A genomic basis of vocal rhythm in birds.

Vocal rhythm plays a fundamental role in sexual selection and species recognition in birds, but little is known of its genetic basis due to the confounding effect of vocal learning in model systems. Uncovering its genetic basis could facilitate identifying genes potentially important in speciation. Here we investigate the genomic underpinnings of rhythm in vocal non-learning Pogoniulus tinkerbirds using 135 individual whole genomes distributed across a southern African hybrid zone. We find rhythm speed is associated with two genes that are also known to affect human speech, Neurexin-1 and Coenzyme Q8A. Models leveraging ancestry reveal these candidate loci also impact rhythmic stability, a trait linked with motor performance which is an indicator of quality. Character displacement in rhythmic stability suggests possible reinforcement against hybridization, supported by evidence of asymmetric assortative mating in the species producing faster, more stable rhythms. Because rhythm is omnipresent in animal communication, candidate genes identified here may shape vocal rhythm across birds and other vertebrates.

Evidence of West Nile virus seropositivity in wild birds on the island of Cyprus.

West Nile Virus (WNV)1 is an emerging pathogen in Cyprus, with the first human case of infection reported in 2016, and another documented in 2018. A cluster of cases in humans was then reported in 2019. However, little is known regarding which avian species might bring WNV to Cyprus. Here, we investigated seroprevalence of WNV antibodies in migratory and resident birds, captured across Cyprus to assess to what extent human populations might be exposed to WNV. We used Enzyme-Linked Immunosorbent Assay (ELISA)2 to test for the presence of WNV antibodies in 836 avian blood samples of 44 species captured between 2015 and 2020. A seropositivity rate of 1.3 % was found. The majority of seropositive wild birds belonged to the migratory species Sylvia atricapilla, a common and widespread migrant, implying a high risk of WNV being introduced throughout Cyprus.

CYP2J19 mediates carotenoid colour introgression across a natural avian hybrid zone.

It has long been of interest to identify the phenotypic traits that mediate reproductive isolation between related species, and more recently, the genes that underpin them. Much work has focused on identifying genes associated with animal colour, with the candidate gene CYP2J19 identified in laboratory studies as the ketolase converting yellow dietary carotenoids to red ketocarotenoids in birds with red pigments. However, evidence that CYP2J19 explains variation between red and yellow feather coloration in wild populations of birds is lacking. Hybrid zones provide the opportunity to identify genes associated with specific traits. Here we investigate genomic regions associated with colour in red-fronted and yellow-fronted tinkerbirds across a hybrid zone in southern Africa. We sampled 85 individuals, measuring spectral reflectance of forecrown feathers and scoring colours from photographs, while testing for carotenoid presence with Raman spectroscopy. We performed a genome-wide association study to identify associations with carotenoid-based coloration, using double-digest RAD sequencing aligned to a short-read whole genome of a Pogoniulus tinkerbird. Admixture mapping using 104,933 single nucleotide polymorphisms (SNPs) identified a region of chromosome 8 that includes CYP2J19 as the only locus with more than two SNPs significantly associated with both crown hue and crown score, while Raman spectra provided evidence of ketocarotenoids in red feathers. Asymmetric backcrossing in the hybrid zone suggests that yellow-fronted females mate more often with red-fronted males than vice versa. Female red-fronted tinkerbirds mating assortatively with red-crowned males is consistent with the hypothesis that converted carotenoids are an honest signal of quality.

Tape lures swell bycatch on a Mediterranean island harbouring illegal bird trapping.

Mediterranean islands provide shelter and sustenance for millions of migrating birds each year. Humans have historically exploited bird migration through hunting. In Cyprus, trapping birds during their migratory peak is considered a tradition, but has long been against the law. Illegal bird trapping is lucrative, however, with trappers using tape lures that broadcast birdsong to increase capture rates. It results in the slaughter of millions of birds each year. Yet, scientific studies quantifying capture rates of target and nontarget species using methods employed by trappers are lacking. Here, we show using playback experiments that tape lures lead to an order of magnitude greater capture rates of target species, but also significantly increase bycatch, which may include species of conservation concern. Conservation efforts focusing on minimizing illegal bird killing should also consider tape lures and their contribution to the overall impact of trapping on avian populations.

Spatial and temporal patterns in the diet of barn owl (Tyto alba) in Cyprus.

BACKGROUND: The barn owl, a nocturnal raptor with cosmopolitan distribution, shows a great adaptability to different environments. Regarding prey, the barn owl is a rather selective species, but if changes in the abundance of the selected prey occur, it becomes an opportunistic predator and easily incorporates other prey in its diet, using a wide range of prey species and foraging habitats. Small rodents are usually the prey mostly used. Compared to the populations of north and eastern Europe, barn owl populations in the Mediterranean area have been the least studied. In Cyprus, where barn owl is a common bird species, there are no studies on its diet and feeding ecology. This study was carried out to contribute to the spatial and temporal patterns barn owl diet in Cyprus also providing information on small mammals' presence and species composition on the island. METHODS: This study was based on 1407 regurgitated pellet analysis that were collected from 26 sites representing six major habitat types on central and southern Cyprus from summer 2013 to summer 2014. The diet of the barn owl was described in terms of seasonal average biomass and numerical percentages of each prey species and compared by Kruskal-Wallis test. Seasonal prey diversity and evenness indices were also calculated. Principal component analysis (PCA) was performed on the prey biomass proportion data assigned to six major habitat types with regard to elevation, vegetation and human uses. RESULTS: Low prey diversity was found comprised mainly of rodents (overall means 96.2 and 95.7% by number and biomass, respectively). Mice followed by rats were most important prey whereas insectivores, birds and insects were minor components of the owl's diet. Evenness and diversity values were relatively similar among seasons. PCA differentiated mainly between lowland areas where mice were more abundant prey and mountainous areas where rats dominated in the diet. Insectivores correlated with birds, prey types characterizing several lowland and highland habitats. CONCLUSIONS: The barn owl prey composition in Cyprus suggests an opportunistic foraging behavior, low prey species diversity with variations in the main rodent prey that could be explained by their distribution, seasonal activity and habitat preferences.