Seasonal Species Richness Maps (IMAGE) Cornell University Caption Seasonal species richness of nocturnally migrating passerine bird species within 333 urban areas located in the contiguous USA. Credit Frank La Sorte, Cornell Lab of Ornithology. Usage Restrictions For use with articles about this research. 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.