The most characteristic sound made by the New Zealand native wood pigeon isn’t a song – since only a relative few hear the quiet coo.
Rather, it is the noise as it crashes through the forest canopy to alight on a branch, or the heavy wingbeats as it heaves its 650 gram body into and through the air that usually indicates a kererū is nearby.
Once seen, this behemoth bird, New Zealand’s sole endemic pigeon species, is hard to forget. Its iridescent blue/green head and back is a brilliant contrast to the freshly laundered look of its white chest and underwings, with bright red legs and bill completing the picture.
This contrast is used to great effect by male kererū during its display flights early in the breeding season. As part of the “courting process”, he will make step upward glides with wings outstretched before stalling, folding his wings and entering an equally steep downwards dive to gain momentum for a repeat. “Wings over Wairarapa” takes on a whole new aspect! Though you are likely to see more graceful dismounts at “Wings” – due to their generous size, kererū are known to snap whole branches under their weight as they land. Kererū are widely distributed throughout the country, and can live in both urban and rural environments.
They are particularly populous in Wairarapa, with birdwatchers witnessing flocks of up to 30 taking wing around the Rimutaka Hill. Large numbers make their home in an area aptly named Pigeon Bush, a 1175 hectare reserve covered in dense forest, between the Rimutaka and Tararua Conservation Parks. You can also spot flocks further north, while taking a trip to Pukaha Mount Bruce.
Though kererū have persisted in good numbers through times of great change since humans arrived, any assessment of their total population is a challenge. Given the birds can live in excess of 20 years, and lay only one egg each breeding season, it is not easy to keep track of new generations – especially as the eggs are often under threat from nest-robbers, such as possums and rats.
Wildlife experts say kererū conservation is vital, as these vivid vegetarians have an important role to play in forest regeneration. Since the moa became extinct, the kererū is the only endemic bird large enough to swallow the large seeds of many native trees and shrubs and disperse them through the forest. Even if the majority of the seeds they ingest are dropped close to the trees that bore them, some will remain in the kererū on their long flights and colonise a new area.
To help keep tabs on kererū numbers, The Great Kererū Count was launched by WWF New Zealand in 2012. For a week out of each year, people are encouraged to seek out kererū and record their observations online (www.greatkererucount.nz). Over the past few years, this has become one of the country’s largest citizen science projects.
In areas where pests are well controlled or removed there is a big boost to kererū numbers. Where a flock of 10 was a rarity, flocks of 40 or 50 become a common enough sight as the birds move between feeding grounds. Kererū are more than capable of flying long distances when there is the prospect of a good food source as a reward. These birds are a gluttonous lot and, though shy, can be coaxed into your garden (for recording, or to be admired) by way of a bird feeding platform. Kererū will generally be attracted to plums and red grapes, though frozen peas and corn can also entice them to come a little closer.
In the wild, kererū subsist largely on the fruit of native trees. Once summer rolls around, they can make quite a spectacle of themselves – as tree fruit exposed to the sun can ferment, kererū, after gorging themselves on their spoils, can become intoxicated and can fall from their perch while attempting to take off.
Attractive, a little boozy, an aerial master, and crucial for the eco-system – kererū are something of a national treasure.
Story by Tony Silbery and Erin Kavanagh-Hall.
Photo by Brian Brake courtesy of Te Papa.