1. Eurasian subspecies of tundra swan; smaller than the whooper
   - Bewick's swan

Type of: Cygnus columbianus, tundra swan

• obsequy
• observable
• observably
• observance
• observant
• observantly
• observation
• observation dome
• observation post
• observation station
• observation tower
• observational
• observator
• observatory
• observe
• observed
• observed fire
• observer
• observer's meridian
• observing
• observingly
• obsess
• obsessed
• obsession
• obsessional