the birds or season of the year in all the grouses under study. Despite some attempts, a comprehensive approach to the issue of coccidiosis in the black grouse as a disease that may affect the success of reintroduction has yet to be established. It seems crucial to monitor the level of Eimeria spp. invasion, and the proposed faecal sampling scheme is an important tool for achieving this goal.

Molecular phylogenetic analysis and seasonal dynamics of Eimeria species infecting broilers of Kashmir, India.

Globally, the poultry industry is seriously threatened by coccidiosis caused by various species of Eimeria. This protozoan parasite inhabits the epithelial lining of the gastrointestinal tract of poultry globally and can cause serious clinical disease. The present study was carried out on poultry farms located in various regions of Kashmir, India, to investigate the prevalence and phylogenetic relationships of Eimeria species affecting broiler chickens. Over a period of one year, fecal samples were collected from 60 poultry farms in Kashmir and morphological and molecular techniques were employed for Eimeria species identification. Results revealed a high prevalence of coccidiosis, with 58.3% (35/60) of farms positive for Eimeria. The most prevalent species were E. tenella (31/35, 88.6%) followed by E. acervulina (25/35, 71.4%), E. maxima (19/35, 54.3%), E. mitis (18/35, 51.4%), and E. necatrix (9/35, 25.7%). Seasonal variation in prevalence was also observed, with the highest rates in autumn (86.7%) and summer (66.7%). Additionally, younger birds (3-4weeks) exhibited higher infection rates (85.7%) compared to older birds (57.9%) (5-6weeks). Mixed infection was found in 94.2% (33/35) of positive farms. Phylogenetic analysis using ITS1 sequences confirmed species clustering and revealed evolutionary relationships among Eimeria species. E. tenella and E. necatrix formed a distinct clade, while E. acervulina formed another. The study underscores the importance of molecular techniques in accurate species identification and provides valuable insights into the epidemiology of coccidiosis in poultry in Kashmir. Effective control strategies, including vaccination and improved management practices, are necessary to mitigate the economic losses associated with this widespread poultry disease.

Breeding success of eurasian cranes (<i>grus grus</i>, gruiformes, aves) in the conditions of a changing environment: the impact of climatic and hydrometeorological trends

Theoretical predictions usually assume that changes in conditions caused by climate warming would render negative effects on the population dynamics of many bird species, but evidence is only rarely presented. Changes in phenology, nesting timing, and the physical condition of breeders have been published for a wide range of species in most regions of the Northern Hemisphere; however, data are still insufficient for a better understanding of the consequences for changes in productivity, reproductive success and offspring recruitment. Long-term monitoring (1994–2023) the numbers and age structure of premigratory gatherings of Eurasian cranes in the northern Moscow Region, Central Russia, reveals that, despite the climate warming in the region, the proportion of offspring has not changed over the 30-year long period of observation. The number of young birds is positively related to the temperature of the breeding season; in warmer years, the productivity of Eurasian cranes was higher. In seasons with high precipitation rates, the proportion of chicks was decreased. The reproduction efficiency of cranes on Central Russia is controlled by two parameters: the amount of precipitation and the average temperature during the breeding season.More chicks rise in years with a combination of higher temperatures and low precipitation amounts. Increased precipitations and decreased temperatures lead to reduced proportions of chicks in the premigratory gatherings. The most unfavorable situation for common cranes was low temperatures combined with high precipitations, the proportion of chicks being the minimum in such years.

Assessing preferences for adult versus juvenile features in young animals: Newly hatched chicks spontaneously approach red and large stimuli.

Young precocial birds benefit from staying close to both their mother and their siblings, while prioritising adults, which provide better care. Which features of the stimuli are used by young birds to prioritise approach and eventually attachment to adults over siblings is unknown. We started to address this question in newly hatched domestic chicks (Gallus gallus), focusing on their spontaneous preferences for visual features that systematically vary between adult and juvenile chickens, and that had previously been identified as attractive: size (larger in adults than in juveniles) and colour (darker and redder in adults than in juveniles). Overall, chicks at their first visual experience, that had never seen a conspecific beforehand, were most attracted to the red and large stimuli (two adult features) and spent more time in close proximity with red stimuli than with yellow stimuli. When tested with red large versus small objects (Exp. 1), chicks preferred the large shape. When tested with yellow large and small objects (Exp. 2), chicks did not show a preference. Chicks had a stronger preference for large red stimuli (vs. small yellow objects) than for small red stimuli (vs. a large yellow object) (Exp. 3). These results suggest that the combination of size and colour form the predisposition that helps chicks to spontaneously discriminate between adult and juvenile features from the first stages of life, in the absence of previous experience, exhibiting a preference to approach stimuli with features associated with the presence of adult conspecifics.

A comparative assessment of age-related nicotinamide adenine dinucleotide phosphate-diaphorase positivity in the spinal cord and medulla oblongata of pigeons, rats, and mice.

Nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase (N-d) positive neurons have been extensively studied across various animals, and N-d neurodegenerative neurites have been detected in some aged animal models. However, detailed knowledge on N-d positivity and aging-related alterations in the spinal cord and medulla oblongata of pigeons is limited. In this study, we investigated N-d positivity and age-related changes in the pigeon's spinal cord and medulla oblongata and compared them to those in rats and mice. Pigeons, had more N-d neurons in the dorsal horn, around the central canal, and in the column of Terni in the thoracic and lumbar segments, with scattered neurons found in the ventral horn of the spinal segments. N-d neurons were also present in the white matter of the spinal cord. Morphometric analysis revealed that the size of N-d soma in the lumbosacral, cervical, and thoracic regions was substantially altered in aged pigeons compared to young birds. Furthermore, the lumbar to sacral segments underwent significant morphological alterations. The main findings of this study were the presence of age-related N-d positive bodies (ANB) in aged pigeons, predominantly in the external cuneate nucleus (CuE) and occasionally in the gracilis and CuEs. ANBs were also identified in the gracile nuclei and spinal cord in the aged rats and mice, whereas in aged rats, ANBs were detected in the CuE spinal nucleus. Immunohistochemistry showed that the age-related alterations occurred in the cell types and neuropeptides in old animals. The results suggest weak inflammatory response and neuronal dysfunction in the spinal cord in aged pigeons. Our results suggested that the ANB could be a potential aging marker for the central nervous system.

Multidrug Resistant Pseudomonas aeruginosa Isolated from Chicken: A Public Health Concern

Infection of Pseudomonas aeruginosa has been responsible for economic losses in younger birds. This research was designed to report and document multidrug resistant P. aeruginosa recovered from chicken during infection. Sixty-seven freshly dead chicken were used in this research, the trachea, the liver, and the heart were targeted for P. aeruginosa isolation. The isolates were identified based on the cultural, morphological, and biochemical characteristics. Antimicrobial test was carried out on the pure isolates using the disc diffusion method. A total of 23 isolates of P. aeruginosa were recovered; 19 isolates were recovered from the trachea, 3 from the liver and 1 from the heart. All the isolates were showing green pigment on nutrient agar, they were all Gram-negative rods, motile, catalase and citrate positive. The result of the antibiotic susceptibility showed that ampicillin was most resisted with a resistance of 95.7% (22) while gentamicin was least resisted with 39.1% (9), and 69.5% (16) of the isolates were showing resistance to more than three antibiotics. The most encountered resistant pattern was AMP, TLY with 87%. The result from this study revealed that multidrug resistant P. aeruginosa in poultry may be emerging and serving as a reservoir for resistant P. aeruginosa gene.

Are Current Protection Methods Ensuring the Safe Emancipation of Young Black Storks? Telemetry Study of Space Use by Black Storks (Ciconia nigra) in the Early Post-Breeding Period.

The black stork is a protected species in Poland, and its numbers have declined significantly in recent years. The protection of nesting sites during the period of growth and independence of young birds is crucial for the population. In 2022-2023, 34 young storks were equipped with GPS-GSM backpack loggers. On average, birds had left the nest by the 87th day of life. In the period between the first flight attempt and the final abandonment of the nest, the birds spent 82% of their time in a zone up to 200 m from the nest. During the period of independence, resting areas played an important spatial role, 75% of which were located within 500 m of the nest. As the young birds grew older, their area of activity gradually increased. Differences in nesting phenology were observed depending on the geographical location of the nest. A shorter migration route from the wintering grounds allowed for earlier breeding. As a result, the young birds begin to fledge earlier. The data collected confirm the validity of designating protective zones with 500 m radii around nests and the need to maintain them from the beginning of the breeding season in March until the end of August.

Färgvariation hos vattenpiplärka Anthus spinoletta i vinterdräkt

This study of colour variation on Water Pipit Anthus spinoletta in winter plumage, is based on photos of 93 individuals from southern Sweden. Using moulting criteria, the birds were aged from the photographs, and the presence or absence of five specific plumage characteristics were recorded. Twelve individuals in this study confirm the hypothesis that adult Water Pipits show a distinct combination of plumage traits during winter. However, the presence of these plumage traits varied in younger birds in their first winter plumage. Among the 81 individuals classified as first winter plumage, 23 (28%) displayed all “adult characteristics”, 32 (40%) one to four of the characteristics, while 26 (32%) lacked all “adult characteristics”. The latter group thus lacked a gray nape/crown, whitish supercilium, and lighter brown colouration of the mantle/scapulars. Ever since the first Swedish records in the mid-1990s, there have been ongoing discussions regarding species-specific characters in Water Pipits. The present quantification of colour variation in different age groups complements previous criteria for a reliable species identification of Water Pipits in winter plumage.

Habitat use of Amazonian birds varies by age and foraging guild along a disturbance gradient.

Patterns of habitat use directly influence a species' fitness, yet for many species an individual's age can influence patterns of habitat use. However, in tropical rainforests, which host the greatest terrestrial species diversity, little is known about how age classes of different species use different adjacent habitats of varying quality. We use long-term mist net data from the Amazon rainforest to assess patterns of habitat use among adult, adolescent (teenage) and young understory birds in forest fragments, primary and secondary forest at the Biological Dynamics of Forest Fragments Project in Brazil. Insectivore adults were most common in primary forest, adolescents were equally likely in primary and secondary forest, and all ages were the least common in forest fragments. In contrast to insectivores, frugivores and omnivores showed no differences among all three habitat types. Our results illustrate potential ideal despotic distributions among breeding populations of some guilds of understory birds where adult insectivores may competitively exclude adolescent individuals from primary forest. Secondary forest recovery appears to hold promise as a breeding habitat for frugivore and omnivore species but only as a pre-breeding habitat for insectivores, but as the forest ages, the demographic structure of bird populations should match that of primary forest.

Utilizing 3-dimensional models to assess keel bone damage in laying hens throughout the lay cycle

The global egg industry is rapidly transitioning to cage-free egg production from conventional cages. Hens housed in cage-free systems have an increased prevalence of keel damage that could lead to reduced egg production and compromised well-being. The objective of this study was to determine the effects of dietary supplementation of n-3 fatty acids and vitamin D3 on keel damage in hens housed in multi-tier aviary systems (AV). Brown hens were placed in 4 AV system rooms after rearing at 17 wk of age (woa) with each room containing 576 birds. At 12 woa, rooms were randomly assigned to a dietary treatment of flaxseed oil, fish oil, vitamin D3, or control. Focal birds (36 per treatment) were longitudinally examined for keel damage using quantitative computed tomography (QCT) at nine timepoints from 16 to 52 woa. Three-dimensional digital twins of the keels were created from the QCT scans and visually assessed for damage. An overall keel severity score was recorded as well as the location, direction, and severity of each deviation or fracture. Severity was ranked on a 0 to 5 scale with 0 being no damage and 5 being severe. Damage scores were analyzed utilizing odds ratios with main effects of age and treatment. At 16 woa, 80% of hens had overall keel scores of 0 and 20% had scores of 1. At 52 woa, all hens had damage, with 31% having a score of 1, 61% scored 2 to 3, and 8% scored 4 to 5. Most fractures were not observed until peak lay. Dietary treatments did not affect likelihood of fracture incidences, but younger birds had lower odds of incurring keel fractures than older birds (P < 0.0001). The initial incidences of keel deviations occurred earlier than fractures, with most birds obtaining a keel deviation by 28 woa. Keel damage was not able to be prevented, but the age at which keel fractures and deviations initiate appear to be different, with deviations occurring during growth and fractures during lay.

Avian Polyomavirus Among Psittacine Birds in Iran: Molecular Detection Rate and Associated Risk Factors.

Avian polyomavirus (APV) infection causes various health problems in psittacine species, including death. The present study was conducted to investigate the prevalence of APV among psittacine birds in Iran. We also aimed to evaluate the impact of age, sex, species, season, and origin of the birds on the prevalence of APV. This study investigated the presence of APV among 1050 individual birds from 7 psittacine species over a 1-year period in Iran, namely, green-cheeked parakeets (Pyrrhura molinae), rosy-faced lovebirds (Agapornis roseicollis), monk parakeets (Myiopsitta monachus), sun conures (Aratinga solstitialis), Senegal parrots (Poicephalus senegalus), cockatiels (Nymphicus hollandicus), and grey parrots (Psittacus erithacus). The overall prevalence of APV in all studied species was 25% (263/1050, 95% confidence interval [CI]: 22.5-27.8). Results of the study showed that age and the season of the year were 2 important determinant factors in the prevalence of APV in psittacine birds. Young psittacine birds <6 months old were 2.94 (95% CI: 1.19-7.27) times more likely to be infected with APV than birds >1 year old, and there was a significant interaction between season and species in the multivariate analysis. In the winter season, rosy-faced lovebirds and green-cheeked parakeets were 15.6 (95% CI: 4.20-57.95) and 4.76 (95% CI: 1.4-16.21) times more likely to be infected with APV than in other seasons, respectively. This is the first report on the detection rate of APV in psittacine birds in Iran.

Mortality rates in the national bird ringing programme of Denmark and the Faroe Islands

ABSTRACT Capsule Mortality varies across capture methods but remains overall low. Aims To investigate mortality associated with ringing operations in Denmark and the Faroe Islands, including the effects of species and capture methods. Methods We analyzed data for mortality rates of birds arising from ringing operations in Denmark and the Faroe Islands over a 20-year period. The data included a variety of capture methods and altogether the reports involve 1.8 million individuals. Results The overall mortality rate during ringing operations was 0.16%. The dominant form of capture, mist-netting, had a mortality rate of 0.21%, comparable to similar published studies. Capture methods with higher mortality rates were generally used in research aimed at informing management decisions. Predation was directly responsible for most deaths, with the Eurasian Sparrowhawk Accipiter nisus being the most common predator of birds captured in nets. Migrating passerines occurring in large numbers at bird observatories contributed most to the mortality rates in Denmark, with young birds on their first autumn migration being especially prevalent. Conclusions Overall, our study confirms that bird ringing remains an acceptable method of data collection and highlights the variation in mortality among species and methods. The results should be used to inform working practices to minimize any associated mortality, as far as possible.

Avian Polyomavirus Among Psittacine Birds in Iran: Molecular Detection Rate and Associated Risk Factors.

Avian polyomavirus (APV) infection causes various health problems in psittacine species, including death. The present study was conducted to investigate the prevalence of APV among psittacine birds in Iran. We also aimed to evaluate the impact of age, sex, species, season, and origin of the birds on the prevalence of APV. This study investigated the presence of APV among 1050 individual birds from 7 psittacine species over a 1-year period in Iran, namely, green-cheeked parakeets (Pyrrhura molinae), rosy-faced lovebirds (Agapornis roseicollis), monk parakeets (Myiopsitta monachus), sun conures (Aratinga solstitialis), Senegal parrots (Poicephalus senegalus), cockatiels (Nymphicus hollandicus), and grey parrots (Psittacus erithacus). The overall prevalence of APV in all studied species was 25% (263/1050, 95% confidence interval [CI]: 22.5-27.8). Results of the study showed that age and the season of the year were 2 important determinant factors in the prevalence of APV in psittacine birds. Young psittacine birds <6 months old were 2.94 (95% CI: 1.19-7.27) times more likely to be infected with APV than birds >1 year old, and there was a significant interaction between season and species in the multivariate analysis. In the winter season, rosy-faced lovebirds and green-cheeked parakeets were 15.6 (95% CI: 4.20-57.95) and 4.76 (95% CI: 1.4-16.21) times more likely to be infected with APV than in other seasons, respectively. This is the first report on the detection rate of APV in psittacine birds in Iran.