Northern Mockingbird Song (AUDIO) Duke University Your browser does not support the audio element. Caption Researchers at the National Evolutionary Synthesis Center (NESCent), the Cornell Lab of Ornithology and McGill University suspect that inconsistent climates may play a role in the complexity of bird songs. Here, a sample of a Northern Mockingbird from the Macaulay Library of Natural Sounds at Cornell. Credit Cornell Laboratory of Ornithology, Macaulay Library of Natural Sounds Usage Restrictions Must include credit: Cornell Laboratory of Ornithology, Macaulay Library of Natural Sounds 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.