Do little songbirds spread bird flu?
Basically, no, they don't.
Here for the very interested, from a paper in preprint stage:
"Among potential high-risk host taxa, abundance index of
Aythyini had the highest average importance in period B models... Other taxa had predictive effects with different annual lags e.g., breeding populations of
Anatidae and migratory populations of
Ardeidae and
Anserinae affecting later seasons ... we expect risk to be associated with proximity to coastlines, low elevations, low temperatures, and presence of high-risk waterbirds ... Our risk projections point to an increased risk of HPAI presence in northwest Europe, particularly around the North Sea coast, associated with the emergence of the H5N1 genotype of clade 2.3.4.4b... This shift in geographical burden of risk appears to be driven by differing importance of climate, geography, and abundance of specific bird taxa (
Anatinae,
Anserinae,
Ardeidae, and
Aythyini) at different calendar times and with different seasonal lags ...highlighting the association between both temperature-driven waterbird movements and congregation of waterbirds at the zero-degree isotherm and the distribution and spread of HPAI... Among host taxa we explicitly modelled, relative abundance of
Anatinae (dabbling ducks) was the most consistent predictor of HPAI presence, followed by
Aythini (pochards),
Anserinae (swans and geese), and
Ardeidae (herons). Except for
Ardeidae, these taxa are generally considered maintenance hosts of avian influenza as part of the Anseriformes... Mallards within the
Anatidae appear to be effective carriers as they may experience only mild disease, even when infected with H5N1 clade 2.3.4.4b ... we did not detect any association between abundance of Charadriiformes hosts (
Laridae (gulls),
Arenaria (turnstones), or
Calidris (sandpipers)) and HPAI presence. This suggests that while gulls and shorebirds have experienced unprecedented infection and die-offs, they may not have driven the precise spatial dynamics of HPAI clade 2.3.4.4b in Europe.... birds with specific diets and foraging behaviours showed varying and highly localised trends in risk... faecal-oral transmission primarily occurs through viral shedding into water. However, studies looking at viral shedding of HPAI including clade 2.3.4.4b viruses have reported high levels of additional shedding via the respiratory system. We find a somewhat unexpected importance of scavenging and predation behaviour in both modelled periods. Combined with the high reported rates of cross-species transmission to predatory birds such as owls and raptors, this indicates the role of predation in spatial transmission should not be ignored."
https://www.biorxiv.org/content/10.1101/2024.07.17.603912v2.full