What event, considered to be a birders principal meeting in South America, is held every orbital period of the Earth moving in its orbit around the sun?
South American Bird Fair: The South American Birdwatching Fair is an annual event for birdwatchers, held every year in a different country of the continent. South American Bird Fair:  It is described as the birder's principal meeting in South America, with people from all the world. Year: A year is the orbital period of the Earth moving in its orbit around the Sun.
South American Birdwatching Fair