One of the loveliest visitors to the Bay of Plenty during the winter, notwithstanding Kotuku, the white heron, is Tarapiroe, the black–fronted tern.
There are numerous terns to be found around the New Zealand coast, from the rare fairy tern to the common white–fronted as well as vagrants and migrants such as the Arctic terns. All the terns, sometimes called sea swallows, are extraordinarily elegant birds but it takes a real expert to distinguish one from the other.
Tarapiroe is a small bird, just 29cm on average in length, but a very stylish bird indeed with its blue grey body and short shallow–forked tail contrasting with the white rump in flight. It displays a stunning combination of just the right tone of grey, topped with a black cap down to the bill which is bright orange like its legs. The outfit serves to remind of how historically we have often been influenced and even mimicked birds in our style of dress and combination of colours — the “penguin” suit or (swallow) tails.
Tarapiroe is a protected rare endemic bird which means it is found only in New Zealand. The population is estimated to be around 5000 and every year the local branch of the New Zealand Ornithological Society checks the numbers of birds which come north to winter with us. This year we observed just a dozen birds at the mouth of the Rangataiki River in the Bay of Plenty which is a few more than we saw last year but were pleased to see juveniles among them which were readily identified as they do not have the black cap.
The black–fronted terns breed on the shingle riverbeds of the South Island from Marlborough to Southland and on the upper Motueka and Buller rivers in southern Nelson. In late summer and autumn they disperse to coastal areas, occasionally reaching Northland and the waters off Stewart Island.
Small wintering flocks of 20-50 birds regularly appear in the North Island at the Bay of Plenty, Hawke’s Bay and at Palliser Bay where they may come ashore to roost in the middle of the day among flocks of white–fronted terns. Tara, the white–fronted tern, is by far the commonest tern in New Zealand waters and are readily identified as they are somewhat larger than Tarapiroe.
They nest in small colonies of up to 50 pairs, some on riverbeds near the coast but most are well inland, often near colonies of Tarapunga, the black–billed gulls. According to W.H.Oliver, “The birds collect on a suitable shingle bank in September and begin to mate. By the beginning of October they are selecting nesting sites, a procedure that takes about a fortnight, although most of this time is spent in play. The making of the nest,” he says, “which consists of a shallow scratching or even a natural depression among the stones, with perhaps a dozen or so short bits of twigs around it, could easily be achieved in an hour at the most.”
Their colonies are easily disturbed by predators and people but they will pluckily attack intruders by diving and calling harshly, often striking an intruders head with their feet. But they are small birds and no competition for intruders such as cats, dogs, and mustelids. Many of their nesting sites have also been invaded by exotic plants such as willows and lupins.
While breeding, they feed in flocks over rivers and nearby fields. The development of farmland beside their nesting sites has created feeding opportunities as they follow the plough to catch insects and worms and grass grub larvae.
Most of their food, however, comes from around the rivers. They work their way up rapidly flowing rivers and return repeatedly to their starting point. They contact dip from about two metres above the water to take mainly emergent nymphs and subimago mayflies and stoneflies. They sometimes plunge dive to take small fish such as upland bullies.
“Often a whole flock will feed on insects at a height of perhaps a hundred feet. Sometimes,” Oliver quotes, “I have watched such a flock, the individual members of which were catching from six to fifteen insects a minute, nearly always rising to take their prey. I put this down to the fact that they could see the insects best against the light.”
After breeding, when most move to the coast for the autumn and winter, they feed by taking mostly planktonik crustaceans from the sea as well as earth worms from coastal pasture. The mouth of the Rangitaiki river with lush farmland nearby would seem to promise comfortable wintering grounds for a small number of them.
Other common names: —
29 cm., 80 g., blue grey body, short shallow-forked tail contrasting with the white rump in flight, black cap in adults down to bill which is orage, legs orange.
Where to find: —
Breeds in small colonies on gravel riverbeds of South Island, disperses to coasts, especially around Cook Strait but as far north as the Bay of Plenty.
Illustration description: —
The Zoology of the Voyage of the Erebus and Terror, Birds, George Robert Gray, 1839-1843.
Heather, B., & Robertson, H., Field Guide to the Birds of New Zealand, 2000.
Oliver, W.R.B. New Zealand Birds, 1955.
Buller, Walter Lawry, Birds of New Zealand, 1888.
Page date & version: —
Thursday, 5 June 2014; ver2009v1