The Common Goldeneye (Bucephala clangula) is a medium-sized sea duck of the genus Bucephala, the goldeneyes. The birds breed across northern Europe, Asia and North America in boreal forest areas with lakes or ponds. Their nest is a key part of their breeding ecology and behavior.
What kind of nest does the Common Goldeneye build?
The Common Goldeneye builds its nest in tree cavities or old nest boxes made for breeding ducks. The female chooses a nesting site in a cavity with a small entrance hole, usually in a large tree near water. Cavities in live trees, stumps, logs, or snags are used. The cavity needs to be deep enough so the eggs and incubating female are protected from predators and weather.
The nest itself is made of materials like down, lichen, moss, grass and leaves which are laid on top of the rotten wood debris already present in the cavity. The nest cup is typically 6-18 inches wide and 1-3 inches deep. It is built by the female in late April or early May before egg laying starts.
What tree species are used?
Tree cavity species preferred by Common Goldeneyes include aspens, maples, willows, oaks, poplars, beech, birch and alders. Conifers like pines or firs are rarely used. The female chooses cavities in larger diameter trees, with entrance holes about 3-4 inches wide.
Why does the nest need to be in a cavity?
Nesting in a tree cavity provides several key benefits:
- Cavities offer insulation and shelter from weather and predators
- The small entrance hole keeps the eggs and incubating female protected
- Cavities have stable temperature and humidity for incubating eggs
- The nest is concealed and secluded from distubances
- Tree cavities provide a more secure nest site than ground or open shrub nests
For these reasons, the enclosed cavity nest is important for successful breeding of the Common Goldeneye. The female chooses the cavity site carefully based on criteria like cavity depth, entrance width and tree size and species.
What is the typical clutch size?
The typical clutch size for Common Goldeneye nests is 6-15 eggs, with an average of about 9-10 eggs. The eggs are pale greenish-blue and oval shaped, with smooth, glossy shells. They measure approximately 2 inches long by 1.5 inches wide.
The female begins laying eggs in late April or early May, at a rate of 1 per day. She does not start incubating until the clutch is complete, which takes about 10 days. This synchronized hatching helps the young survive. The female diligently incubates the eggs for the 28-30 day incubation period.
How many broods per year?
The Common Goldeneye usually raises only one brood per breeding season. Occasionally a second brood may occur, but this is rare. Their cavity nest sites are limited, so multiple broods are unlikely.
After hatching and rearing the young, the female will spend the rest of the summer molting and fattening up for winter. The male leaves the female about 2 weeks into incubation, and departs the breeding grounds in early summer after mating season.
Where are goldeneye nests located?
Common Goldeneyes nest near ponds, lakes, rivers or wooded wetlands across the northern boreal forests in Europe, Asia and North America. They require cavities near water where they can forage.
Some key nesting location facts:
- Found in higher densities in boreal forest areas with suitable wetlands
- Cavities are in large trees within 330 feet of water, usually much closer
- Often nest in groups if suitable habitats exist, with multiple pairs near each other
- Prefer wetlands with islands for nesting cover from predators
- Nest sites are traditional and may be reused for decades by successive pairs
Their nesting habitats are associated with mature forests, since old or dead trees provide nest cavities. Loss of nesting sites due to logging limits goldeneye breeding in some areas. Proper forest management is needed to maintain nesting cavities.
What is the nesting density?
Nest density varies across the range, but averages about 6-10 nests per square kilometer in prime habitat. In exceptional areas, densities up to 60 nests per square kilometer have been recorded.
Nest boxes have also been provided in some areas to increase nesting sites. However, natural tree cavities are preferred and have higher occupancy rates. Conserving mature forest wetland habitats with natural cavities is key for sustaining goldeneye populations.
Do males participate in parental care?
No, male Common Goldeneyes provide no parental care and leave females to incubate eggs and raise the young alone. Their mating strategy is often called “mate desertion.”
Key facts about male involvement:
- Males abandon females about 2 weeks into the incubation period
- They depart the breeding areas for molting sites further north
- The female incubates the eggs and rears ducklings by herself
- Males play no role in nest defense or protecting the brood
- Single mothers attend to all parental duties for their offspring
This lack of male parental care is common in waterfowl species. It allows males to molt earlier and compete for new mates each breeding season. Meanwhile, the female is left to raise the brood alone.
Conclusion
In summary, the Common Goldeneye nest is an important part of its breeding ecology and life history. Key facts include:
- The nest is built by the female in a tree cavity near water
- Cavities provide insulation, shelter and concealment
- Clutch size averages around 9-10 eggs
- Only one brood is raised per year, with no male parental care
- Cavities are often in aspens, willows and other boreal trees
- Nest sites are reused for many years if undisturbed
Conserving mature forests with natural cavities and wetlands is crucial for sustaining Common Goldeneye populations. Proper habitat and cavity availability allows this species to successfully breed across the northern regions of Europe, Asia and North America.
Location | Estimated Population |
---|---|
Europe | 310,000-340,000 pairs |
Asia | 100,000-1 million pairs |
North America | 200,000-250,000 pairs |