Characterizing the domestic-wild bird interface through camera traps in an area at risk for avian influenza introduction in Northern Italy

Abstract

Direct or indirect interactions between sympatric wildlife and poultry can lead to interspecies disease transmission. Particularly, avian influenza (AI) is a viral epidemic disease for which the poultry-wild bird interface shapes the risks of new viral introductions into poultry holdings. Given this background, the study hereby presented aimed to identify wild bird species in poultry house surroundings and characterize the spatiotemporal patterns of these visits. Eight camera traps were deployed for a year (January to December 2021) in 3 commercial chicken layer farms, including free-range and barn-type setups, located in a densely populated poultry area in Northern Italy at high risk for AI introduction via wild birds. Camera traps' positions were chosen based on wildlife signs identified during preliminary visits to the establishments studied. Various methods, including time series analysis, correspondence analysis, and generalized linear models, were employed to analyze the daily wild bird visits. A total of 1,958 camera trap days yielded 5,978 videos of wild birds from 27 different species and 16 taxonomic families. The animals were predominantly engaged in foraging activities nearby poultry houses. Eurasian magpies (Pica pica), ring-necked pheasants (Phasianus colchicus), and Eurasian collared doves (Streptopelia decaocto) were the most frequent visitors. Mallards (Anas platyrhynchos), an AI reservoir species, were observed only in a farm located next to a fishing sport lake. Time series analysis indicated that wild bird visits increased during spring and winter. Farm and camera trap location also influenced visit frequencies. Overall, the results highlighted specific species that could be prioritized for future AI epidemiological surveys. However, further research is required to assess their susceptibility and infectivity to currently circulating AI viruses, essential for identifying novel bridge hosts.

Keywords: BRIDGE HOST; camera-trap survey, poultry farm, avian influenza, domestic-wild bird interface.

Figure 1

Schematic representation of Farm 1, 2, and 3. The red circles represent the camera trap locations (A to H). The figure also indicates the positions of poultry houses, chicken manure collection areas, and feed silos for each farm. Map realized with QGIS software (version 3.26).

Figure 2

A selection of wild bird species observed in the poultry farms studied (A to F) and overall wild bird visits detected per month (G). (A) Eurasian magpie (Pica pica), (B) European jackdaw (Corvus monedula), (C) Eurasian-collared dove (Streptopelia decaocto), (D) wood pigeon (Columba palumbus), (E) wild pheasant (Phasianus colchicus), (F) and a male (right) and female (left) mallards (Anas platyrhynchos). (G) Number of wild birds per species per month detected by camera traps on the 3 farms studied.

Figure 3

Activity patterns (relative frequency by time) of selected wild bird species visiting the poultry farms studied. (A) Common blackbird (Turdus merula), (B) white wagtail (Motacilla alba), (C) Eurasian magpie (Pica pica), (D) Western jackdaw (Corvus monedula), (E) Eurasian collared dove (Streptopelia decaocto), (F) European turtle dove (Streptopelia turtur), (G) mallard (Anas platyrhynchos), and (H) cattle egret (Bubulcus ibis).

Figure 4

Behaviors displayed by selected wild bird species during the period of study as recorded by camera traps placed in the 3 laying-hen farms.

Figure 5

Three-month rolling averages of daily wild birds’ visits throughout the period studied (camera traps at location A to E, G, and H). (A) Overall daily counts for Farms 1, 2 and 3; (B) Daily counts displayed separately for the 3 farms (Farm 1, light blue line; Farm 2, magenta line; Farm 3, green line). Color-coded arrows indicate peaks of wild bird observations.

Figure 6

Seasonality of wild birds’ visits to the studied laying-hen farms. (A) Seasonal mean detection rates of daily counts of wild birds visiting the 3 poultry farms studied. Farm 1, blue circle; Farm 2, magenta square; Farm 3, green triangle. (B) Correspondence analysis plot between Passeriformes, Galliformes, and Columbiformes and months of the year.

Figure 7

Behaviors displayed by wild birds in the outdoor area of Farm 2 as recorded by the camera trap.