Swainson's Thrush (IMAGE) U.S. National Science Foundation Caption A Swainson's thrush is fit with a radio transmitter. The birds travel some 600 miles across the Gulf of Mexico during migration. They use two main cues -- weather and fat -- to make their migration risk assessment. Credit Mauricio Andrada Usage Restrictions None License Licensed content 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.