In Broad-tailed, R2 is predominantly bright green with a partial border of rufous along the edge of the outer vane and variable black at the tip. In juvenile female Rufous/Allen’s, R2 has rufous across the entire base or on both the inner and outer vanes divided by a stripe of green. On the fanned tail, the amount and distribution of rufous coloration is important but variable within as well as between species. Calliopes have even bigger heads, plus shorter bills, shorter tails, and broad, curved outer primaries distinctly different from either Broad-tailed or Rufous/Allen’s. Rufous and Allen’s are relatively compact, big-headed, and barrel-chested with tapered outer primaries that give the folded wing a scythe-like shape. Broad-taileds are long and relatively slim, with proportionally smaller heads, longer, often slightly decurved bills, longer wings and tails, and relatively broad primaries except for the outer two (P9-10). Shape is one of the first clues for quickly separating these doppelgangers. In fall migration, the similar plumages of juvenile female Rufous and Allen’s hummingbirds, female and juvenile male Broad-tailed Hummingbirds, and female and juvenile male Calliope Hummingbirds cause a lot of confusion, especially when they stray east of their usual migration routes. “Female-plumaged” Broad-tailed, Rufous/Allen’s, and Calliope hummingbirds are often confused with one another during fall migration.
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