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The microbiota's alteration is an adaptive mechanism observed in wild animals facing high selection pressure, especially in captive environments. The objective of this study is to compare and predict the potential impact of habitat on the fecal bacterial community of Saltator similis, a songbird species that is a victim of illegal trafficking, living in two distinct habitats: wild and captivity. Nine wild and nine captive S. similis were sampled, and total bacterial DNA was obtained from the feces. Each DNA sample was employed to the amplification of the V4 region of the 16S rDNA following high-throughput sequencing. The most predominant phyla in all songbirds, irrespective of habitat, were Firmicutes, Bacteroidota, Proteobacteria, and Actinobacteriota. Interestingly, a microbiota profile (phylogenetic and abundance relationship) related to habitat was identified. The genera "Candidatus Arthromitus", Acinetobacter, Kocuria, and Paracoccus were exclusively identified in animals living in captivity, which can be a potential biomarker associated with birds in captive environments. This study presents the first description of the fecal bacterial community composition of S. similis living two different lifestyles. Finally, our results suggest that the lifestyle of S. similis birds significantly impacts the composition of the fecal microbiota. The animals living in captivity showed dysbiosis in the microbiota, with some bacteria genera being indicated as biological markers of environmental behavior. Thus, the present research provides a new concept of life quality measure for songbirds.

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Poxviruses (family: Poxviridae) infect many avian species, causing several disease outcomes, the most common of which are proliferative lesions on the legs, feet, and/or head. Few avian studies of poxvirus to date have combined molecular and ecological analyses to obtain a more comprehensive understanding of the identity and distribution of the disease in a population. Here, we describe patterns of poxvirus infection in an urban population of house finches (Haemorhous mexicanus) in Arizona (USA) and use high-throughput sequencing to determine the genome sequence of the virus. We found that poxvirus prevalence, based on visual identification of pox lesions, was 7.2% (17 infected birds out of a total of 235 sampled) in our population during summer 2021. Disease severity was low; 14 of the 17 infected birds had a single small lesion on the skin overlaying the eye, leg, and ear canal. All but two lesions were found on the feet; one bird had a lesion on the eye and the other in the ear opening. We also investigated possible temporal (i.e., date of capture) and biological correlates (e.g., age, sex, body condition, degree of infection with coccidian endoparasites) of poxvirus infection in urban-caught house finches during this time but found that none of these significantly correlated with poxvirus presence/absence. Two complete poxvirus genomes were determined from two infected birds. These genomes are ∼354,000 bp and share 99.7% similarity with each other, and 82% with a canarypox virus genome, the most closely related avipoxvirus. This novel finchpox virus is the first to be reported in house finches and has a similar genome organization to other avipoxviruses.

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How vocal communication signals are represented in the cortex is a major challenge for behavioural neuroscience. Beyond a descriptive code, it is relevant to unveil the dynamical mechanism responsible for the neural representation of auditory stimuli. In this work, we report evidence of synchronous neural activity in nucleus HVC, a telencephalic area of canaries (Serinus canaria), in response to auditory playback of the bird's own song. The rhythmic features of canary song allowed us to show that this large-scale synchronization was locked to defined features of the behaviour. We recorded neural activity in a brain region where sensorimotor integration occurs, showing the presence of well-defined oscillations in the local field potentials, which are locked to song rhythm. We also show a correspondence between local field potentials, multiunit activity and single unit activity within the same brain region. Overall, our results show that the rhythmic features of the vocal behaviour are represented in a telencephalic region of canaries.

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The illegal capture and trade of wild birds have long been threats to biodiversity. The rehabilitation and release of confiscated animals may be a useful conservation tool in species management. However, differences between populations regarding health (e.g., different pathogens) and adaptation (e.g., local adaptation) must be taken into account, since both can negatively impact the recipient population. In this pilot study, we used two of the most illegally trafficked Brazilian wild passerine species, namely the red-crested cardinal (Paroaria coronata) and green-winged saltator (Saltator similis) as case studies and assessed some of the health threats that the release of confiscated passerines may pose to free-living birds. We also investigated the level of difference in mitochondrial genetic structure among populations living in different ecoregions. Blood, feces, and oropharyngeal swabs from confiscated (n = 115) and free-living (n = 120) passerines from the release sites were tested for the Newcastle disease virus, Salmonella spp., and Mycoplasma gallisepticum. These are considered major avian diseases by the Brazilian National Avian Health Program. We analyzed mtDNA to study the difference in genetic structure between populations using samples from 127 free-living passerines. We found no evidence of the Newcastle disease virus or Salmonella spp. in confiscated or free-living passerines from either species. However, the levels of infection with M. galissepticum detected in our study for red-crested cardinals and green-winged saltators calls for a high degree of caution in captive release programs. The difference in genetic structure between populations occurring in different regions was low, and was not significant between those from the Pampa/Subtropical Grasslands region. These results suggest that it may be possible to establish a cost-effective and sensitive protocol for releasing confiscated songbirds, provided that further genome-wide studies indicate that the functional genetic diversity among (at least some of the) populations is also low.

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Plasma cholinesterase activity is a biomarker sensitive to the effect of organophosphate and carbamate pesticides, and its enzymatic levels have been previously unknown for most of the wild birds analyzed in the present study. Our objectives were to establish plasma acetylcholinesterase levels in songbirds of 2 undisturbed sites in the central Monte Desert (Argentina). We also examined the influence on cholinesterase activity of age, sex, body condition, feeding and migratory habits, and species. One hundred and sixty-five wild birds belonging to 26 species were studied. The values obtained for acetylcholinesterase activity provide a good estimate of the normal values in free-living individuals of the species Zonotrichia capensis, Molothrus bonariensis, Passer domesticus, Diuca diuca, Poospiza ornata, Saltator aurantiirostris, Gryseotyrannus aurantioatrocristatus, and Columbina picui, with interspecies differences. The median enzymatic levels ± standard error of the mean ranged from 546.31 ± 17.97 µmol min-1 L-1 in P. domesticus to 3439.90 ± 173.92 µmol min-1 L-1 in Tyrannus melancholicus. No significant differences were detected between different sexes or ages. Birds that migrate (which are also insectivores) showed higher levels of cholinesterase than residents (mainly granivores). It is recommended that in cases of bird poisoning, plasma cholinesterase activity can be used as a diagnostic tool only if pre-exposure levels obtained in the same species are available, and ideally evaluated in individuals from the same biogeographical region. Environ Toxicol Chem 2019;38:1692-1700. © 2019 SETAC.

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There is growing interest in latitudinal effects on animal behaviour and life history. One recent focus is on birdsong, which is hypothesized to be more elaborated or complex in the north temperate zone compared with the tropics. Current evidence is mixed and based on cross-species comparisons, or single species with restricted distributions. We circumvent these limitations using a transcontinental sample of 358 songs from house wrens (Troglodytes aedon) at 281 locations spanning more than 100° of latitude (52° N-55° S) across the Americas. We found a significant latitudinal gradient in several basic elements of song performance and complexity between north temperate and tropical populations. Furthermore, we document convergence in song patterns between populations at higher latitudes in the Northern and Southern Hemispheres. Effects were strongest for the number of elements in a song, and the rate of element production, both increasing towards the poles, with similar but weaker effects for other song dimensions (e.g. number of unique elements, trills and trill rate). We consider possible causes related to variable habitats and morphology, concluding that the shorter breeding seasons at higher latitudes in both hemispheres may favour greater song elaboration to mediate territory competition and mate choice.

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Recent modeling analysis suggests that numerous birds may be at risk of acute poisoning in insecticide-treated fields. Although the majority of avian field studies on pesticides have focused on treated seed, granule, insect or vegetation (oral exposure) ingestion, dermal exposure is an important exposure route when birds come into contact with deposited pesticides on foliage and other surfaces. Some nearctic-neotropical migratory songbirds are likely exposed to pesticides on their non-breeding habitats and include treated crops, plantations or farmlands. In the present study, we developed a method for four environmentally-relevant organophosphate (OP) pesticides (fenthion, fenamiphos, chlorpyrifos and diazinon) in the feet of migratory songbirds (i.e. Common yellowthroat, Gray catbird, Indigo bunting, America redstart, Northern waterthrush, Northern parula, and an additional 12 species of warblers). A total of 190 specimens of the 18 species of songbirds were sampled from available window-killed birds (spring of 2007 and 2011) in downtown Toronto, Canada. The species that were available most likely over-wintered in Mexican/Central American crops such as citrus, coffee and cacao. The feet of the dead birds were sampled and where OP foot exposure likely occurred during over-wintering foraging on pesticide-treated crops. Chlorpyrifos was the only measurable OP (pg mg feet weight(-1)) and in the 2011-collected feet of Black throated blue warbler (0.5), Tennessee warbler (1.0), Northern parula (1.2), Northern waterthrush (0.6), Common yellowthroat (1.0) and the Blue winged warbler (0.9). Dermal contact with OP pesticides during over-wintering in agricultural areas resulted in low levels of chlorpyrifos and long time retention on the feet of a subset of songbirds.

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Approximately two thirds of migratory songbirds in eastern North America negotiate the Gulf of Mexico (GOM), where inclement weather coupled with no refueling or resting opportunities can be lethal. However, decisions made when navigating such features and their consequences remain largely unknown due to technological limitations of tracking small animals over large areas. We used automated radio telemetry to track three songbird species (Red-eyed Vireo, Swainson's Thrush, Wood Thrush) from coastal Alabama to the northern Yucatan Peninsula (YP) during fall migration. Detecting songbirds after crossing ∼1,000 km of open water allowed us to examine intrinsic (age, wing length, fat) and extrinsic (weather, date) variables shaping departure decisions, arrival at the YP, and crossing times. Large fat reserves and low humidity, indicative of beneficial synoptic weather patterns, favored southward departure across the Gulf. Individuals detected in the YP departed with large fat reserves and later in the fall with profitable winds, and flight durations (mean = 22.4 h) were positively related to wind profit. Age was not related to departure behavior, arrival, or travel time. However, vireos negotiated the GOM differently than thrushes, including different departure decisions, lower probability of detection in the YP, and longer crossing times. Defense of winter territories by thrushes but not vireos and species-specific foraging habits may explain the divergent migratory behaviors. Fat reserves appear extremely important to departure decisions and arrival in the YP. As habitat along the GOM is degraded, birds may be limited in their ability to acquire fat to cross the Gulf.

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1. Food availability has been considered one of the most important factors limiting bird populations, yet the effects of food abundance on non-breeding insectivores has rarely been investigated. We studied the effects of food abundance on the body condition of ovenbirds (Seiurus aurocapillus L.), a sexually monomorphic, ground-foraging, Neotropical-Nearctic migrant warbler during two winters in three habitats on their wintering grounds in Jamaica. 2. Prey biomass decreased from early to late winter in all habitats. Concurrently, ovenbird body mass, corrected for differences in structural size, decreased significantly in five of six habitat-year combinations. Only in second growth scrub habitat in the 1995-96 winter did ovenbirds show no decrease in corrected body mass, and during this period there was no significant decrease in ant biomass, the dominant prey item of ovenbirds in all habitats. 3. Significant positive correlations were found between ovenbirds' rate of feather regrowth and the biomass of ants on their home ranges in early winter, and between overwinter change in ovenbird body mass and the biomass of ants on their home ranges in late winter. 4. The results of both the habitat- and home-range-based analyses suggest a similar threshold of ant biomass (2·5-3·0 mg m-2 ), below which ovenbirds did not maintain their body mass. 5. The results suggest that late winter rainfall mediates the biomass of prey abundance, which in turn affects the ovenbirds' overwinter body condition.