The duck of the tree hole

A boreal nester turned winter visitor

The common goldeneye is a compact, handsome diving duck of Anatidae. It is one of the few ducks of the northern forests that nests not on the ground but in tree holes. The same bird rears its young in the old chamber of a black woodpecker beside a Siberian lake. In winter it sits on the ice-free lochs and reservoirs of Britain and the Low Countries. The male’s glossy green-black head and round white cheek spot make it a sought-after winter duck. The bird belongs to the boreal zone, not the marsh.

It is built for diving. It has a large head and a short bill. Its body slips under the water with one forward leap. It feeds alone or in small parties on open water. It springs clear of the surface when alarmed. It bursts into a fast, whistling flight.

The showy drake and the plain brown female show the clearest sex difference among ducks. The goldeneye is a creature of the cold north. In western Europe its winter numbers have risen a little. Nest boxes let it breed well south of its natural range. It is now a regular, welcome sight on the reservoirs and gravel pits of the shore. Its true home stays the forest lake of the taiga.

Family tree

Bucephala, the northern divers

The common goldeneye is in the genus Bucephala, a small group of northern diving ducks. They differ from the larger Aythya divers by the larger head and the shorter bill. They nest in tree cavities. The goldeneye is close to the Tufted Duck (Aythya fuligula). That open-water diver shares the dark back, the white flank and the gregarious winter habits.

This shows that the diving ducks are a northern spread of short-billed birds. They took to the ponds and lakes of the holarctic in several lines. Linnaeus described the bird in 1758. Experts now see two subspecies. The birds of the east are larger on average than those of the west.

Nest boxes have let the temperate birds spread south of their natural range. The boreal birds have held their numbers. The centre of the species stays the taiga. Its winter flocks of the west have grown.

Green-black head, white spot

How to identify one

An adult common goldeneye is 40 to 50 centimetres long. Its wingspan is 70 to 84 centimetres. The female weighs about 0.5 kilogram. The larger male can reach 1.4 kilograms. The set-back legs give it a neat, round shape on the water. Its take-off is clumsy. It needs a long run across the surface before it lifts. The male in breeding dress has a large glossy head of green-black.

A round white spot sits below the eye. His back is black. His flank is white. His rump is black. His eye is a vivid golden yellow, which gives the bird its name. The female is plain grey-brown with a brown head. She has a white collar at the neck base and a duller yellow eye. The two are told apart by the head colour and the male’s white cheek spot.

The wings are short and pointed. Flight is fast and direct. The air whistles through the feathers, which gives the bird its Swedish name. The voice is mostly silent outside the breeding season. The female gives a harsh croak and the male a thin pipe in spring courtship. The wing feathers moult soon after breeding. The flightless adults gather on safe water for three or four weeks.

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Forest lakes and winter bays

Where it lives

The goldeneye lives in the boreal forest and the cold, clear lakes within it. For breeding it needs the still water of the forest zone and the old tree cavities beside that water. For winter it needs the ice-free lochs, reservoirs, gravel pits and sheltered coastal bays of the temperate shore. The species is absent from the open sea and the warm lowland marsh. It is a creature of the still, wooded margins of the north.

In summer the birds nest across the forest and forest-tundra of the holarctic. They range from Scotland and Scandinavia east through Russia to the Pacific. They need lakes with a fringe of pine and dead trunks for holes. In winter most of the western birds gather on the large lakes of Britain, Ireland and the Low Countries. They also line the sheltered coasts of the Baltic and Atlantic.

They may join the related tufted duck. The goldeneye is a strong, regular migrant. It moves south only while the water stays open. Rings show a single bird returns to the same winter lake for several years.

A carnivorous diver

What it eats

The goldeneye is a carnivorous diver. Its diet is aquatic insects, crustaceans and small molluscs. A bird takes these from the lake bed and margins. It stays under for twenty to forty seconds at a stretch. It feeds at depths of up to ten metres.

A bird on a clear lake dives without rest. It moves across the bottom in search of prey no surface feeder could reach. To this animal diet it adds small fish and fish eggs where they are many. In the breeding season it takes the invertebrates that supply protein for the eggs. The goldeneye dives, rather than filters, to feed.

It swallows grit to help the gizzard crush hard shells. It tolerates cold and dirty water well. This is why it thrives on the reservoirs and gravel pits of the lowlands. It is among the ducks most at risk from lead shot on the beds of shooting waters. The ban on lead in wetlands has cut but not ended this poison.

A hole for a nest

The breeding cycle

Goldeneyes pair in late winter and early spring. The bond lasts one breeding season, not life. The drake leaves the female as she starts to sit. He takes no part in the young. The female alone picks the nest cavity, lines it and tends the brood. Nesting starts in late April and runs into June. The site is a hole in a tree.

Most often it is the old chamber of a black woodpecker or the rot hole of a broken trunk. The bird will also take a nest box by a forest lake. The female lays a clutch of six to thirteen eggs on bare wood or on down from her breast. She sits on them alone for twenty-eight to thirty-two days. She leaves the cavity only to feed and bathe. By then the drake has left for the moult flock. The ducklings can walk soon after hatch.

They hatch in a tree, so they must leap to the ground and then to the water within a day or two. Their mother leads them to the shallows. She broods and defends them against shore predators. They can fly at fifty to sixty days. By then the family has split up and the young have joined the flocks that take them south.

A northern success

Conservation

The common goldeneye is Least Concern on the global Red List. Its recent history is mostly a win. The boreal populations of the east have held their numbers. The western populations have grown. Nest boxes and the protection of forest lakes helped this. The species is now a regular breeder well south of its natural range. It is a common sight on the winter wetlands of Britain and the Low Countries.

The species is protected across its range. In Scotland and Scandinavia the key breeding lakes have nest boxes. They are managed to hold the dead wood the bird needs. The international deals on migratory waterbirds have cut the shooting on passage and winter flocks. Yet the bird depends on the old trees of the boreal forest. It is vulnerable to the clear-fell that removes the cavities. It is listed on the African-Eurasian Waterbird Agreement as a bird of interest.

The main threats are the loss of the dead wood the nest needs. The lead left in wetlands still hurts. Recreation disturbs the best waters. The change in the forest turns old pine into clear-fell. Managing the goldeneye means keeping the dead trunks and the nest boxes across the forest zone and controlling the mammals that take the eggs.

Quick hits

Five things to remember

• The goldeneye is one of the few ducks that nests in a tree hole, not on the ground. It most often uses the old chamber of a black woodpecker. It will also take a nest box by a forest lake.
• The ducklings hatch high above the ground. They must leap from the nest to the forest floor and then to the water within a day or two of hatch. They survive the drop because they are so light and so well insulated.
• The male has a glossy green-black head with a round white cheek spot and a golden yellow eye. The female is plain brown with a white collar. The two sexes look like different birds on the water.
• The flight of the goldeneye makes a loud whistle of air through the wings. This gives the bird its Swedish name. It carries well across the winter lake.
• The goldeneye was once badly hit by lead shot on the beds of shooting waters because it swallowed the pellets with its food. The ban on lead in wetlands has cut but not removed the risk.