New Zealand Scaup Aythya novaeseelandiae Scientific name definitions

40–46 cm; male 630–760 g, female 530–700 g (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); wingspan c. 60 cm. Only male Aythya that is dark overall with yellow eye  ; no eclipse plumage; upperparts  black, with green  or purple  iridescence strongest on head  , with brownish-black underparts, mottled brownish white over lower breast and belly, and has black upperwing with broad white band  across secondaries, and brownish-white underwing  ; bill bluish black with black nail  , and legs and feet black. Female  has dark brown upperparts, becoming almost black on rump, with dark brown underparts mottled brownish white on lower breast/belly, with wing pattern  like that of male, but has brown iris, brownish-black bill and dark brown legs and feet; white triangular patch  on chin; c. 50% of females have white feathering around bill, especially during breeding season. Juvenile  as female, without white on face  and has whitish abdomen; young male identifiable at c. 6 months old (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ).

New Zealand: fragmented range on North I, but more widespread throughout W South I.

Fairly deep, large, freshwater lakes  and shallow, coastal lagoons , from sea level to c. 1000 m on high ground, including volcanic lakes of variable trophic condition (C North I), high-altitude glacial lakes (South I), lowland peat lakes (West Coast) and hydro-lakes (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Particularly frequent in dams and reservoirs, but few recent records on rivers (such occurrences were apparently frequent in 19th century) (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close , 2 Wood, J.R. and Garden, C.J. (2010). Seasonal variation in duck populations on the Waihopai River, Invercargill, New Zealand. Notornis. 57(1): 57–62. Close ).

Mostly sedentary, with only small-scale movements recorded; winter congregations suggest local movements away from summer breeding localities (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ), with up to 3500–4000 birds recorded in winter on wetlands within city of Christchurch during the 1990s (3 Crossland, A. (1999). Changes in birdlife after wetland enhancement in Christchurch. Notornis. 46(4): 409. Close ).

Apparently mixed diet of aquatic invertebrates, including gastropods and insects (e.g. dragonflies, damselflies, water boatmen and backswimmers) (4 Wakelin, M. (2004). Foods of New Zealand dabchick (Poliocephalus rufopectus) and New Zealand scaup (Aythya novaeseelandiae). Notornis. 51(4): 242–245. Close ), and plant matter, mainly submerged macrophytes. Recent study of gizzard contents of 19 birds from four sites found that snails (Physa acuta, Potamopyrgus antipodarum) were common foods of all birds at two sites, but chironomid larvae were a feature at just one; all of those birds from L McLaren had consumed Trichoptera larvae (Oxyethira albiceps, Paroxyethira hendersoni, P. tillyardi, Hydroptilidae, Triplectides sp.) whereas only half of those at Woodend Lagoon had done so, and in lesser quantities; at L Westmere and L Pouarua snail remains dominated gizzard contents, while small stones were a feature at both Woodend Lagoon and L McLaren and seeds (Potamogeton?) were common to both these two samples too (4 Wakelin, M. (2004). Foods of New Zealand dabchick (Poliocephalus rufopectus) and New Zealand scaup (Aythya novaeseelandiae). Notornis. 51(4): 242–245. Close ). Feeds mostly by diving in relatively shallow water; also chases insects from surface. Diurnal activity budgets poorly known, but thought to feed mainly during late afternoon and at dusk (not at night) (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Regularly forms flocks, those during breeding season presumably of non-breeders (mainly males) (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ).

Considered to be generally quiet, with most vocalizations associated with displays: male gives soft, whistle-like “whe” that can be given singly, doubled or in multiples, whereas female utters high-pitched “errrr” during social interactions and a trilled “whirr whirr” as an alarm to ducklings (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ).

Lays mainly Oct/Nov, rarely earlier, and season can extend until Feb; ducklings mainly observed Dec–Jan (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). In single pairs or loose groups, especially on islands (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); nest is cup-like structure made of reed stems, grass and adjacent vegetation, lined with down, on ground, well concealed among vegetation and sometimes enclosed from above (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ), near water, frequently on islands where available (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Clutch 4–8 creamy white to mocha brown eggs (range 2–13, with larger clutches probably evidence of egg dumping) (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ), laid at c. 1·4-day intervals (in captivity) or c. 29 hours in wild, size 59·3–75·1 mm × 41·6–46·6 mm, mass 59·5–81 g (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); incubation 27–31 days (captivity), perhaps slightly longer in wild, by female alone (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); chicks  have pale brown down above  , brownish or buff-white on underparts, face  and dorsal spots, with brown bill and grey-brown legs and feet, and weigh 43·8 g on hatching (in captivity) (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); leave nest after c. 24 hours and fledge at c. 75 days (captivity), perhaps 7–8 weeks in wild, tended by female , with broods sometimes amalgamating (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Duckling survival sometimes extremely low, just 2·5–4·4% in one study (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Age of first breeding not certainly known, although some captive females breed in first year (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). No data on annual adult survival rates or longevity (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ).

Not globally threatened (Least Concern). Still widespread, though severely reduced during first decades of present century through hunting, which to some extent remains a threat due to inability of hunters to correctly identify legitimate quarry species (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); has disappeared from lowlands since European settlement; subfossil remains demonstrate that species was also formerly present on Chatham Is (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Legal protection since 1934 has permitted recovery process, but this has been slowed down by large-scale drainage of wetlands. Increasing in many areas since 1950s thanks to great adaptability in colonizing artificial waterbodies (e.g. hydroelectric dams on R Waikato) (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Total population estimated at only 5000–10,000 birds, largely restricted to E side of Southern Alps (South I) and N & C parts of North I, where it is only common near Taupo and Rotorua (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ), and on which island a captive-breeding and reintroduction programme has proved very successful. Latter technique is probably needed to enable species to recolonize lowland areas of the country (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ).