Story: Small forest birds
Page 4 – Honeyeaters – bellbirds and tūī
The bellbird and tūī belong to the Meliphagidae or honeyeater family.
Bellbirds or korimako (Anthornnis melanura) are beautiful singers. At dawn and dusk they form a rolling chorus that can fill a valley for many minutes. They also sing solo at any time of day. Male and female perform duets, and birds sing against each other to define territorial boundaries. Young birds learn from neighbours, so the tunes vary from place to place, forming a ‘local dialect’. Māori would compare a person’s fine singing or oratory to the korimako as a compliment.
Bellbirds are around 20 centimetres long, and dull coloured – olive and black with a red eye. Males weigh 34 grams and females 26 grams. The males in particular are bossy and intimidate smaller birds. Adults sometimes make a loud whirring noise with their wings as they fly. Females have a narrow stripe from the bill below the eye.
There are three subspecies. One is found on the North, South, Stewart and Auckland islands, one on the Three Kings Islands, and one on the Poor Knights Islands. They are common in many forested areas but absent from others, including Northland.
Male bellbirds defend trees that contain prized foods, refusing access to stitchbirds and even female bellbirds. But they do let in their own mate during the breeding season. Tūī are even more stroppy. They pursue would-be trespassers (including bellbirds), shouting their alarm call, flapping, clacking their bills and even dive-bombing. They sometimes form aggressive mobs.
Bellbirds return to the same breeding territory each year. The female builds the nest and lays up to five pale pink eggs with reddish spots and blotches. She incubates these for 14 days, and leaves the eggs to feed, or is occasionally fed by the male. Chicks eat mainly insects and spiders. They fledge after two weeks, and continue to be fed for another week or two.
The tūī (Prosthemadera novaeseelandiae) has an exceptional vocal range, from harsh squawks, clicks and whirrs to bell-like melodies. Tūī mimic other birds and various sounds from their environment. Part of their range is beyond human hearing, so in the middle of a song they can seem to fall suddenly silent.
Māori sometimes trained tūī to talk, and some chiefs taught their caged birds complex speeches. To help them speak clearly, their brush-tipped tongues were trimmed.
Tūī are dark iridescent green with purple and azure highlights. They have two tufted white feathers under the chin, inspiring their other name, parson bird, as these look like a clergyman’s collar against their dark plumage. Lacy white feathers cover the back and sides of the neck. Males weigh 120 grams, females 90 grams, and they are 30 centimetres long. The Chatham Islands subspecies is bigger.
Tūī breed similarly to bellbirds.
Too many tūī?
The tūī’s name has been used for the Tui Music Awards, and for brands of beer, balms, rental campervans and garden products. The first women to serve overseas in the Second World War were named the Tuis, carrying out canteen duties in New Zealand forces clubs in Egypt.
Spreading pollen and seeds
Tūī and bellbirds are important pollinators of plants, including kōwhai, pūriri, tree fuchsia, flax and kākā beak. They transfer pollen on their foreheads while collecting nectar from the deep throats of these flowers. Only tūī and bellbirds can twist open the flowers of two species of mistletoe.
They also spread the seeds of many plants – including tōtara, kahikatea, mataī, pittosporum and coprosma species, and other plants with fleshy fruit. The birds eat the berry, ‘clean’ the seed with stomach acid, and leave it at a new site with some fertiliser.
Adaptations for feeding on nectar include a curved bill and long, brush-tipped tongue. Nectar and fruit are seasonal, so the birds need other foods. In beech forest, honeydew – a sugary liquid excreted by scale insects living on beech trunks – provides bellbirds and tūī with carbohydrate all year. Both species also eat invertebrates, which can form up to 85% of bellbirds’ energy intake. Tūī sometimes jump and thrash around on plants to disturb large insects.
Both species travel long distances seeking food. In winter they move from small patches of bush into towns, where they feed on garden trees and shrubs that have diverse flowering and fruiting times.