Reproduction

Female Anna's Hummingbird Calypte anna Credit: Gwen Harlow (Size: 57.26 kb)

Couple formation

When the reproductive period arrives, the male hummingbird signals his presence to the female with songs and aerial flights. The interested female remains perched immobile, not too far away, and then she too advertises her presence. The male goes to meet her, and mating takes place. The two birds then go their separate ways. Male hummingbirds are polygamous, mating with a number of females during the reproductive season. In most of the species observed, the male only associates with the female at mating time. All the responsibilities, such as building the nest, incubation and raising the young usually fall to the female.

Anna's Hummingbird Calypte anna Credit: Frank Leung (Size: 113.87 kb)

Reproductive season

The beginning of the reproductive season varies according to the species and region. As a general rule, the peak in reproduction occurs when flowers are the most abundant. The nesting period of North American hummingbirds usually extends from the spring to the end of summer, except for the Anna's Hummingbird (Calypte anna), which generally nests in the winter. The female of this species can incubate its eggs when the temperature is low and there is snow in the area. This early nesting period (from November to May) is explained as a strategy that allows the species to avoid competition with other hummingbird species in temperate zones, especially in the bush growth of the California coast.

Hummingbird nest Non identified Credit: Suzanne Demers (Size: 172.98 kb)

Nests

Among most hummingbirds, nest-building lasts from 5 to 10 days. The nests are tiny, most being cup-shaped. Some are a few centimetres from the ground; others are perched 10 or even 30 metres high in a tree. The location of a nest seems to be related to weather conditions and humidity. Some nests sit on a branch; others are in the fork of two branches. Some are in very unusual spots. Most Hermits attach their nests to hanging leaves for protection from the rain. Many hummingbirds decorate the outside walls of their nests with camouflage materials such as lichens and mosses found on trees and rocks. The nests are often made more solid with spider webs. To ensure insulation for the eggs, softer materials such as feathers and animal hair are normally used to line the inside of the nest.

Hummingbird nest Non identified Credit: Suzanne Demers (Size: 159.36 kb)

Egg-laying and incubation

The clutch of all hummingbirds is almost invariably two lacklustre, oval-shaped, white eggs. The eggs are tiny, about the size of a pea. Their weight varies from 0.4 g in the tiniest species to 1.4 g in the Giant Hummingbird. There is generally a two-day gap between the laying of the first and second eggs. Incubation usually begins after the laying of the second egg and lasts from 16 to 19 days. In some species studied, the female was observed incubating her eggs 75% to 90% of the day. The females seem to compensate for the lack of meals by reducing their body temperature from 41°C to about 32°C.

Ruby-throated Hummingbird Archilochus colubris Credit: Robert Hoge (Size: 220.28 kb)

Nestlings and parental care

Nestlings are practically naked and blind when they hatch. The female feeds them all day, at a frequency of twice an hour. She broods them until they are 7 to 12 days old. For the first 5 days, the nestlings' eyes stay closed. From day 6 to day 9, their eyes begin to open and feathers develop on their wings, tail and back. Beginning at day 10 until day 17 or 19, the feathers develop at a quicker rate. When they are fully developed, the chicks are capable of emitting begging calls. The fledglings remain in the nest for 23 to 26 days or even 30 to 40 days in the High Andes. The little ones continue to be fed by their mother after they have left the nest. During their first days out, they stay in a particular spot. When they begin to fly better, their mother extends the time intervals between visits and encourages them to follow her.