This series of Entries covers every non-native breeding bird in the UK as part of an online field guide. It will not cover budgerigars, cockatiels or canaries, or some other wildfowl such as bar-headed geese, muscovy ducks or other assorted exotics, as they are not deemed to be sustainable, if breeding in the wild in Britain at all. Non-native is defined as 'relating to, originating from, or having the characteristic of another place or part of the world, and having immigrated, or been introduced, from an area which is outside of its normal distribution range'.

The ruddy duck, Oxyura jamaicensis, is one of two birds of this genus found in Europe and is a member of the family of stiff-tailed ducks. It is one of the many waterfowl found in the UK but is very distinctive due to its blue bill, dark plumage and bulky posture. With its low-slung posture in the water it cannot be confused with any other duck. It is also one of the UK's most colourful ducks. It is a regular in still water, such as ornamental lakes, lagoons and reservoirs, although it is rarely seen in flight.

Taxonomy

Like all living organisms, the ruddy duck is classified according to its physical characteristics. This is known as its taxonomy. All birds share the same basic features:

• Kingdom: Animalia, meaning having life, sensation and voluntary motion.
• Phylum: Chordata, meaning having a notocord, which is the basis of having a spinal cord.
• Sub-Phylum: Vertebrata, meaning having a skeleton and an articulated backbone.
• Class: Aves, or birds, meaning: possessing a horny beak; no adult teeth; large muscular stomach and crop; feathers; yolked, hard-shelled eggs; and a strong, light skeleton.

The ruddy duck is further classified as:

• Order: Anseriformes, the ducks, geese and swans.
• Family: Anatidae, waterfowl in the Anseriformes that possess a penis.
• Genus: Oxyura, the stiff-tailed ducks. The ruddy duck is one of five species in the genus, with two or three others now extinct.

In the Oxyura genus in Europe, there are two ducks; the European native white headed duck, and the American non-native ruddy duck.

Characteristics

This bird measures 35 - 43cm, with a short stumpy flat tail ¹, measuring 6 - 8cm. It is a small, dumpy, short-necked bird, invariably found in water, where it sits very low in the water. The bird has a broad, ridged sky-blue, stubby bill. The male has a black crown with white cheeks and a chestnut body, while the female is more dull and subdued. When it does fly, it is only for short distances and very low. It is not a strong flyer. The tail is either held cockily upright or spread fan-like, level with the water. It dives rapidly and has a strange ability to submerge seemingly without effort.

Its preferred habitat is shallow, still water, rich in floating and submerged plants, fringed with emergent vegetation². It can also be found in sluggish water, but is a weak swimmer. It is omnivorous and strains the mud through its bill for plant seeds and small invertebrates.

The nest is a well-hidden raft, made from a platform of dead reed and rush stems, occasionally interspersed with green foliage, with a shallow indentation. The eggs are a dull creamy white, ovate, with a clutch of 6 - 10 eggs, laid from mid-April to July. Incubation lasts for 25 - 26 days, with fledging at 50 - 55 days. Adults are gregarious with pair-bonding only lasting as long as the fledging period. It rarely calls, but makes occasional 'tic' and 'croak' sounds. These are uttered during courtship by the release of air from the tracheal air sacs, rather than from vocal cords. The sounds can also be a high-pitched 'kwarr' or 'hiss.

English History

The bird is an American native, and the first three pairs were introduced into the UK by Sir Peter Scott at Slimbridge in 1948, to boost his Wetland and Wildfowl Reserve. The first escapees occurred in 1953, facilitated by its exceptional diving ability, making it difficult to catch and pinion³. The first breeding record outside captivity is in 1960. The population had reached 570 breeding pairs by 1991, with an overall population of up to 2,000. This was largely due to the increase in man-made reservoirs and gravel pits, which provide perfect breeding habitats. It was not thought to pose a risk, as its nearest relative is situated at the most southern area of Spain. However it has slowly spread south and is now in direct conflict with the native white-headed duck Oxyura leucocephala which meant that eradication was sanctioned in 2002.

The ruddy duck is slowly being culled throughout parts of Europe, including the UK. There have been a number of reports of interbreeding and, as an introduced bird that would not have naturally integrated with it, most conservation groups have actively supported this idea of culling, which is normally frowned upon. An informal survey in the London Wetland Centre on 12 March, 2007, showed no ruddy ducks present, where previously they had been abundant. Further visits are necessary to confirm culling has been successful.