Species-specific responses of farmland birds to overhead powerlines

Displacement and attraction effects caused by transmission powerlines on
bird species have been documented, but this topic remains underexplored in
the scientific literature. Here, we evaluated the impact of transmission
powerlines on bird species typical of open farmlands in the Mediterranean
region, focusing on five areas designated to protect farmland birds in
Southern Portugal. Using an impact-gradient design, we assessed how birds
responded to the proximity of transmission powerlines. Breeding bird data
were collected in 2021 and 2022. Our analysis revealed that, after
controlling for habitat effects, overall Bird Species Richness and
Grassland Bird Species Richness were not significantly influenced by the
distance to powerlines. However, species-specific negative effects were
observed for two farmland species: the little bustard (Tetrax tetrax) and
the calandra lark (Melanocorypha calandra), both showing displacement up
to 1 km from the powerlines. These findings indicate no evidence of
community-level effects on species richness and no evidence of attraction
to powerlines from farmland birds, but confirm species-specific
displacement effects, with some species negatively impacted by the
presence of the transmission powerlines. The little bustard, a species of
high conservation concern that is also highly susceptible to collision
with overhead powerlines, requires compensation for habitat loss due to
the avoidance effect caused by powerlines.