Then it's out, with a quick hop, to the bath's edge to do the Twist, shaking from the tail feathers to the head and sending a fine mist of water driblets and droplets into the air.
For the finale it does something rather odd, at least you might think so, for this is a bird after all: the tui hops to the nearest tree branch to rub one side of its head against the bark. Another hop to another branch is made to repeat the same trick, this time rubbing the other side of the head. Up, up, it goes, repeating this, until at last flying back to begin the whole mad operation, belly flop and all, once again.
Watching this from just three metres away on a breezy but piping hot midweek afternoon on Tiri, I could not help but laugh like, well, not the poor old laughing owl - it's extinct - but certainly like a happy tui.
If I couldn't stay for the endless bath-time encores - the boat back to Auckland was soon to cast off - I could leg it down the track to the wharf knowing that this treasured island had saved one of its best shows for last.
Our native birds have, in recent times, become oh-so-trendy with certain noisy city squawkers. But this should not dissuade the rest of us from visiting Tiri, a sanctuary for our natives perched just off the tip of Whangaparaoa Peninsula.
The island embodies an older, deeper, more durable love of our flora and fauna. And the sheer variety of birdsong that peals through the island's regenerating bush and chimes about its dells and its shady gullies, is a tribute not to the work of a few shrill Johnnies who came lately but to thousands of nameless, committed volunteers who, over decades, have quietly and assiduously begun bringing Tiri back to life.
It was an idyll once. But from the mid-19th century until the 1970s, the 220ha island was farmed, the bush and birdlife quickly wiped or pushed out so that cattle might be fattened. Gazetted as a scientific reserve in 1980, a plan was drawn up by public and private groups to remake the island. For a decade from 1984, volunteers replanted Tiri, now a Department of Conservation scientific reserve and sanctuary, with more than a quarter of a million natives. As the island bush flourished once more, birds returned and some 11 varieties were introduced, including the little spotted kiwi and takahe. According to the Supporters of Tiritiri Matangi (STM), 78 species of bird have been sighted on or close to the island. There are tuatara too.
Tiri will undoubtedly be an idyll again - the island is apparently considered one of the world's most successful conservation projects. But for now, the tourist who likes a bit of a walk can see and hear more species of our birdlife in a day than they will in almost any other place in New Zealand. And there are plenty who do. Around 20,000 people visit Tiri each year, according to DoC.
Those with a boat or kayak (the island is just 4km off Whangaparaoa) are permitted to land on the island. The rest of us must get there by a pleasant 75-minute ferry ride, though at no small expense - the full adult fare from Auckland is $66.
Arriving at the island's wharf, situated just south of Hobbs Beach (named for a family who farmed the island), you may do what you like upon landing. On a previous visit I hoofed it as soon as I was ashore to escape my fellow tourists. This time I took the tour.
The saddleback is a boisterous sort of bird. With a song that sounds for all the world like a car's starter motor cranking over - though rather more tuneful obviously - you won't miss hearing it. It is among the most commonly seen on Tiri too. Indeed it's the first our group of six, led by an S™ guide, spots in the bush around Hobbs Beach.
The less rambunctious birds are no less easy to hear or see, though inevitably you won't see nearly all the species that live on the island (a reason to return). During our two-hour guide, we walked (though there was much stopping) along the Hobbs Beach and Kawerau tracks. We saw and heard whiteheads, male and female stitchbirds, kereru, North Island robins and, of course, fantails and tui. Taking the tour (it costs just $5 and our guide kept up a very informative chat about what we were seeing and hearing) still allows for plenty of sightseeing, however.
As the rest of the group headed back to Tiri's southern tip to its lighthouse and visitor centre, I set off for the eastern bays.
The birdlife seems less abundant on this side - though you will certainly see the awkward, hilarious pukeko - but the bays themselves must be among the most beautiful in the Hauraki Gulf. From Northeast Bay (a perfect spot for lunch and a dip) the track falls and rises through bush and grasslands as you pass Pohutukawa Cove, Fishermans Bay and Emergency Landing before the track takes you to the lighthouse, visitor centre and DoC's small HQ (visitors wanting to see kiwi can book nights at its bunkhouse at $24 for adults and $18 for children).
Best to dawdle, I found. On the grassy cliffs above these glorious bays, facing a cooling easterly breeze, you can sit looking outwards to Coromandel's Cape Colville, and to Great Barrier Island, and wonder about the big questions, like: do tuis mind you watching them take a bath? The answer, of course: "yeah, right".
Titirangi Matangi
* Ferry departs Pier 4, Auckland at 9am and Pier Z, Gulf Harbour Marina at 9.50am Wednesday to Sunday and leaves Tiri at 3.30pm. See www.360discovery.co.nz
* Further information on the island can be found at www.tiritirimatangi.org.nz and www.doc.govt.nz. See the latter to book for DoC's bunkhouse.
* The island's visitor centre offers complementary tea and coffee but sells souvenirs and cold drinks only. Visitors are advised to bring their own lunch and snacks and must carry all their rubbish back to the mainland.
