Transatlantic spread of highly pathogenic avian influenza H5N1 by wild birds from Europe to North America in 2021

Highly pathogenic avian influenza (HPAI) viruses of the A/Goose/Guangdong/1/1996 lineage (GsGd), which threaten the health of poultry, wildlife and humans, are spreading across Asia, Europe and Africa, but are currently absent from Oceania and the Americas. In December 2021, H5N1 HPAI viruses were detected in poultry and a free-living gull in St. John, Newfoundland and Labrador, Canada. Phylogenetic analysis showed that these viruses were most closely related to HPAI GsGd viruses circulating in northwestern Europe in spring 2021. Analysis of wild bird migration suggested that these viruses may have been carried across the Atlantic via Iceland, Greenland/Arctic or pelagic routes. The here documented incursion of HPAI GsGd viruses into North America raises concern for further virus spread across the Americas by wild bird migration.

[A brief history about the ALPI project]

[Conceived by the National Ringing Centre ISPRA and MUSE (Trento, formerly MTSN), the Alps Project was launched in 1997 in order to understand the post-breeding migration strategies of birds across the Italian Alps. The project is realized thanks to the support offered by MUSE and several institutions at a local scale, not to mention the collaboration of over one hundred ringers. In more than twenty years, 40 stations located in sites of passage (alpine and pre-alpine passes) and stop-over (valley floors and slopes) have taken part in the project, leading to a dataset of 666,471 ringed individuals and 191 species (as to 2017). After a first exploratory phase (1997-2002), in which the migration was investigated in its many aspects of specific composition and spatial-temporal variation, the project has been restricted to a smaller number of stations since 2007. Those stations are characterized by working in a standardized and continuous way during the whole period (August-November) or during the migration period of the intra-Palearctic species (end of September-October). In this paper we describe the aims, protocols and organizational aspects of the project, with a special focus on monitoring trends and changes in the long-term phenology. This ongoing project (2021) is part of the ISPRA national ringing plan to monitor bird migration across the country]. [Article in Italian]

Temporal trends in abundance and phenology of migratory birds across the Italian Alps during a 20-year period

Introduction: Bird migration across mountainous regions has been studied usually at single sites due to the difficulty in employing and support a multi-site sampling effort. This may affect inference on migration whose scale is larger that a single site. The Progetto Alpi has been monitoring post-breeding bird migration through the Italian Alps with a network of several ringing stations since 1997. Until 2017, 666,471 ringing data of 191 different species were collected. Methods: Phenology of bird migration in terms of date of capture and the related elevational distribution during the sampling season (August-November) were analysed for 69 species. For a subset of 45 species the inter-annual variation in phenology along with trends in the number of ringed birds and in the ratio between the number of juveniles and adults ringed, were also analysed. Results: Migration through the Italian Alps occurred differently between species, with heterogeneity across species in the median date of capture and their elevational distribution. No linear trends in phenology were detected. For four species an annual linear increase of the ringed individuals was detected, while for other four species an annual linear decrease of the captures was detected. For two species, an increase of the ratio between the number of the juveniles and the number of adults ringed was detected. Conclusions: The long-term standardized monitoring of post-breeding migration allowed us to consolidate and increase knowledge of bird migration through Italian southern Alps. The information gathered allowed us to define the temporal and elevation distribution of passerine birds crossing the mountainous area, and to test interannual trends in the number of captures. The main purpose of this work was to report on the information collected in twenty years of field activity, providing a contribution to the understanding this complex phenomenon. Further investigations and more in-depth analyses are necessary to understand how environmental factors and species-specific eco-physiological traits interact and affect migratory strategies of passerine birds in the Italian Alpine region.

Continental patterns of bird migration linked to climate variability

For ˜100 years, the continental patterns of avian migration in North America have been described in the context of three or four primary flyways. This spatial compartmentalization often fails to adequately reflect a critical characterization of migration — phenology. This shortcoming has been partly due to the lack of reliable continental-scale data, a gap filled by our current study. Here, we leveraged unique radar-based data quantifying migration phenology and used an objective regionalization approach to introduce a new spatial framework that reflects interannual variability. Therefore, the resulting spatial classification is intrinsically different from the “flyway concept”. We identified two regions with distinct interannual variability of spring migration across the contiguous U.S. This data-driven framework enabled us to explore the climatic cues affecting the interannual variability of migration phenology, “specific to each region” across North America. For example, our “two-region” approach allowed us to identify an east-west dipole pattern in migratory behavior linked to atmospheric Rossby waves. Also, we revealed that migration movements over the western U.S. was inversely related to interannual and low-frequency variability of regional temperature. A similar link but weaker and only for interannual variability was evident for the eastern region. However, this region was more strongly tied to climate teleconnections, particularly to the East Pacific-North Pacific (EP-NP) pattern. The results suggest that oceanic forcing in the tropical Pacific—through a chain of processes including Rossby wave trains—controls the climatic conditions, associated with bird migration over the eastern U.S. Our spatial platform would facilitate better understanding of the mechanisms responsible for broad-scale migration phenology and its potential future changes.

Animal Migration Patterns Extraction Based on Atrous-Gated CNN Deep Learning Model

Weather radar data can capture large-scale bird migration information, helping solve a series of migratory ecological problems. However, extracting and identifying bird information from weather radar data remains one of the challenges of radar aeroecology. In recent years, deep learning was applied to the field of radar data processing and proved to be an effective strategy. This paper describes a deep learning method for extracting biological target echoes from weather radar images. This model uses a two-stream CNN (Atrous-Gated CNN) architecture to generate fine-scale predictions by combining the key modules such as squeeze-and-excitation (SE), and atrous spatial pyramid pooling (ASPP). The SE block can enhance the attention on the feature map, while ASPP block can expand the receptive field, helping the network understand the global shape information. The experiments show that in the typical historical data of China next generation weather radar (CINRAD), the precision of the network in identifying biological targets reaches up to 99.6%. Our network can cope with complex weather conditions, realizing long-term and automated monitoring of weather radar data to extract biological target information and provide feasible technical support for bird migration research.

Birds with multiple homes. The annual cycle of the pallid swift (Apus pallidus brehmorum)

We tracked pallid swifts (Apus pallidus brehmorum) from a single breeding colony in Gibraltar over two years. Our results show movement of birds between specific regions within the non-breeding geographical area at specific times of the year. The tracking of a single individual showed remarkable fidelity to the areas visited between years. Furthermore, two pallid swifts tracked over the entire eight-month non-breeding period, while in Africa, gave no indication of coming to land, supporting previous findings of an airborne existence in swifts outside the breeding season. In addition, the crossing of the Sahara Desert to and from breeding grounds is remarkably fast, with one individual crossing it in just over a day. We discuss our findings in the context of bird migration evolutionary strategies.

Ecological Tourism Opportunities in the Area of Ognyanovo Dam

The dam of Ognyanovo is located in the Eastern Sofia Plain, only 40 km awayfrom the capital of Bulgaria. It is one of the country’s most beautiful places – full of biodiversity,especially as regards avifauna species. An important factor which makes the dam a special object ofscientific and tourist interest is its location on one of the main bird migration routes: the ViaAristotelis.For three consecutive years, the area’s fauna potential has been studied andsignificant biodiversity has been identified.This study aims to explore the opportunities for ecotourism development there.

Birds of three worlds: moult migration to high Arctic expands a boreal-temperate flyway to a third biome

Background Knowledge on migration patterns and flyways is a key for understanding the dynamics of migratory populations and evolution of migratory behaviour. Bird migration is usually considered to be movements between breeding and wintering areas, while less attention has been paid to other long-distance movements such as moult migration. Methods We use high-resolution satellite-tracking data from 58 taiga bean geese Anser fabalis fabalis from the years 2019–2020, to study their moult migration during breeding season. We show the moulting sites, estimate the migratory connectivity between the breeding and the moulting sites, and estimate the utilization distributions during moult. We reveal migration routes and compare the length and timing of migration between moult migrants and successful breeders. Results All satellite-tracked non-breeding and unsuccessfully breeding taiga bean geese migrated annually to the island of Novaya Zemlya in the high Arctic for wing moult, meaning that a large part of the population gathers at the moulting sites outside the breeding range annually for approximately three months. Migratory connectivity between breeding and moulting sites was very low (rm = − 0.001, 95% CI − 0.1562–0.2897), indicating that individuals from different breeding grounds mix with each other on the moulting sites. Moult migrants began fall migration later in autumn than successful breeders, and their overall annual migration distance was over twofold compared to the successful breeders. Conclusions Regular moult migration makes the Arctic an equally relevant habitat for the taiga bean goose population as their boreal breeding and temperate wintering grounds, and links ecological communities in these biomes. Moult migration plays an important role in the movement patterns and spatio-temporal distribution of the population. Low migratory connectivity between breeding and moulting sites can potentially contribute to the gene flow within the population. Moult migration to the high Arctic exposes the population to the rapid impacts of global warming to Arctic ecosystems. Additionally, Novaya Zemlya holds radioactive contaminants from various sources, which might still pose a threat to moult migrants. Generally, these results show that moult migration may essentially contribute to the way we should consider bird migration and migratory flyways.