The female Rufous Hummingbird (Selasphorus rufus) constructs a tiny cup-shaped nest to lay and incubate her eggs and raise her young. The nest is an intricate structure made primarily of plant down and spider silk, allowing it to expand as the chicks grow. It is built in the branches of trees and shrubs, securely fastened so it can withstand wind and rain. The nest building process takes 6-9 days to complete and the female uses a variety of techniques to construct it. She collects materials from the environment and weaves them together using her feet and beak. The final nest is only about 2 inches wide and half an inch deep but is remarkably strong and durable. Understanding the details of the Rufous Hummingbird’s nest provides insights into her reproductive behavior and adaptations for breeding success.
Where Does the Female Build Her Nest?
The female Rufous Hummingbird is selective about the location for her nest. She typically chooses an open, exposed branch away from the tree trunk. Ideal nest sites provide a supporting foundation for the structure and visibility for the bird to spot potential threats. Favorite locations include horizontal branches in deciduous trees, coniferous trees, shrubs, poles, and culverts. The height ranges from 3 feet to 50 feet off the ground. Lower heights are preferred in shady forest areas whereas higher places are favored in open meadows. The female bird assesses the building materials in the vicinity when selecting a nesting site. An abundance of downy plant fibers, spider silk, lichen, and moss materials in the area ensures she can construct a quality nest.
Ideal Nest Locations:
- Horizontal branches of trees and shrubs
- Higher sites in open meadows
- Lower sites in shady forest areas
- Supporting foundation for the structure
- Visibility for spotting threats
When Does Nest Building Occur?
Nest building occurs in early spring which coincides with the Rufous Hummingbird’s migration pattern. The male arrives at the breeding grounds along the Pacific Northwest coast between March and early April. The female follows a couple weeks later in mid to late April. Upon arrival, the female starts scouting for nest locations and suitable materials nearby. Nest construction takes place in April through May. The timing depends on the latitude and elevation which impacts weather conditions. More northern and higher altitude areas see later nesting. The female works diligently as the nest must be completed in 6-9 days prior to egg laying. She may build a second nest for raising a subsequent brood later in summer. The cycle continues with 1-2 broods per season until fall migration in July and August.
Nest Building Timeline:
- Early spring in April and May
- After female arrival at breeding grounds
- Before egg laying in late April/early May
- 6-9 days construction time
- 1-2 broods per season
What Materials Does the Female Use?
The female Rufous Hummingbird uses a variety of plant and spider silk fibers to build her nest. Her preferred materials include:
Plant Down:
- Cottonwood
- Willow
- Cattail
- Thistle
- Fireweed
This provides the soft, insulating base of the nest. The female collects downy tufts and weaves them in a circular pattern using her beak and feet to compress the fibers.
Plant Fibers:
- Grasses
- Twigs
- Bark
- Lichen
These give structural support to the nest and are layered around the exterior. The bird gathers stripy fibers and attaches them to the base.
Spider Silk:
The female locates spider egg sacks and gathers strands of silk. This is a key binding material used to adhere the plant down and fibers together. The stretchy silk allows the nest to expand as the chicks grow.
Camouflage:
- Moss
- Lichen
- Bark
The female weaves in bits of moss, lichen, and bark to add camouflage and strengthen the nest walls. This helps the small nest blend in with the surroundings.
Other:
- Feathers
- Buds
- Seeds
The female may incorporate feathers, buds, seeds, or other handy materials. But plant down and silk make up the primary portion.
What is Her Nest Building Technique?
The female Rufous Hummingbird uses a meticulous process to construct her nest over 6-9 days:
Day 1:
- Selects nest site
- Collects initial downy materials
- Builds base layer of nest
She chooses a proper branch and starts gathering downy tufts to form a soft inner core.
Days 2-4:
- Adds structural fibers
- Locates spider silk
- Incorporates binding materials
The female weaves sturdy fibers around the nest and binds them with sticky spider silk.
Days 5-7:
- Camouflages exterior
- Shapes cup of nest
- Secures to branch
She conceals the nest with bark and lichen, shapes the inner cup, and ensures it is firmly attached.
Days 8-9:
- Applies finishing touches
- Allows materials to dry and set
- Secures nest to withstand elements
The female adds final touches, lets the structure dry, and reinforces the stability. Her nest building is complete.
What Does the Completed Nest Look Like?
The finished female Rufous Hummingbird’s nest is only 2 inches wide and a 1/2 inch deep but is a masterpiece of avian architecture.
Key Features:
- Small, compact cup shape
- Cup interior lined with soft plant down
- Cup exterior wrapped with fibers for structure
- Exterior camouflaged with lichen and bark
- Bound and reinforced with stretchy spider silk
- Attached securely to a branch
Despite its tiny size, the nest is durable enough to withstand rain, wind, and the growing chicks inside. The stretchy spider silk and inner down allow the structure to expand. The camouflage blends the nest into the surroundings to protect from predators. The diligent efforts of the female Rufous Hummingbird ensure her eggs and chicks are housed in a protective shelter.
Nest Statistics:
- 2 inches wide
- 1/2 inch deep
- 1-1.5 grams weight
How Does the Nest Expand for the Chicks?
The female Rufous Hummingbird’s nest is built with specialized materials to accommodate her growing chicks. As the 2 tiny eggs hatch and the chicks mature over 2-3 weeks, the nest is designed to flex and stretch.
Key Flexible Materials:
- Spider Silk – The silk strands woven throughout the nest walls provide elasticity to handle outward pressure and prevent the structure from collapsing.
- Plant Down – The interior downy lining allows for some compacting as the chicks grow. The soft fibers prevent them from poking through the walls.
Nest Expansion Process:
- Nest holds 2 small eggs in shallow cup
- Chicks hatch and gain mass over 2-3 weeks
- Spider silk stretches and down compresses
- Nest walls bulge out slightly to accommodate chicks
- After chicks fledge, nest returns to original size
The brilliant nest architecture of the Rufous Hummingbird female provides both strength and flexibility to protect her vulnerable chicks until they are ready to leave the nest.
How Does the Nest Camouflage Help Protect the Eggs/Chicks?
The Rufous Hummingbird nest relies on camouflage for protection against predators in the exposed locations the female selects.
Camouflage Strategies:
- Colors – She weaves in bark, lichen, and moss that match the tree colors
- Positioning – Locates nest on underside of branches away from trunks
- Small Size – The tiny 2-inch nest is hard to spot
- Materials – Fibers blend into the tree bark
Benefits:
- Prevents detection from visual predators like birds and squirrels
- Conceals during both incubation and nesting periods
- Allows the female to forage away from nest
- Doesn’t require active nest defense
The camouflage adaptations of the hummingbird nest are essential given the threats posed by tree-climbing mammals, snakes, jays, crows, and other birds. By relying on stealth rather than active defense, the hummingbird can minimize time spent at the nest and maximize time finding food.
Conclusion
The tiny nest created by the female Rufous Hummingbird is a marvel of specialized bird architecture. Its cupped shape, flexible materials, camouflage exterior, and secure construction all support the survival of the eggs and chicks. The nest’s impressive durability and expandability highlight the hummingbird’s amazing adaptations for breeding success. Understanding the details of her nest building provides insight into the hummingbird’s reproductive behaviors and strategies. The dedicated female hummingbird engineers a strong and expandable nest that allows her vulnerable young to thrive.
