Our August question was a hard one, I thought:

Which breeding landbird of the eastern US and Canada molts its primaries in the sequence 1-2-3-4-5-6-7-8-10-9?

But not too hard for Grant McCreary or for this month’s winner, Dick Cannings, both of whom identified Ruby-throated Hummingbird as the species in question.

And why do ruby-throats (and other hummingbirds) shed their wing feathers in such an odd sequence? We’ll let Steve Howell, author of the new (and wonderful) Peterson Reference Guide to Molt in North American Birds answer that one:

“Because P9 is the largest and heaviest primary, precision flight might be compromised if P9 were shed first, when P10 could be quite worn. Thus replacing P10 first provides more support for the growth of P9.”

Watch for our new question in the September WINGS e-newsletter!