New Zealand's fruit-eating birds play an important ecological role in the dispersal of seeds of podocarp trees, and broadleaf trees and shrubs. The job they do is essential in sustaining healthy existing forests, and regenerating new forest. Before humans arrived in New Zealand, the flora of fleshy-fruited plants evolved on an isolated land mass for over 70 million years with no terrestrial mammals, apart from three species of small bats, the only other animals other than birds, that could eat fruit whole and disperse the seeds. As almost completely frugivarian, pigeon are the best dispersers of seeds, with the capability of swallowing and digesting the largest karaka and hinau fruit, and the fruit of another 13 trees and many other plants.
Once abundant throughout lowland forests, endemic kereru have followed a similar decline to that of all New Zealand native birds. As a frugivorous bird mainly reliant on the fruit of native plants, kereru populations have decreased as forests were removed. It has also fell victim to a long history of hunting, being one of the largest forest birds, and plump and palatable when gorging on seasonal fruit. It is the seed disperser of 16 large native trees. Kereru play an important role, consuming fruits of at least 70 plant species and excreting the seeds. See more
The parea is only found in the Tuku Nature Reserve and in forest remnants on Chatham Island. The number of birds got as low as 40 in 1986. Parea made a remarkable recovery, mainly because of predator and hunting control, and by 1996 there were about 200 birds. Hemiphaga chathamensis is distinguished by its larger body size, shorter wings and tail, and other appearance and structural differences from Hemiphaga novaeseelandiae which is widespread throughout the mainland and other offshore islands. See more
Silvereye are prolific fruit-eaters - often only the flesh but also whole fruit. They disperse kohekohe and supplejack vine fruit which have a diameter of 9mm and 10.5mm. Its' maximum gape opening of 6.3mm, and mean gape of 5.1mm is the smallest of the fruit-eaters. It has been seen swallowing fruit with a diameter of 9.9mm, 1.9 times the size of its gape. Silvereye are 12cm long, the smallest tree seed-disperser. It is a recent immigrant, first recorded in 1832, probably after a trans-Tasman Ocean storm crossing. See more
Stitchbird (Hihi)Notiomystis cincta
The stitchbird's main food is nectar from the flowers of 20 native plants, and the fruit of 30 species, including two coastal trees karaka and kohekohe, supplejack vine, Coprosma species, five finger, pate and tree fuchsia. Its' maximum gape opening of 8.6mm is close to that of the bellbird, and the mean gape is a bit larger at 7.1mm. The stitchbird is rare and nationally endangered - the only member of the Notiomystidae family, which is endemic to New Zealand. It was reduced to only one Little Barrier Island population, however, it has been reintroduced to three offshore islands and two mainland locations.
The saddleback is the strongest survivor of New Zealand's wattlebirds, mainly because it is now only on offshore islands that have been cleared of predators. Until a century ago, both the North and South Island subspecies were common throughout podocarp forests on both mainland islands. The fruit of kohekohe Dysoxylum spectabile, which has a diameter of 9mm, can be swallowed whole by saddleback even though its gape may be as low as 7mm.
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Along with kereru, tui are a principal disperser of seeds, feeding on the fruit of 10 large native trees, including karaka which has one of the largest fruits up to 17.5mm in diameter. Other fruiting trees for tui include tawa, puriri, miro, titoki, pigeonwood, black maire, matai and kohekohe, together with smaller Coprosma and Pseudopanax species. It is also an insect eater, but mainly a nectar feeder, having a great time and playing an important role in the pollination of kowhai, pohutukawa, rata, kahikatea, rewarewa and flax. Tui are one of the finest songbirds with a radically varied repertoire of cackles, barks, clicks and bell-like musical notes. See more
Kokako consume the fruit of 12 trees and supplejack, but are not a significant seed disperser because of their very limited range. Despite its maximum gape opening of 16.5mm, and mean of 15.3mm, it can swallow the largest native fruit of taraire, which can grow to a diameter of 19.6mm. Kereru is the only other taraire fruit-eater. Kokako also disperse the seeds of tawa, puriri, miro, titoki, mangeao, black maire, pigeonwood, matai, hinau, kohekohe and nikau trees. Kereru feed on all of these plus karaka, tawapou and swamp maire. See more
New Zealand bellbirdAnthornis melanura
Kereru, tui, bellbird and silvereye are responsible for 84 percent of native fruit dispersal. Bellbird disperse the fruit of two podocarp trees, miro and matai, as well as pigeonwood, and the supplejack vine. Its' maximum gape opening is only 8.5mm, and the mean is 6.5mm, but it has been reported to have swallowed fruit that may be as much as 9.7mm in diameter. The bellbird is also an insect and nectar feeder, pollinating some of the same plants as tui. Bellbirds have a beautiful song, liked so much by the tui that it imitates it.
North Island brown kiwi have been observed feeding on the fruit of three native tree species, miro which has a fruit diameter of 13mm, and hinau and nikau which are 9.2mm and 9.1mm in diameter. Kiwi have a varied diet of small invertebrates, seeds, many varieties of worms, fruit, small crayfish, and amphibians. While brown kiwi have the largest gape (24mm) of any New Zealand extant terrestrial bird, it does not consume the largest tree fruit. Because it is flightless, it is restricted to fruit on the ground. See more
The weka is an endemic flightless rail that was abundant until the 1980s, but has since been in rapid decline. Surveys in 1991 and 1995 of the main population in the Gisborne region show only 1500 birds. It is New Zealand's odd bird out since it is a predator of the eggs of other birds. Weka disperse seeds from the fruit of miro, pigeonwood, matai, hinau and kohekohe. Its' gape is 13mm wide, a millimetre smaller than kereru, however, weka have not been observed swallowing whole fruit larger than miro which is the same width as its' gape. See more
Other minor native frugivorian birds
Other native birds that are minor frugivores, but may not be significant seed dispersers, include the New Zealand robin Petroica australis, yellowhead Mohoua ochrocephala, whitehead Mohoua albicilla, brown creeper Mohoua novaeseelandiae, pied tit Petroica macrocephala, fantail Rhipidura fuliginosa, grey warbler Gerygone igata, and rifleman Acanthisitta chloris. Their gapes are all 5mm or less in width.
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