1. Laboratory of Ornithology, Cornell University, Ithaca, NY 14850
2. Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14850
3. Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607
4. Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061