Asymptomatic infection with highly pathogenic avian influenza H5N1 in wild birds: how sound is the evidence?

BACKGROUND: Widespread deaths of wild birds from which highly pathogenic avian influenza virus H5N1 has been isolated suggest that the virus continues to be lethal to them. However, asymptomatic carriage by some wild birds could allow birds to spread the virus on migration. Confirmation of such carriage is therefore important for the design of mitigation measures for the disease in poultry. DISCUSSION: Two recent papers have reported the isolation of H5N1 from a small number of water birds in China and Russia and have concluded that wild birds can spread the viruses over long distances on migration. However, both papers contain weaknesses in the provision of ornithological and associated data that compromise conclusions that can be reached about the role of wild birds in the spread of H5N1. We describe the weaknesses of these studies and highlight the need for improved methodological description and methodology, where appropriate, and further research. SUMMARY: A rigorous assessment of whether wild birds can carry H5N1 asymptomatically is critical to evaluating the risks of spread by migratory birds on long-distance migration

Attempted re-establishment of a sooty tern Onychoprion fuscatus breeding colony on Denis Island, Seychelles

Seychelles supports around three million nesting pairs of sooty terns. However, there have been recent declines and the colonies continue to face ongoing threats from habitat change and excessive commercial harvesting of their eggs, as well as potential threats by commercial fishing and climate change. A possible method to counter these threats is to re-establish breeding colonies on islands from which they have disappeared. An attempt was made to attract birds to a previously occupied island through habitat management, decoy birds and playback of recorded sooty tern calls. Habitat preparation involved predator eradication and tree removal to provide open ground with bare sandy areas and low herb vegetation. Overflying birds were attracted by broadcast calls, with some circling over and landing among the decoys. Large three-dimensional plastic models were superior to other models presented. This study demonstrated that large numbers of birds can be attracted by these means and that the birds then undertook behaviour associated with breeding, including egg laying by a few birds. However, after five seasons a breeding colony has not yet been established; one possible cause is the emergence of unexpected egg predators, common moorhen Gallinula chloropus and common myna Acridotheres tristis

Tracking seabird migration in the tropical Indian Ocean reveals basin-scale conservation need

Summary Understanding marine predator distributions is an essential component of arresting their catastrophic declines.1,2,3,4 In temperate, polar, and upwelling seas, predictable oceanographic features can aggregate migratory predators, which benefit from site-based protection.5,6,7,8 In more oligotrophic tropical waters, however, it is unclear whether environmental conditions create similar multi-species hotspots. We track the non-breeding movements and habitat preferences of a tropical seabird assemblage (n = 348 individuals, 9 species, and 10 colonies in the western Indian Ocean), which supports globally important biodiversity.9,10,11,12 We mapped species richness from tracked populations and then predicted the same diversity measure for all known Indian Ocean colonies. Most species had large non-breeding ranges, low or variable residency patterns, and specific habitat preferences. This in turn revealed that maximum species richness covered >3.9 million km2, with no focused aggregations, in stark contrast to large-scale tracking studies in all other ocean basins.5,6,7,13,14 High species richness was captured by existing marine protected areas (MPAs) in the region; however, most occurred in the unprotected high seas beyond national jurisdictions. Seabirds experience cumulative anthropogenic impacts13 and high mortality15,16 during non-breeding. Therefore, our results suggest that seabird conservation in the tropical Indian Ocean requires an ocean-wide perspective, including high seas legislation.17 As restoration actions improve the outlook for tropical seabirds on land18,19,20,21,22 and environmental change reshapes the habitats that support them at sea,15,16 appropriate marine conservation will be crucial for their long-term recovery and whole ecosystem restoration

Biological Earth observation with animal sensors

Space-based tracking technology using low-cost miniature tags is now delivering data on fine-scale animal movement at near-global scale. Linked with remotely sensed environmental data, this offers a biological lens on habitat integrity and connectivity for conservation and human health; a global network of animal sentinels of environmen-tal change

Control or eradication: Problems in the management of invasive birds

Humans have captured, transported and intentionally released wild birds for centuries (Blackburn et al., 2009). Motivations for such purposeful introductions include food (West and Zhou, 2007), religion (Agoramoorthy and Hsu, 2007), sport (McDowall, 1994), biocontrol (Bennett and Hughes, 1959; Kurdila, 1995) and aesthetics (Ryan, 1906; Thomson, 1922). Many purposeful bird introductions were the work of acclimatization societies, particularly in North America, New Zealand and Australia. These societies were formed in the 19th century by European settlers to transport bird species from their homelands in efforts to establish them in the newly settled regions (Thomson, 1922; Dunlap, 1997). As a result of these efforts, the Common or European Starling (Sturnus vuigaris), the House Sparrow (Passer domesticus) and many other species are now permanently established far beyond their native ranges. Commercial trade in captive birds is also an important introduction pathway. Non-native species are introduced through unintentional releases of cage birds and inadvertent escapes from research facilities, zoos and private collections. The international bird trade has declined gradually following adoption in the USA of the 1992 Wild Bird Conservation Act and similar European regulations restricting trade in wild birds following the westward spread from China of the highly pathogenic H5Nl avian influenza virus in the early 2000s (Cooney and Jepson, 2006). The pattern of trade in wild birds has also changed. Mexico and Asia have replaced the USA and the European Union as the principal importers in the global cage-bird market (Cardador et al., 2017; Hobson et al., 2017). Nevertheless, large-scale traffic in wild and captive-bred birds continues. During the 3-year period 2000-2002, global ~orts of live birds totalled 3,640,135 compared with 807,476 during 2015-2017 according to the Convention on International Trade in Endangered Species (GTES, 2018). Invasive birds have major impacts throughout the world, regardless of the invasion pathway. Pimentel et al. {2001) examined the published data available on invasive species in the USA, the UK, Australia, South Africa, India and Brazil. They concluded that introduced birds were responsible for US$2.4 billion in damage to agriculture, human health and natural resources among these six countries. We focus in this chapter on a subset of these impacts, namely the threats that invasive birds pose to native species and the efforts that have been made to reduce or eradicate such impacts. Specifically, we review management options and control strategies, explore what has and has not been effective, and discuss case histories of success and failure

THE STARLING IN EUROPE: MULTIPLE APPROACHES TO A PROBLEM SPECIES

In Europe, Starlings are widely distributed and comprise both resident and migrant populations. These cause various kinds of damage which varies with the crops grown in different European Economic Community (EEC) countries. Although EEC member states are governed by the same legislation on bird protection, each state interprets the Community legislation in its own national legislation. This leads to different national approaches to the prevention of Starling damage, with little information exchange between member states. The establishment of an EEC (or wider) working group on bird pests is recommended to coordinate research and development

Synchrony of primary moult in pairs of Common Mynas Acridotheres tristis

Volume: 135Start Page: 185End Page: 18

The turtle doves of Bird Island, Seychelles

Volume: 115Start Page: 206End Page: 21