How farmland birds react to traffic noise?

The effect of vehicle noise on farmland birds living in the vicinity of very busy roads was investigated. The study was conducted on two plots of crop fields located near national roads Nr. 12 and 19, the most important trunk roads in Poland and the eastern part of the Europe. The results of the current study are of wide relevance because crop fields are the dominant landscape type in both Poland and Europe. The conservation of the animals, including birds, living in such habitats is a priority issue in view of the strong pressure from human activities and the intensification of agriculture. The fieldwork was carried out in monthly from April to June 2020 and included counting birds in three rows of listening-observation points situated at 50, 150 and 250 m from the roads. At each observation point, all farmland and meadow birds seen and heard during a five-minute period were recorded, as was the maximum ambient noise level during this time. With increasing distance from the roads, the level of noise decreased while the number of individual birds and observed species increased. Most of the birds recorded, like skylark, lapwing, whinchat, yellowhammer, meadow pipit, pheasant, and common quail, avoided the vicinity of the roads. In contrast, the abundant yellow wagtail appeared to be insensitive to traffic noise and was evenly distributed over the two study plots. The roads and their associated traffic noise had a negative impact over a distance of about 100 m. At that distance, noise levels above 53–60 dB led to sharp falls in bird densities. Bird mortality due to collisions with vehicles was low because noise combined with the lack of attractive roadside habitats effectively deterred birds from the vicinity of the roads.