Stable Isotope Analysis Reveals Common Teal (Anas crecca) Molting Sites in Western Siberia: Implications for Avian Influenza Virus Spread

Abstract

The wetlands of southwestern Siberia (SWS) are a crossroads of bird migration routes, bringing avian influenza (AIV) strains that were previously isolated in different regions of the continent to Siberia. It is known that Anseriformes that breed in SWS migrate for the winter to central Hindustan or further west, while their migration routes to southeast Asia (SEA) remain unconfirmed. Here, we mapped the molting sites of the migrating Common Teals (Anas crecca) via analyzing stable hydrogen isotope content in feathers of hunters' prey and supplemented the analysis with the genetic structure of viruses isolated from teals in the same region. Post-breeding molt of autumn teals most likely occurred within the study region, whereas probable pre-breeding molting grounds of spring teals were in the south of Hindustan. This link was supported by viral phylogenetic analysis, which showed a close relationship between SWS isolates and viruses from south and southeast Asia. Most viral segments have the highest genetic similarity and the closest phylogenetic relationships with viruses from teal wintering areas in southeast Asian countries, including India and Korea. We assume that the winter molt of SWS breeding teals on the Hindustan coast suggests contacts with the local avifauna, including species migrating along the coast to SEA. Perhaps this is one of the vectors of AIV transmission within Eurasia.

Keywords: Anas crecca; avian influenza; common teal; isoscape; migration routes; molting grounds; stable isotopes.

Figure 1

Possible post-breeding molting areas for Common Teal (Anas crecca) captured in western Siberia during fall migration, determined by SIA and by ring recoveries according to Veen et al. [28]. Common Teal area data are taken from [54].

Figure 2

Wintering area for Common Teal (Anas crecca) captured in spring in Western Siberia, determined by SIA and by ring recoveries according to Veen et al. [28]. Common Teal area data are taken from [54].

Figure 3

Maximum likelihood phylogenetic tree of HA segment of seven H3N8 AIVs isolated from Common Teals in western Siberia (marked green). The blue circle symbol indicates branches with values SH-aLRT > 80% and UFboot > 95%. The color markings on the right indicate the time of sample collection (red is the summer nesting period, blue is the winter wintering period).