Rosy-billed pochard

The rosy-billed pochard (Netta peposaca), alternatively named rosybill or rosybill pochard, is a member of family Anatidae. Though classified as a diving duck, this pochard feeds more like a dabbling duck feeding on seeds roots, sedges, aquatic plants and other grasses.<ref name=":3">Template:Cite web</ref><ref name=":6">Template:Cite journal</ref> Netta is Ancient Greek for "duck" and peposaca is a transcription of the Guaraní name of this species which means "showy wings", referring to the broad white stripe that is only visible with stretched out wings. Male characteristic features include a bright red bill with a rounded knob at the base.

The rosy-billed pochard is endemic to South America. It is found in Argentina, central Chile, Paraguay, Uruguay and southern Brazil. The population in southern Argentina migrates northward during the austral winter, reaching Brazil and southern Bolivia. It is a vagrant to the Falkland Islands.<ref>Wildlife Information: Netta peposaca Template:Webarchive</ref>

Taxonomy

The rosy-billed pochard is one of five pochard species that make up the genus Netta, which is one of 31 genera of the subfamily Anatinae.<ref>Template:Cite web</ref> Within subfamily Anatinae, there is a tribe called Aythini.<ref name=":0">Template:Cite journal</ref> This tribe was thought to be limited to the Northern Hemisphere (what was believed to be the Palearctic), and experienced three or four bursts of speciation, one of which was by the ancestor of the rosy-billed and southern pochards.<ref name=":0" /> Rosy-billed pochards were first described in 1816 by taxon author Viellot, in Paraguay and Buenos Aires, Argentina.<ref name=":1">Template:Cite journal</ref> The species is highly autapomorphic and is placed in a sister-group with the southern pochard, but evidence for this relationship is lacking.<ref name=":0" /> Additionally, they have been known to hybridize with the red-crested pochard and other pochards from ornamental waterfowl collections.<ref name=":1" /> The rosybill is monotypic and thus no further classifications exist.<ref name=":1" />

Description

Like many other members of family Anatidae, the rosy-billed pochard exhibits significant sexual dimorphism.<ref name=":5">Template:Cite journal</ref> Males have a purplish-black head, neck and breast with gray sides, a white area on the crissum (the area around the cloaca), and a bright red bill and red eyes.<ref name=":2">Template:Cite journal</ref><ref name=":3" /> The bill has a large rounded knob, which is bright red, and rest of the bill gradually fades towards a pale pink before ending with a black tip.<ref name=":2" /> The rounded knob of the bill increases in size and intensity in colour during the mating season.<ref name=":3" /> When in flight, the mostly dark plumage noticeably contrasts with the white primaries and secondaries.<ref name=":2" /><ref name=":3" /> The legs and feet are yellow to orange.<ref name=":3" /> On the other hand, females are dull and brown.<ref name=":2" /> The bill is bluish-gray with a black tip and the legs are yellow-orange to gray.<ref name=":2" /><ref name=":3" /> The contrasting white crissum is the most noticeable feature on females.<ref name=":2" />

Young are almost identical in appearance to the females, but their underparts are darker.<ref name=":3" /> Rosybill adults lack the dull eclipse plumage that is characteristic of northern individuals of the genera Aytha and Anas.<ref name=":5" />

Males tend to be slightly larger than females, but in general both sexes are very similar in terms of body size.<ref name=":6" /> Adults can grow to about 22 inches (56 cm) in length and weigh 2.2-2.6 pounds (1-1.2 kg).<ref name=":4">Template:Cite web</ref> Despite these pochards being strong fliers, their blunt-tipped wings require a faster wing-beats than that of many ducks and they have some trouble taking off.<ref name=":4" /> They do not walk as well on land as other dabbling ducks because their legs are placed further back on their bodies to help propel them when underwater.<ref name=":4" /> Their minimum wingspan recorded is 72 cm, while the maximum is 84 cm.<ref name=":4" />

{{#invoke:Gallery|gallery}}

Distribution and habitat

Rosy-billed pochards nest within tall grasses in wetlands, mainly in areas that extend from the central provinces of Córdoba, Santa Fe, Entre Ríos, and Buenos Aires, southwards to Río Negro.<ref name=":6" /> Individuals are also found in shallow freshwater swamps, marshes and small lakes.<ref name=":3" />

They are a fully migrant species and their movements are heavily associated with water conditions.<ref name=":5" /><ref name=":7">Template:Cite web</ref> Seasonal dry periods are common in central Argentina and they force birds to move towards larger water areas in late summer. By early fall, these areas are often dry and individuals are forced to move to find more water and better food sources elsewhere.<ref name=":5" /> An increase in population size can be seen during wet periods.<ref name=":5" />

Behaviour

Rosy-billed pochards are highly sociable ducks and may congregate in flocks of thousands of individuals.<ref name=":3" />

Diet

Rosybills are omnivorous ducks, feeding on mostly knotgrass and barnyard grasses, but also roots, sedges, aquatic plants and other grasses and some animal products.<ref name=":3" /><ref name=":6" /><ref name=":8">Template:Cite journal</ref> However, their diet is dominated by seed consumption.<ref name=":6" /> This seed-dominated diet is due to the need to obtain carbohydrate-rich food, which is essential for meeting their thermoregulation requirements for the season.<ref name=":6" /> The seeds are high in energy, and this energy is also important for controlling temperature stressors.<ref name=":6" /> Though they are classified as diving ducks, they feed by dabbling on the surface of the water, upending in shallow water and occasionally grazing on land, but they rarely dive.<ref name=":3" /> Since the rosybill has a relative general diet and does not depend on a single food source, the species is said to be relatively adaptable to the offer of alternate food sources.<ref name=":6" />

Reproduction

Each breeding season, a male and female rosy-billed pochard will form a seasonal bond.<ref name=":3" /> The pairs, however, are not monogamous and they do not pair for life.<ref name=":5" /><ref name=":3" /> A distinct spring courtship period exists during which courtship displays are important.<ref name=":5" /> The courtship displays are performed before breedings and consist of distinct movements performed by both sexes.<ref name=":3" /> The displays include exaggerated drinking activities, mock preenings, head bobbings and neck extensions.<ref name=":3" /> Breeding generally occurs in October to November and can be done in single pairs or in small groups.<ref name=":3" />

Females construct nests using plant matter and they line the nest with down.<ref name=":3" /> Nests are normally built over the water at the edge of the water.<ref name=":3" /> Females have also been observed to make their nests in rice fields.<ref name=":6" />

The female lays up to 10 cream to greenish coloured eggs and she may even lay her eggs in another bird's nest if available.<ref name=":3" /> Eggs are incubated for 27-29 days, and fledging occurs within 50-75 days.<ref name=":3" /> Females will raise the ducklings without help from the males.<ref name=":3" /> Occasionally, broods from different females will merge and females will raise the young as a collective.<ref name=":3" />

Vocalizations

Template:Birdsong Similar to almost all other bird species, rosybills have different calls used for different purposes. The characteristic 'honk' of family Anatidae is obvious in this pochard's vocalization, however it is much deeper as compared to a mallard, for example. Based on limited recordings of vocalizations, it appears as if the vocalization of the rosey-billed pochard is relatively quiet.<ref>Template:Cite web</ref>

Use by humans

Rosy-billed pochards are commonly used by humans for consumption, as pets/display animals and even in horticulture.<ref name=":7" /> The species, has been indicated as a pest in rice fields, and they experience a large amount of pressure from hunting in Argentina.<ref name=":5" /><ref name=":6" /> Not only does this pressure stem from the direct hunting of the birds, but also from lead poisoning. Lead shot is the only available ammunition in Argentina, and investigations into lead toxicosis is still very recent.<ref name=":8" /> A 2013 study looking into lead pellet ingestion and tissue levels in ducks from Argentine hunting spots discovered that rosy-billed pochards were more prone to ingesting lead shot than any other duck species they sampled.<ref name=":8" /> Rosybills will swallow the lead bullets thinking they are stones, which are required for the mechanical breakdown of food within their gizzard.<ref name=":8" /> Not only were the bullets found inside the gizzard, but there were traces of lead concentrations within their bones, which is very toxic and detrimental to the health of the bird.<ref name=":8" /> This threat of lead poisoning from hunting has led researches to believe that populations could be declining due to excessive hunting.<ref>Template:Cite journal</ref>

Ownership of individuals is relatively accessible and they can be purchased even online.

Conservation status

Current population trends show that populations are increasing and are not severely fragmented.<ref name=":7" /> There is currently no action recovery plan, however there is a systematic monitoring scheme in place.<ref name=":7" /> Conservation sites exist across the entire range of rosybills and they occur in at least one protected area.<ref name=":7" />

External links

• Video of rosy-billed pochard couple