Vertical space utilization by urban birds and their relationship to electric poles and wires

Birds living in urban areas use various human-made structures. Many artificial structures such as houses, electric poles, and electric wires are used as “perches”. The height of urban birds (vertical space utilization) may be affected by the height of these structures are. We investigated how and which height birds utilize in the urban space in Hakodate City in Hokkaido, and whether they are related to the electric poles and wires. A decision tree was constructed to analyze how differences in species (Tree Sparrow, Rock Dove, Carrion Crow, Large-billed Crow, and Slaty-backed Gull.), seasons, and in the numbers of high-rise buildings explained the observed heights of birds in the following three categories; L-zone (0–4.8 m), E-zone (4.8–14.5 m), and H-zone (all ranges higher than 14.5 m). The combination of explanatory variables that were strongly related to height differed among species. Although Carrion Crows and Tree Sparrows most frequently used heights with electric poles and wires, their usage patterns were different. For both species, the E-zone was used not only as merely a perching place but also as an important place where behaviors related to reproduction were exhibited. Knowing the vertical space utilization of birds in urban areas may help avoid future accidents involving unmanned aerial vehicles.