Many farmers have rued the introduction of house sparrows (Passer domesticus). They were intended to help reduce the swarms of crop-eating insect pests. However, while they do feed their nestlings on caterpillars, beetles, flies and spiders for the first week after hatching, at other times they are more interested in grains and fruit than insects. They can cause significant damage to wheat, barley and maize crops.
As few as 100 house sparrows were liberated between 1866 and 1871.
Breeding success was high – probably due to abundant food, lack of competition, a benign climate and few predators (stoats, cats and other introduced pests had not yet become widespread).
Early observers of sparrows noted that females laid eggs for a second clutch while the previous hatchlings were still in the nest. The young ones evidently helped incubate the eggs.
In 1878 naturalist Thomas Kirk calculated that one pair of house sparrows could theoretically lead to a population of 322,000 within five years.
Operation sparrow control
Sparrow clubs were formed in the 1880s with the aim of reducing the sparrow plague. These were modelled on the clubs set up in England from the 1850s. Poisoned grain was laid and a bounty offered for sparrow eggs, which encouraged small boys to collect hundreds of thousands of eggs.
The Canterbury Acclimatisation Society liberated 40 sparrows in 1867. Once sparrows became a pest, the society wished to disassociate itself from any part in their introduction. They popularised the tale that in 1867 a Captain Stevens had arrived in Lyttelton with house sparrows instead of the insectivorous hedge sparrows he was commissioned to bring. The society claimed that they declined them, but that Stevens released the five house sparrows that had survived the voyage.
House sparrows are small birds, weighing about 30 grams and measuring 14 centimetres. They have a short, conical bill, like many seed-eaters. The male has a grey crown and dark chestnut nape and back, with black streaks. In the breeding season he has a large black bib with contrasting pale grey cheeks and belly. After breeding, the bib reduces to a small patch under the chin, and the black bill turns pinkish-cream.
The female has a sandy-brown back streaked with black, and pale grey undersides. She has a buff curved ‘C’ from behind the eye to the neck.
Both sexes have a single white bar on the wing.
House sparrows tend to live in association with humans, often nesting around houses and sheds, or hanging around restaurants. They can spread disease by contaminating human food.
The male builds a bulky domed nest, often in a hole. He renovates the nest periodically, even when not in use. The female lays four or more grey-white eggs with brown spots and streaks.