Birds and Electric Lines (image) University of Pennsylvania Share Print E-Mail Caption A red-tailed hawk lands on a transmission tower. Raptors posed a threat to the power grid in Southern California in the 1920s because their excrement caused short circuits on the electrical lines. Credit Etienne Benson Usage Restrictions In context of reporting Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.