Bristol Waterfowl 1: Chiloe Wigeon

A.sibilatrix

When Bristol Zoo was opened 175 years ago the centrepiece was a large lake on which a variety of waterfowl were kept. Although the species have changed over the years we still have waterfowl on the lake as display birds and also more important species in various aviaries where they can be better protected from the ever-present urban fox and also receive special care. This series of posts will be about the various ducks (and one goose) held at Bristol.

A.penelope

Often these days preferring the moat around the Gorilla Island is a small group of Chiloe Wigeon, Anas sibilatrix. These belong to a small clade within the huge genus of dabbling ducks, whose most famous member is the Mallard. Other members of the clade are the European Wigeon, A.penelope and the American Wigeon, A.americana. More distantly related are the Falcated Duck A.falcata and the Gadwall, A.strepera.

A.strepera

The true wigeons are distinguished by a short bill, which they mainly use on land to graze on grasses and sedges. Just north of Bristol at the Wildfowl and Wetlands Trust site at Slimbridge thousands of European Wigeon arrive from further north to spend the winter, and are constantly marching across the fields feeding up for the spring return migration and nesting season. Other dietary items are seeds, other plant parts, and (especially as ducklings) insects and crustaceans.

In the wild, Chiloe Wigeon have a vast range in the southern part of South America, where they frequent marshes, pools, and slow-moving rivers in the breeding season. As a result of their large distribution, they are currently classed as of least Concern by the IUCN

After breeding, they disperse to the coast and migrate north as far as Brazil for the southern winter. As with most ducks, they can travel far and fast at times, and have reached South Georgia and other sub-Antarctic islands, and also breed on the Falkland Islands.

Breeding in Chiloe wigeons is similar to most ducks. The nest is a scrape concealed in waterside vegetation, and 6-10 eggs are the usual clutch. Although the male does not incubate, he guards the nest area (and probably the female) against predators and rival males. The ducklings fledge at around 6 -8 weeks, but will probably not breed until they are at least one year old and more usually two. In captivity at least they can live to be 20 years old.


A.americana



The first Chiloe wigeons to be seen in Europe alive arrived in 1873, and they soon proved easy to breed and care for. For this reason they are popular beginner’s birds with private keepers, as they will live and breed happily in even fairly modest sized water bodies. With waterfowl, as with poultry, a key issue is protecting birds from predators, especially when they are nesting. It is vital that back garden birds are surrounded with a fox-proof fence (raccoon-proof as well in the US). Obviously they also need a pond, but the depth of this for dabbling ducks does not need to be very great. More important is that the pond be able to be emptied, cleaned, and refilled easily, as ducks produce a lot of waste and are mostly large birds – Chiloe Wigeon can weigh 2 kg as an adult.



A.falcata



For more on waterfowl, see the British Waterfowl Association website at http://www.bwa.org.uk/

For a video of live Chiloe Wigeons, see here: http://www.youtube.com/watch?v=xKLO8jX7134

(image from wikipedia)

Nest week, the other ornamental we have – the American Wood Duck