The Great Crested Flycatcher is a medium-sized bird that breeds in eastern North America and winters in southern Florida, Mexico, and Central America. This flycatcher gets its name from the prominent crest of feathers on its head and its insectivorous diet. Great Crested Flycatchers are cavity nesters, building their nests in the holes of trees or manmade structures. Their nests are intricate structures made up of a variety of materials. In this article, we will take an in-depth look at the components and construction of a Great Crested Flycatcher’s nest. Understanding the specifics of nest building in birds provides insights into their behavior, ecology, and evolution.
Where Do Great Crested Flycatchers Build Their Nests?
Great Crested Flycatchers nest in the cavities of trees, often old woodpecker holes. They prefer deciduous trees such as maples, elms, oaks, poplars, and cottonwoods. The entrance to the nest cavity is usually quite high off the ground, at an average height of around 15-20 feet. The cavity provides shelter and some protection from predators. Great Crested Flycatchers will also readily use nest boxes put up by humans and may even nest behind shutters or vents on houses or other structures. The cavity or nest box should be about 4-12 inches deep and have an entrance hole diameter of around 2-3 inches for the flycatchers to be able to fit through. Whatever site they choose, Great Crested Flycatchers typically return to the same nesting area year after year, often even reusing the exact same cavity.
When Does Nest Building Occur?
Great Crested Flycatchers time their breeding to coincide with the spring burst of insects that will nourish their young. They arrive on their breeding grounds anywhere from mid-March to May depending on the latitude. Courtship and pairing takes place shortly after arrival. Nest building usually begins around mid-April but ranges from late March in the southern part of their range to June in the northernmost areas. The female undertakes most of the nest construction work, though the male may bring some material. The nest is built in the few weeks leading up to egg laying, which generally commences in May or June. Timing varies locally depending on spring temperatures and food availability. Great Crested Flycatchers are single brooded, having just one clutch per year even if the first nest fails. However, they may produce a second brood if conditions allow early enough in the season.
What Materials Do Great Crested Flycatchers Use?
The foundation of the Great Crested Flycatcher’s nest consists of a coarse base layered with finer, softer materials on top. Typically the base is made of twigs, rootlets, pine needles, pieces of bark, stems, leaves, and other coarse elements. The interior cup where the eggs will lie is lined with softer substances like grass, moss, algae, feathers, animal hair, flowers, lint, paper, or other fine fibrous materials. Great Crested Flycatchers are opportunistic in using what nest materials are available in their habitat. Different pairs may use slightly different materials depending on the local plant life. Their adaptations allow them to construct well-insulated and sturdy nests in a variety of environments across their range. Occasionally more unusual objects like shed snakeskin or bits of plastic may be woven in as well. The flycatchers often decorate the exterior rim of the nest with shed snake skins, paper, aluminum foil, cellophane from cigarette packs, or other debris. Scientists are unsure if this ornamentation serves any functional purpose or is just decorative.
How is the Nest Constructed?
Nest building is an intricate process that is thought to be innate rather than learned behavior in birds. The female Great Crested Flycatcher uses her beak to weave and intertwine the materials together into a sturdy basket-like structure. She often gathers the materials from the ground but may also break materials directly off of trees and other vegetation. The base of the nest consists of coarse twigs, evergreen needles, and pieces of bark laid in a circular or cup shape. The female flycatcher manipulates and adjusts the materials, working them down into the cavity with her body. She continues to add material, circling the nest while turning and carefully weaving the fibers together with her bill. This measured weaving behavior results in a tightly knitted base that conforms to the cavity space.
Once the coarse outer shell is crafted, the female then lines the interior with softer grasses, algae, moss, feathers, fur, and other insulating substances. This interior cup provides a tightly woven, smooth surface to cradle the eggs and insulation to help maintain incubation temperatures. The rim of the nest is often fringed with ornamental bits of trash, skins, or other odds and ends from the environment. The males may occasionally bring material to the female but does not participate substantially in weaving the nest. Nest construction is an impressive feat of bird engineering and craftsmanship. The intricate nests are well-suited to the needs of the Great Crested Flycatchers.
What Are the Dimensions of the Completed Nest?
The nest’s dimensions are constrained by the size of the cavity or nest box chosen by the Great Crested Flycatchers. But within those parameters, completed nests tend to be around 6 inches tall with an interior cup about 5 inches wide and 3 inches deep. The nest walls are an inch or two thick as a result of the weaving construction process. Nests are often slightly smaller in natural cavities compared to nest boxes. The entrance hole is usually about 2-3 inches wide, allowing the adult flycatchers to pass in and out. Overall nest sizes can vary based on the materials available and the diligence and skill with which the female weaves the nest. Placement of the nest within the cavity also varies, with some nests placed higher and others lower down in the space. But all completed nests share the attributes of a sturdy basket-like structure and soft interior lining suited to hold the flycatcher’s eggs and young.
Conclusion
Great Crested Flycatcher nests are impressive feats of animal engineering. The female flycatcher uses available plant and other materials to weave a tightly knit basket structure. An insulating soft lining completes the inner nest cup. Nest locations high in tree cavities provide security while their intricate construction provides durability and a comfortable place for eggs and nestlings. Nest building is driven by innate behaviors but is also shaped by available resources and the individual skill of each female flycatcher. The nest’s form elegantly fulfills its function in safely housing the next generation of Great Crested Flycatchers. Observing the nuances of nest building gives us insight into the natural histories of birds and how nest structures evolve as adaptations to their environments and breeding needs.
The size, shape, placement, and composition of the nest all contribute to its functionality:
Nest Attribute | Function |
---|---|
Placement in high tree cavity, 15-20 ft up | Protects from predators |
Cavity is 4-12 in deep and 2-3 in wide | Sized for the birds to fit and build nest |
Coarse base of twigs, bark, etc. | Provides sturdy structural foundation |
Lined interior cup 3 in deep and 5 in wide | Holds and insulates the eggs |
Soft lining of grass, moss, feathers | Insulates and cushions eggs and nestlings |
Key stages in the nest building process:
Stage | Activity | Function |
---|---|---|
Site selection | Choosing cavity in dead tree or nest box, often reusing the same site across years | Provides secure nesting spot familiar to the birds |
Gathering materials | Collecting twigs, grasses, moss, feathers from the ground or breaking them directly off vegetation | Gathers appropriate resources for nest construction |
Weaving base | Intertwining coarse materials like twigs into a sturdy basket shape with her bill | Creates a durable, rigid foundation to hold nest’s shape |
Lining cup | Adding softer grasses, feathers, etc. to create a smooth, insulated interior | Forms a comfortable, warm, protected bed for the eggs and nestlings |
Ornamenting | Decorating nest exterior with snake skins, bits of paper, foil, etc. | Unknown function – possibly deter predators or decorate for mate attraction |
Differences between male and female roles:
Sex | Nest Building Roles |
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Female |
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Male |
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In summary, the Great Crested Flycatcher builds an intricate, woven nest lined with soft materials inside a tree cavity or nest box. The female flycatcher takes the lead in nest construction, gathering materials and expertly weaving them into a sturdy basket-like structure with her bill. She then lines this with finer materials to create a cup-shaped interior for the eggs. The nest provides a safe, protected space for breeding high off the ground. Construction of the nest is driven by innate behaviors shaped by evolution to create effective nests from available materials. Observing the nest building behaviors and nest structures of birds provides insight into their natural history. The Great Crested Flycatcher’s elegant nest is a testament to the building capabilities of birds.