Tuesday, May 21, 2013

Rufous Hummingbird

Rufous Hummingbird - Selasphorus rufus

The first garden hummingbird this season was a female Rufous Hummingbird that was attracted to a clematis.  The flowers were not out, which confused me until I saw the bird grab a "cotton ball" mass of fluffy seeds from the blooms of the prior year. The soft seeds will line the cup of the nest. 
Insects are a principle food source. The insects inside the tubular flowers are sucked up with the nectar. The Rufous Hummingbird also catches insects on the wing from a perch, much like the flycatchers. These birds are also known to use the wind of their wings to disturb leaves on the ground, which exposes insects underneath. 

The iridescence of the feathers on the gorget is amazing. The feather structure amplifies specific wavelengths of light and only reflects the light directly ahead of the bird. 
The feathers do not lie flat and are raised upward at an angle with a v-shaped trough that runs along each barb. The iridescent surface is precisely positioned so that it reflects light directly ahead. Within the iridescent surface of the barbule are layers of microscopic discs, each filled with tiny air bubbles. Each disc has an optical thickness of half the wavelength of the reflected color. Light of the"correct" wavelength is "added together" and light of other wavelengths is canceled out. 


The Atlas of Breeding Birds of Alberta. Federation of Alberta Naturalists. 2007.

Baicich PJ, Harrison CJO. Nests, Eggs, and Nestlings of North American Birds. Princeton UP. 2005.

Fisher C, Acorn J. Birds of Alberta. Lone Pine Publishing. Edmonton. 1998.

Sibley David A. The Sibley Guide to Bird Life & Behavior. Alfred A Knopf, Inc. New York. 2001.

Tudge Colin. The Bird. Crown Publishers. New York. 2008.

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