Ms. Ruby-throated Hummingbird does it all!
by Juanita N. Baker, Ph.D.
How exciting to spot a Ruby-throated Hummingbird flying into the tree, then find its tiny nest in the making on a branch overhanging the water. Then return week after week to see the full nesting/developmental process. Alice Horst captured it all!
Ruby-throated Hummingbirds do not form mating bonds. The males know their role well…in the spring, arriving at their breeding area, they establish a territory. His spectacular gorget (brilliantly ruby-red throat patch with narrow velvety black border) and its shiny green iridescent feathers are there for courtship displays. With humming tail feathers, he dives on either side of the female to attract her. If she then perches, this signals the male to continue rapid arcs before her to instantly attract her. She gives a beckoning call and adopts a ‘welcoming’ cocked tail-bowing posture, and he proceeds to mate. Then in these 10 minutes, his parenting role is complete, and off he goes to lure another female to mate.
Alone, the female does all the parenting, starting with nest-building in a deciduous tree. The tiny nest (don’t be deceived by the photos—the nest is just about an inch wide! Golf ball size!) is anchored securely around a curving branch with spider webs from 10-40 feet above the ground. Alice Horst’s careful documentation shows that, evidently, Ms. Hummingbird began building the nest at the end of March. She wove abundant green lichen on the outside and edged one side with red lichen – a touch of decoration? Nest building may take two weeks, or more as 4/8/22 does not look as complete as the future nest. But had she already laid two eggs and had begun incubating them? Usually, it takes two weeks to incubate the eggs.
Alice returned three weeks later to find a hatchling, and two days later, large fledglings barely fitting in the nest together. Hatchlings are born with naked skin before hairlike pinfeathers begin to grow. Their eyes open at about nine days old, when the female stops brooding (keeping the nestlings warm, covering them with her body). They begin to stretch their wings at 15 days old and fledge in the next 3-5 days. While adults feed mainly on nectar sources, the fledglings require that their mother provides them with insects that are high in protein.
In spring, returning from migration, female Hummingbirds do choose to reuse nests after refurbishing them. Females will often have a second brood in the same year. The abandoned nest awaits.