Anna’s hummingbirds (Calypte anna) are small, iridescent birds found along the west coast of North America. The male Anna’s hummingbird has a striking rose-pink throat and crown, while the female has green feathers on the back and grey underparts. Anna’s hummingbirds are highly territorial and aggressively defend their feeding grounds from intruders. Like all hummingbirds, they have very high metabolisms and must feed frequently on nectar and small insects.
During breeding season, male Anna’s hummingbirds perform elaborate courtship displays to attract females. If successful, the female will build a small, compact nest out of plant down, spider webs, and lichens. She uses her body as a mold to shape the nest and binds the materials together with strands of spider silk. The nest building process is a demanding activity that requires significant time and energy investment from the female hummingbird.
Where do Anna’s Hummingbirds Nest?
Anna’s hummingbirds nest in a variety of habitats, both natural and human-made. Their nests are typically found in trees and shrubs, usually on a downward sloping twig. This allows the nest to be anchored firmly while partially hanging freely underneath the branch. Favorite nest sites include oak, sycamore, pine, and eucalyptus trees. Anna’s hummingbirds readily nest in gardens and backyards too, building their tiny nests in ornamental shrubs and trees.
The nest is usually situated 3-20 feet above ground. Lower placements may occur where tree cover is minimal. The female seems to prefer concealing the nest site behind foliage. Nest concealment likely reduces predation risks and provides shade and insulation from the elements. Sometimes Anna’s hummingbirds nest on wires, posts, or other man-made structures. They tend to avoid nesting very high up in trees, unlike some larger hummingbird species.
When does Nest Building Occur?
Anna’s hummingbirds breed between November and June in their typical range. They can raise up to 3 broods in a season depending on food availability. Nest building occurs in the weeks leading up to egg laying. The female does most of the construction work, though the male may make some minor contributions.
Fall and early winter nests are built between September and December. Anna’s hummingbirds get an early start on breeding compared to other backyard birds. Nesting in winter allows them to take advantage of winter-blooming flowers and less competition from insects for nectar resources.
Spring nests occur between late February and May, corresponding with the flowering of currants, gooseberries, manzanitas, and other shrubs. Summer nests happen from May through July during peak flower season.
Nest Construction Process
Anna’s hummingbird nest building happens in 5 general stages:
- Site selection
- Gathering materials
- Building the base
- Shaping the walls
- Finishing touches
Site Selection
The female Anna’s hummingbird chooses a nest site by herself in her breeding territory. She will spend up to a week surveying potential spots before settling on one. The female examines forked branches and vegetation at various heights before choosing a specific location. Good nest sites provide a combination of support, concealment, shade, and shelter from wind and rain.
Gathering Materials
Once a site is selected, the female starts collecting nest materials. She gathers cobwebs, tiny twigs, buds, lichens, bark fibers, petals, feathers, and downy plant seeds.Spider silk serves as the “glue” that binds everything together. The female hummer strips the silk from webs she finds or harvests it directly from the spider. Gathering trips may cover large distances as the female seeks specific materials.
Building the Base
The female hummingbird begins constructing the nest by laying down a base layer of plant down bound with spider silk. She uses lichens and bud scales first before adding softer plant down and feathers. The base takes shape as a tiny cup, providing the core structure.
Shaping the Walls
The female continues adding materials to build up the nest walls in concentric layers. Each layer gets slightly smaller, forming the compact, cup-shaped interior. The hummingbird uses her body as a mold, turning and compressing materials against her sides while working. The walls end up about 1.5 inches tall when complete.
Finishing Touches
In the final stage, the female hummingbird focuses on strengthening and insulating the nest. She binds the entire structure together with more silk and decorates the exterior with lichens and mosses. These materials help camouflage the nest. She lines the inside with the softest down and feathers to create a warm, cozy environment for the eggs and chicks.
How Long Does It Take to Build the Nest?
The total time invested in nest building varies based on the hummingbird’s prior experience, weather conditions, and availability of materials. In general, expect the process to take:
- 5-10 days for the female’s first nest of the season
- 4-8 days for the second nest
- 3-6 days for the third nest
Researchers have observed a learning curve, with females building subsequent nests faster than the first. Young birds in their first year take longer constructing a nest compared to mature adults.
Poor weather can prolong the nesting process. The female may pause construction during storms or periods of high winds. Hot temperatures also slow her down. Ideal mild, dry conditions allow for the fastest nest building.
If quality nest materials are scarce, the female has to spend more time foraging across a wider area to find suitable supplies.
When Does Egg Laying Start?
The female Anna’s hummingbird typically lays her eggs in the nest 1-3 days after completing construction. She may rest one full day before starting. Each day of delay lowers incubation time by the same amount. So if she rests 3 days after finishing, the incubation period shortens by 3 days.
The female lays 1-3 tiny white eggs, usually 2. The eggs measure about 0.5 inches long and weigh 0.02 ounces on average. She produces one egg per day in the early morning. Incubation starts after the last egg. The eggs hatch in 14-16 days.
Nesting Facts and Statistics
Here are some key facts about Anna’s hummingbird nests:
- Size: About 2 inches wide and 1.5 inches tall interior
- Weight: Less than 0.1 ounce
- Materials: Spider silk, down, lichens, buds, feathers
- Building time: 3-10 days
- Nest height: 3-20 feet up
- Egg laying: Within 1-3 days after finishing
- Clutch size: Usually 2 eggs
- Incubation: 14-16 days
- Nest cycles per season: Up to 3
Do Males Help Build the Nest?
Male Anna’s hummingbirds play no role in nest construction or incubation of the eggs. Their sole contribution to reproduction is courtship and mating with females. However, the males do help feed the chicks once they hatch. Both parents collect nectar and insects to bring back to the nest.
Research shows disabling the area of the brain tied to courtship behavior causes the males to help build nests. So male hummingbirds have the innate capability for nest construction, though it remains suppressed in normal circumstances.
Other larger hummingbird species do exhibit occasional male participation in gathering nest materials. But the female still takes the lead role in nest building across all hummingbirds.
Fun Facts About Anna’s Hummingbird Nests
- Their nests are about the size of an upside-down thimble.
- The female hummingbird has a wingspan around 4 inches, smaller than the nest.
- She can lay her full body weight in eggs over the breeding season.
- Nests are built so tightly they hold water.
- The nest stretches and expands as the chicks grow.
- A female may reuse and repair the same nest for a second brood.
- Wind, rain, and birds often cause nests to fall before the chicks can fledge.
Interesting Nesting Behaviors
- The female hummingbird lines the nest with feathers, sometimes plucking down feathers from live chickens.
- She sits on the nest even before egg laying, perhaps to shape it further.
- Hummers purposefully decorate the outside of the nest with lichens to improve camouflage.
- They may conspicuously add decoration materials to divert predators from the true nest location.
- The female remains on the nest constantly once incubation starts, even at night.
- She leaves the nest unattended for only a few minutes at dawn and dusk to feed.
Conclusion
Anna’s hummingbird females construct delicate yet durable nests to cradle their eggs and shelter the chicks after hatching. The nest building process requires 5-10 days on average, with the female gathering materials, sculpting the cup shape with her body, and binding everything together with spider silk. She finishes the exterior with lichens and mosses to help camouflage it before starting to lay eggs. While a diminutive structure, the Anna’s hummingbird’s nest represents a huge time and energy investment to ensure reproductive success and survival of the species.
