Bird electrocution on power lines is an important conservation problem that affects many endangered species. We surveyed 3,869 pylons in the Barcelona Pre-littoral Mountains (Catalonia, NE Spain) and collected 141 carcasses of electrocuted birds, mainly raptors and corvids. Univariate analysis indicated that metal pylons with pin-type insulators or exposed jumpers, with connector wires, located on ridges, overhanging other landscape elements, and in open habitats with low vegetation cover were the most dangerous. A logistic regression model indicated that the probability of a pylon electrocuting a bird was mainly related to pylon conductivity, distribution of the conductive elements on the cross-arms, cross-arm configuration, habitat, topography, whether the pylon was overhanging other landscape elements, and presence of rabbits (Oryctolagus cuniculus). We validated the predictive power of this model by using a random sample of 20% of all pylons surveyed. We found that bird mortality was aggregated mainly on pylons assigned a high probability risk by the model. Pylons included in the very high electrocution risk category (9.2%) accounted for 53.2% of carcasses, whereas pylons classified in the low electrocution risk category (54.5%) only accounted for 3.5% of mortality. Power companies employed this classification to prioritize the correction of 222 pylons by installing alternate cross-arms and suspended jumpers and isolating wires and jumpers. We evaluated the effectiveness of this mitigation strategy. A significant fall in the mortality rate on corrected pylons combined with the lack of any reduction in the mortality rate in a sample of 350 noncorrected pylons indicated that the model selected adequately the most dangerous pylons and that the applied correction measures were effective. Consequently, our strategy may be a useful tool for optimizing efforts and resources invested in solving the problem of bird electrocution.