Hummingbird Life Cycles

Incubation lasts about 14-16 days--perhaps as long as 21 days in cool weather--during which time the female Ruby-throated Hummingbird is on the nest for about 50-55 minutes out of each hour. When the chicks hatch, they are about 2cm long, altricial (naked), and with very short bills. For several days they are unable to generate their own body heat, so the female must deal with the conflict of gathering food for them while not being off the nest for long stretches. It is suspected the male with whom she mated allows her passage into his feeding territory, so she does not have to search far for food and her time off the nest is minimal. In RTHU, the male is not known to care for nestlings in any way.

When the female RTHU does leave the nest to forage, she collects nectar, pollen, and tiny insects in her crop and returns to the nest, where she regurgitates the energy-rich slurry into the mouths of the nestlings. By the third day after hatch, the chicks ...