Tachyeres brachypterus

Falkland_Steamer_DuckThe Falkland Steamer Duck, known locally as the Logger Duck, is a flightless bird found only in the Falkland Islands.These birds can be found with no great effort in the Islands along all low-lying coasts where there is shelter from the full force of the South Atlantic Ocean. In world terms it is a rare bird: it occurs here and nowhere else. Its total population has been estimated (1997) at up to 16,000 pairs of birds.
Description

Falkland_steamer_duck

The male is larger and paler overall. In general, he is grey or white about the head, while the female's head is brown with a white eye-ring and a thin while line curving from the eye down the side of the head. Young males and some adult males in moult may also have a white line behind the eye, but this is less clear-cut.Differences in colouration between male and female are not unusual in the duck family. Only females incubate the eggs. The male’s more 'showy' appearance serves to attract the female, and makes him more obvious to other birds when defending his territory.
The male is large – one of the biggest ducks in the world. An adult drake may weigh around 3½ kg and measure 80cms from the tip of his bill to the end of his tail. Both sexes, when adult, have orange-yellow legs and feet. Those of immature birds, of either sex, are paler and have black marks at the heel and toe joints. All individuals have spurs, bare of feathers, at the angle of the wing. An adult male defending territory will have well-developed, bright orange spurs, which he will use to good effect in violent combat with other males.It is a noisy bird. The alarm call of the male can be heard far away – a wheezy 'cheeeroo'. The most distinctive sound made by the female is a deep bass croaking note, delivered with beak pointing to the sky. Both sexes have a variety of quiet contact calls.

(Photo above - Male and female steamer ducks are distinctively different in appearance. The bill of an adult male is bright orange, with a prominent black tip. The female bill is greenish-yellow)

 

Behaviour

Steamer_ducks_preeningSteamer ducks preening.

The Falkland Steamer Duck is flightless, but it can race speedily over the water, propelling itself with both wings and feet. It does this in a large cloud of spray, as its breast ploughs the water like the prow of a ship. Its wings are perfectly formed but when folded are shorter than its body.They are very aggressive, and can only be kept successfully in captivity singly or as mated pairs, isolated from other birds. A zoo specimen was once reported to have killed a swan several times its own size.

Falkland_steamer_duckThese ducks will 'steam' when trying to escape danger, or when battling with each other.
(Photo: Alan Henry)

In the wild, mated pairs hold and defend a territory – a waterfront and adjoining sea area – against all comers. Favoured locations are ones with sheltered inshore waters and a plentiful supply of food. In such areas there may be territories every 300 metres or so. Whenever a territorial male catches sight of its neighbours, or if wandering unmated birds encroach on his territory, a face-off occurs. This occasionally takes the form of a fierce and bloody battle, in which the female of the pair also takes part. Sometimes, one of the combatants is killed or dies of wounds. This bloodletting is exceptional in the bird world. With other territorial species, such arguments usually lead to a lot of puffing and posturing, but no actual combat.Immature birds and unmated adults often band together in groups, sometimes numbering more than three hundred. Individuals within flocks normally tolerate the presence of others in the group although as spring approaches there is always some skirmishing. Inevitably, flocks are forced to keep away from occupied territories, but must still remain in areas where there is plenty of food. So, flocks are often found in large sheltered bays where there are shellfish beds seaward of the defended territories. In the spring, individuals and small groups will encroach on the established territories, and much fighting takes place.

 

Food

Steamer ducks feed on a variety of small marine animals living on the seabed. They will upend to feed in very shallow water, but mainly they dive to secure their prey. They use both wings and feet to propel themselves underwater. When one bird from a large flock dives, often most of the others go down at the same time. They will emerge almost simultaneously 20-40 seconds later, bouncing to the surface like a lot of corks. No detailed studies of the ducks' diet have been undertaken, but we know that mussels are a favourite item and that they also eat other bivalves, sea-snails, limpets, shrimps and crabs.

 

Predators

Even though a bold and aggressive bird, the Steamer Duck always gives way when it meets a sea lion. Sea lions are today the only significant predators of the adult birds. From time to time they catch and kill an unwary bird. Formerly, they would have also been preyed on by the warrah, or Falkland fox. This was the only land predator before man came on the scene. The warrah is no longer with us; it was persecuted by the early settlers in the Falklands because it killed sheep, and the last one was shot in 1876. Even today, Steamer Ducks will head quickly for open water if a dog appears over the horizon, but will allow humans to approach more closely. On land, they can run remarkably fast for ducks. This is probably an adaptation which once helped them to escape sudden attacks by foxes.

 

Other Threats

The Steamer Duck is very vulnerable to coastal pollution. Like all waterfowl, it is at risk from oil pollution, which clogs the feathers and destroys their waterproofing. Sediments deposited from sewage outfalls, or peat run-off from the land, can smother shellfish beds on which they feed.

 

Courtship and Nesting

Flying_steamer_duck

Young Steamer Ducks.

It hides its nest in long grass or diddle-dee; occasionally in dry kelp tangles, old penguin burrows or jumbled boulders. The nest itself is a slight hollow in the ground lined with grass and soft down feathers. It is usually within easy sprinting distance of the seashore, but nests have been found up to 400 metres from the sea. Typically, the bird lays 5 - 8 eggs, rarely more. Nests with eggs have been found in most months of the year, but mainly in the period September - December. The female alone does all the incubation, as is usual with duck species. She will leave the nest to bathe and preen for 15 - 30 minutes each day, covering her eggs with nest materials before she goes. It is not known if she feeds at all when on eggs. The incubation period is thought to be 26 - 30 days from when the last egg is laid. While the female remains hidden on the nest, the male patrols the territory and chases away all-comers.

 

Flying Steamer Duck

Flying Steamer Duck.
(Photo: Alan Henry)

Another species of steamer duck is found in the Falklands – the Flying Steamer Duck Tachyeres patachonicus (known locally as the canvasback). This bird, however, is not unique to the Falklands as it also occurs over a large part of southern Argentina and Chile, often far inland. It is a slimmer, flying version of the Falkland Steamer Duck. Nowhere in the Falklands is it as common as its cousin. It usually nests near inland freshwater ponds and feeds both in freshwater and the sea. In winter it is found mainly in sheltered sea inlets and bays.

Adapted from The Logger, Falkland Islands Foundation, 1986.