1. Hawk Mountain Sanctuary, Orwigsburg, PA, USA
2. Natural Heritage Program, Maryland Department of Natural Resources, Annapolis, MD, USA
3. Ned Smith Center for Nature and Art, Millersburg, PA, USA
4. Prince Edward Point Bird Observatory (retired), Picton, Prince Edward County, ON, Canada
5. Explos-Nature, Observatoire d'oiseaux de Tadoussac, Les Bergeronnes, QC, Canada