National Geographic : 1951 Aug
S Frozen Flight Reveals the Source of a Hummer's Sound Primary feathers of this male Broad-tail's wings taper at the tips, producing slots. Air fluttering through the openings results in a distinctive rattling whistle. Female Broad-tails, with normally shaped feathers, fly with a buzzing sound like other hummingbirds (page 248). S Mom's on Her Nest; All's Right with the World From defiantly cocked bill to rakishly tilted tail, this Broad-tail presented a picture of maternal devotion. Cameras and lights a foot away failed to disturb her slumber. Pushed from her nest, she flew briefly, then returned to warming tiny eggs (pages 247 and 248).