Warbler with Geolocator Backpack (image) Penn State Share Print E-Mail Caption Blue winged warbler with a geolocator, essentially a backpack with light sensors. Credit Gunnar Kramer, University of Toledo Usage Restrictions Credit must be provided alongside image. 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.