Hummingbirds are among the smallest birds, and their nesting behavior is a remarkable feat of natural engineering. The female manages the entire process of building a nest and raising young, a solitary effort that begins with precise timing. This timing is not fixed, but is a dynamic response to environmental conditions, particularly the availability of food sources. Factors like local climate, the specific species, and the abundance of nectar and insects determine when nest building begins.
When Hummingbirds Begin Building
Nest construction typically begins immediately after the female has mated, coinciding with the first period of stable, warm weather in the spring. For migratory species like the Ruby-throated Hummingbird, this usually means starting to build shortly after their return from wintering grounds, generally in April or May. The initiation of building is closely tied to the peak bloom of nectar-producing flowers, which provides the necessary fuel for egg production and chick rearing.
The female scouts potential locations and gathers materials as soon as she establishes a territory rich in food. This early start ensures that the nest is ready for eggs during the most resource-abundant part of the season.
A female may raise multiple broods in a single season if conditions remain favorable. For successive broods, she often builds a completely new nest for each attempt, sometimes starting construction before the young from the previous brood have fully fledged.
Construction: Materials and Location Selection
The nest is a minuscule, cup-shaped structure, often no larger than a walnut or a thimble. It is crafted exclusively by the female from lightweight, pliable materials collected from the environment. Plant down and soft fibers form the interior lining that cushions the eggs.
The exterior is meticulously camouflaged with bits of lichen, moss, and bark flakes, applied to help the structure blend seamlessly with the branch. To hold the assembly together and anchor it securely to a thin branch, the female uses spider silk.
This silk acts as a flexible, natural glue, allowing the nest to stretch outward as the nestlings grow larger. Nest placement is highly selective, usually in a forked tree branch or shrub between 10 and 20 feet off the ground. The chosen site offers protection from wind and sun, often sheltered by overhanging leaves. The tiny size and the exterior camouflage make the finished nest difficult for predators and human observers to detect.
The Complete Nesting and Fledging Timeline
Once the female selects her location, the initial construction phase is fast, typically lasting between three and ten days. She then lays her eggs, always a clutch of two, each about the size of a navy bean. The eggs are laid one to two days apart, but incubation begins shortly after the first egg appears.
The incubation period lasts for approximately 14 to 22 days. Cooler temperatures can extend this period, requiring the female to sit tightly on the eggs to keep them warm.
After hatching, the young are born blind and nearly naked, relying entirely on the mother for warmth and food. The subsequent nestling period lasts between 18 and 28 days.
During this demanding phase, the female feeds the rapidly growing young a mix of nectar and tiny insects, regurgitated directly into their throats. The young birds must reach a near-adult size and develop flight feathers before they are ready to leave the nest. The total cycle, from the start of nest building to the young leaving the nest, can take five to eight weeks.
Regional and Species Variation
The timing of nest construction varies significantly across the geographic range of hummingbirds, reflecting local climate and species-specific adaptations. In the warmest parts of the United States, such as coastal California and Florida, resident species begin nesting much earlier than migratory counterparts. The Anna’s Hummingbird, a non-migratory species in the West, can start building as early as late December or January, taking advantage of mild winter temperatures.
Conversely, species that migrate long distances delay their nesting until their arrival in northern regions. For these birds, construction may not begin until May or even June in the northernmost parts of their range.
Unseasonable weather, such as an unexpected cold snap, can delay the start of construction or temporarily halt building activity. Altitude also plays a role, with hummingbirds at higher elevations often starting their nesting process later in the season.