Does Avian Coronavirus Co-Circulate with Avian Paramyxovirus and Avian Influenza Virus in Wild Ducks in Siberia?

Avian coronaviruses (ACoV) have been shown to be highly prevalent in wild bird populations. More work on avian coronavirus detection and diversity estimation is needed for the breeding territories of migrating birds, where the high diversity and high prevalence of Orthomyxoviridae and Paramyxoviridae have already been shown in wild birds. In order to detect ACoV RNA, we conducted PCR diagnostics of cloacal swab samples from birds, which we monitored during avian influenza A virus surveillance activities. Samples from two distant Asian regions of Russia (Sakhalin region and Novosibirsk region) were tested. Amplified fragments of the RNA-dependent RNA-polymerase (RdRp) of positive samples were partially sequenced to determine the species of Coronaviridae represented. The study revealed a high presence of ACoV among wild birds in Russia. Moreover, there was a high presence of birds co-infected with avian coronavirus, avian influenza virus, and avian paramyxovirus. We found one case of triple co-infection in a Northern Pintail (Anas acuta). Phylogenetic analysis revealed the circulation of a Gammacoronavirus species. A Deltacoronavirus species was not detected, which supports the data regarding the low prevalence of deltacoronaviruses among surveyed bird species.

Autumn migration tracks of Helopsaltes grasshopper-warblers from Northeast Asia support recent taxonomic assignments.

Migration strategies are genetically inherited in most songbirds, and closely related species can exhibit markedly contrasting migration programs. Here, we investigate the autumn migration of one Helopsaltes grasshopper-warbler from a population near Magadan, North East Russia, based on light-level geolocation. Although often considered to belong to Middendorff's Grasshopper-warbler H. ochotensis, recent genetic studies suggest that birds from this population are more closely related to Pallas's Grasshopper-warbler H. certhiola. We compare the migratory behavior of the Magadan bird with two Pallas's Grasshopper-warblers tracked from populations in the Kolyma River valley and the Amur region, Russia. We found similar migration patterns in all three tracked individuals, with stopover sites in eastern China and wintering sites in mainland Southeast Asia, within the known range for Pallas's Grasshopper-warbler. Furthermore, based on morphological data compiled during bird ringing, we were able to confirm the presence of potential "Magadan grasshopper-warblers" during spring and autumn migration in Thailand. Our scant data provide further evidence that Magadan Helopsaltes, notwithstanding their morphological resemblance to Middendorff's Grasshopper-warbler, constitute a population of Pallas's Grasshopper-warbler.

Range-wide breeding habitat use of the critically endangered Yellow-breasted Bunting Emberiza aureola after population collapse.

The population of the Yellow-breasted Bunting Emberiza aureola, a formerly widely distributed and abundant songbird of northern Eurasia, suffered a catastrophic decline and a strong range contraction between 1980 and 2013. There is evidence that the decline was driven by illegal trapping during migration, but potential contributions of other factors to the decline, such as land-use change, have not yet been evaluated. Before the effects of land-use change can be evaluated, a basic understanding of the ecological requirements of the species is needed. We therefore compared habitat use in ten remaining breeding regions across the range, from European Russia to Japan and the Russian Far East. We also assessed large-scale variation in habitat parameters across the breeding range. We found large variation in habitat use, within and between populations. Differences were related to the cover and height of trees and shrubs at Yellow-breasted Bunting territories. In many regions, Yellow-breasted Buntings occupied early successional stages, including anthropogenic habitats characterized by mowing, grazing, or fire regimes. We found that the probability of presence can be best predicted with the cover of shrubs, herbs, and grasses. Highest probabilities were found at shrub cover values of 40%-70%. Differences in habitat use along a longitudinal gradient were small, but we found strong differences across latitudes, possibly related to habitat availability. We conclude that the remaining Yellow-breasted Bunting populations are not limited to specific habitat types. Our results provide important baseline information to model the range-wide distribution of this critically endangered species and to guide targeted conservation measures.

Meteorological factors affecting refueling of European Robin (Erithacus rubecula) during migrations.

Weather ultimately affects avian migration. The significance of meteorological variables is relatively well known for flights of migrants and for departure/landing decisions at stopover sites. Success of migration greatly depends on storage of fat and body mass gain at stopovers; however, the influence of weather on refueling at stopovers is surprisingly poorly studied. We tested the hypothesis that body mass change of European Robins during their migratory stopovers is affected by meteorological factors (air temperature, precipitations, surface wind speed), along with other ecological variables. We used data on body mass change in 9743 individuals (5147in spring and 4587 in the fall) captured and recaptured within the same day on the Courish Spit of the Baltic Sea in 1994-2003. Fuel deposition rate in Robins was positively associated with air temperature and with higher amount of precipitation. Wind speed did not influence the refueling efficiency of our study species. Also, fuel deposition rate of Robins was affected by age (higher in adults than in first-year birds), negatively influenced by the number of conspecifics at stopover, influenced by the progress of the season (negatively in spring and positively in fall), and negatively influenced by initial energy reserves of migrants, when birds in poor energy condition were more likely to gain weight than birds with large fuel stores. This study shows that refueling of Robins on migration stopovers is substantially affected by meteorological factors that should be taken in to account for comprehensive understanding of stopover ecology and migration strategy of songbird migrants.

Nocturnal life of young songbirds well before migration.

In songbirds, nocturnal activity is believed to be a characteristic feature of migration. However, unlike experimental conditions where the onset of nocturnal restlessness is defined as a shift of activity leading up to the dark period, this behaviour has, until now, not been observed in natural conditions. Here we studied the nocturnal behaviour of radio-tagged juvenile Eurasian reed warblers (Acrocephalus scirpaceus) during the pre-migratory period. The birds started nocturnal flights at the age of 38 days, whereas migration did not commence until they were at least 50 days old. The birds left their natal site by nocturnal flights and repeatedly returned to it. Such shuttle movements suggest the existence of a previously unknown period of nocturnal activity. Motivation to perform such night flights gradually increases with age. We relate the function of these nocturnal pre-migratory flights to the development of a stellar compass, necessary for detecting the compass direction towards winter quarters and for the formation of a navigational target, which will be used during return (spring) migration.