Usa "primary feather" in una frase

1. Typically, an old primary feather at about the middle of each wing is shed first, and then other primaries are shed in an alternating fashion on either side of the middle primary; at no time are all the primaries gone

2. For some reason--opinions vary as to whether the condition is due to a virus, genetics, a parasite, or perhaps a nutritional deficiency--the primary feathers don't develop fully, growing in either short or twisted