NORTHLAND

- What nesting birds tell us about our environment.

My little place here is surrounded by a mix of mature trees and smaller shrubs that are perfect for nest sites, and already the dawn chorus is getting louder as local birds return to the nesting places of their ancestors. The spring season prompts their ancient nesting instinct and their dedication to the task is truly driven, and I was recently treated to an intimate peek at two exquisite bird-built cocoons.

The first was a bird treehouse that I accidentally exposed when pruning a hibiscus. Its sack-like structure was engineered from woven grasses, mosses and lichen artfully suspended from two thin branches, and it was built by a tiny bird because the entrance was less than 20mm wide. Inside, it was lined with luxurious white down feathers, so soft that I wanted to downsize and crawl in there to sleep. I’ve since learnt it was the nest of our tiny grey warbler (riroriro) and when I found this one, the chicks had already flown.

The second nest was an open bowl shape with a sturdy grass-stem structure. Sadly it had fallen from a palm tree but this meant I got to see the artistry of its feather-lined interior. I left the nest outside overnight where it had fallen. By morning all the feathers had been quietly removed and recycled for another avian artwork somewhere.

Even more intriguing has been watching sparrows enter the open top of dead standing ponga trunks with nesting materials in their beaks.

This has happened each spring for the last four or five years – they build nests in these seemingly exposed hollow tubes. A few weeks later, adults make repeated visits to the ponga with food, perching on the open rim to survey the surroundings for safety before disappearing down the tube. Later still, high pitched nestling screeches echo from inside the dead trunk, and the trunk even sways sometimes from the movements inside. Eventually, fledgling birds teeter on the edge of the ponga rim, take their first flying lessons to the deck rail, and the local sparrow population noticeably swells for another season.

The top of one of these ponga trunks is at the same level as my window so I can watch and hear the cycle unfold. Neither of the two ponga has any foliage covering so the trunk tops are literally open to the skies. But because repeated generations of sparrow are successfully raised there, the inside of the trunk must be sculpted with knobs, shelves and protrusions that provide protection from the weather. The sad sequel to this story though is that midseason, mynas or parakeets sometimes colonise the nest, leading to the demise of the young sparrows.

On the other side of the house, both the birds and the nests are considerably bigger. The large white-faced herons have made the pōhutukawa tops their home. They glide in pairs in elegant outstretched flight, but their graceful vibe is then shattered when they announce their arrival with their raspy discordant croaks. They have a meet-up ritual involving a lot of cooing and chatting, and their nest is a precarious platform wedged between branches with construction detritus dangling below it.

Further away, in a pōhutukawa hanging over the bay, a pied shag colony has created its own neighbourhood. These big seabirds like to hang out together so their scrappy nests of sticks all share the same tree year after year. Eventually the buildup of acidic droppings kills the tree and they move their village to a fresh unsuspecting tree.

Other birds we see include tūī, thrush, kererū, blackbirds, pīwakawaka (fantail), quail and tauhou (silvereye), so there are probably plenty more hidden nests in the rewarewa, pseudopanex, bamboo and palms, as well as burrows in the ground for the kiwi, holes in clay banks for the kingfishers, and mud huts in the roof of the sea cave for the swallows. Bird nests are apparently good luck for everyone who lives nearby, so we’re warmly welcoming all the feathered spring arrivals in the hood.