Yellowhammers (Emberiza citrinella) were introduced to both the North and South islands from the 1860s, and spread quickly. By the early 20th century they were such a problem to farmers that bounties were offered. They are no longer a serious pest.
Distribution and habitat
The natural range of yellowhammers is from Britain to Siberia, some migrating further south in winter. In New Zealand they range from sea level to 1,600 metres, and live in farmland, orchards and tussock country. They feed on seeds, cereal grains and invertebrates.
Yellowhammers, at about 16 centimetres long and 27 grams in weight, are similar in size to sparrows. Males have a bright-yellow head and face, and streaky reddish-brown wings and chest. Females are paler, and have a continuous brown curve from eye to chin. They dip as they fly, closing their wings momentarily.
They build their nests on the ground or in low, thick vegetation, and lay about four whitish-pink eggs with fine scribble lines, which are incubated mostly by the female.
The cirl bunting (Emberiza cirlus) was released in small numbers – seven in Otago in 1871 and four in Wellington in 1880. It has remained uncommon, with a population of just 2,000–5,000 birds. They live in the north-east South Island and eastern North Island.
The cirl bunting is native to southern Europe, North Africa and Turkey, but its hold there is tenuous, so the small New Zealand population is significant.
A close relative of the yellowhammer – and similar in size – the cirl bunting male has a black head with yellow lines above and below the eye, and a black throat and collar. The female is a pale yellow, with darker-brown face markings.
Cirl buntings build nests in low bushes or trees, and lay three bluish-green eggs with fine black streaks.
The dunnock (Prunella modularis) is also called a hedge sparrow, although it is not a true sparrow.
Several hundred dunnocks were introduced on both islands from 1867 onwards, and soon became widely established, including on the offshore islands. They range from sea level to subalpine shrublands, but are sparse in some lowland regions.
The male and female dunnock resemble the female house sparrow in colour. However, they have brown-flecked cheeks and flanks, a slimmer body and a finer bill – which is typical of insectivores.
Habitat and feeding
Dunnocks frequent gardens, orchards, scrub and plantation forests. Because they eat mainly invertebrates, they are more popular with farmers and gardeners than most other small introduced birds. They are secretive, staying close to cover.
In England polygamous breeding is common, but in New Zealand simple pairs are more usual. They build their nests in dense hedge-like bush, and lay four deep-blue eggs.