Hummingbird Nest

Birds' nests are some of the most intricate, strong and beautiful structures found in nature.  They range in design from little more than a divot in the earth to elaborate mud condos and woven wonders, from enormous stick platforms to diminutive, delicate cups.  Nests of North and South America's hummingbirds are among the smallest nests found in the world.


While out for our daily walk a few weeks ago, I happened to look down at just the right moment and was delighted to find a hummingbird nest on the ground.  The nest was below a eucalyptus tree that is frequented by Anna's Hummingbirds (Calypte anna), and this nest almost certainly was built by a member of that species.  Presumably, the nest fell out of the tree before it served its purpose of housing young, as a used nest would be flattened (and soiled) from the rapid growth of the little birds inside.  Nonetheless, I was excited by this discovery, since I have long wanted to closely examine a hummingbird nest, and they are quite difficult to find!  

 
At the beginning of the breeding season, which can start as early as December in California, the female Anna's Hummingbird chooses a location for her nest.  Nests are typically placed on horizontal branches of trees or shrubs, usually between 6 and 20 feet above the ground, near a source of nectar.  Eucalyptus trees are a favorite for nesting hummingbirds, and the introduction of this tree across California has contributed to the spread of the Anna's Hummingbird.  Construction of the nest is undertaken by the female alone, and takes about a week.


Nests are constructed of plant down (such as willow, cattail or thistle fluff) and small feathers, bound together by spider silk.  The outside of the nest is covered with a layer comprised of miniscule fragments of bark, lichen and moss.  This serves to camouflage the nest.  From below, a nest is hidden by the horizontal branch on which it sits; from above, it is obscured by leaves; and from the side, it is designed to look like no more than a knot on a branch. 

To construct the nest, the female hummingbird creates a platform on her chosen branch, sits on it and builds the nest cup up around her.  Nests of Anna's Hummingbirds measure about one inch high and 1.5 inches in diameter; the nest pictured here was found slightly flattened.


Anna's Hummingbirds raise two or even three broods of young during a breeding season.  Each time, the female lays a clutch of two very small, white eggs.  Each egg is about 0.5 inches long and 0.3 inches wide, roughly the size of a jelly bean.  The female incubates her eggs for 14 - 16 days, after which the young hatch.  At the time of hatching, the young hummingbirds are naked and helpless, their eyes sealed shut.  The female feeds her young a regurgitated mixture of tiny insects and nectar by inserting her bill deep into their mouths.  The young remain in the nest, growing quickly, for just 20 days before fledging.

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