“[The kakapo boom was] like a heartbeat: a deep powerful throb that echoed through
the dark ravines. It was so deep that some people will tell you that they felt it stirring in their gut
before they could discern the actual sound, a sort of wump, a heavy wobble of air.”
From ‘Last Chance to See’ (1990) by Douglas Adams & Mark Cawardine
The kakapo is the world’s only flightless parrot and originally inhabited a variety of habitats throughout New Zealand. It is also the heaviest species of parrot and is nocturnal. Presently, the kakapo is probably best known for the fact it is battling extinction–at last count only 123 birds were known to still be in existence. Perhaps less well known is the fact it is the only flightless bird with a lek breeding system.
Kakapos only breed once every two to five years, coinciding with the exponential fruiting years of certain tree species. During the courting season, males travel up to 7km from their home ranges to establish their mating courts on hilltops and ridges, usually about 50 metres apart within the lek arena. Males remain here throughout the season, initially fighting to win the best courts, which leaves some birds injured or even dead.
Tracks, Bowls and Booms
Each court comprises at least one “bowl”—a depression dug in the ground, up to 10cm deep and long enough to fit the bird’s half-metre length. Often, bowls are created next to tree trunks, rocks or banks to amplify the male’s “boom”, or mating call. Each male’s bowls are linked by a network of tracks extending up to 50 metres along a ridge or 20 metres in diameter around a hilltop.
Researchers can tell which sites are used each night by leaving a few twigs in the bowls because, if visited, the male will toss them away with his beak as he carefully clears large areas of his stomping ground.
To attract females, males stand in their bowls making loud, low-frequency booming calls (below 100 Hertz) using an inflatable thoracic sac. Starting with low grunts, the volume increases as the sac inflates. Then, after a sequence of about 20 booms, the male emits a high frequency, metallic “ching”. He pauses briefly before lowering his head and inflating his chest again to begin another sonic sequence.
These booms can carry up to 5km on a still night. Males boom for six to eight hours a night, each producing thousands of booms in one night. This may continue nightly for three to five months, over which time a male can lose half his body weight.
Females walk up to several kilometres from their territories to the lekking arena, attracted by the competing resonant booms. Upon entering a male’s court, the courtship display begins—he rocks from side to side, clicking his beak, then turns his back to the female, spreads his wings and walks backwards towards her. Once they have mated, the female returns to her territory to nest and raise the chicks. The male continues booming in the hope of attracting another female.
Rehabilitation Program
“The net result of all these months of excavating and booming and walking and scrarking
and being fussy about fruit is that once every three or four years the female kakapo
lays one single egg which promptly gets eaten by a stoat.”
From ‘Last Chance to See’ (1990) by Douglas Adams & Mark Cawardine
The long range of the males’ booms also attracts predators, as does the kakapo’s musky perfume, and the species’ demise has been caused mainly by introduced animals, such as cats, rats, stoats and dogs.
In 1995, the total population dwindled to 51 birds. Fortunately, the “night parrot” appears to be making a comeback with intensive efforts by New Zealand’s Department of Conservation to protect and manage breeding populations. From 1998 to 2001, major rat and stoat eradication programmes enabled Codfish and Anchor Islands to be declared predator-free zones and therefore long-term kakapo sanctuaries. By 2003, the overall population had increased by 68 per cent.
Thus far, the Kakapo Recovery Programme has been deemed a success, with 33 chicks raised in 2009. Happily, the kakapo’s boom should continue to beat loud and clear, and may one day even be heard on the mainland again. Two chicks were recently born from artificial insemination, so luckily, the kakapo’s future does not hang entirely upon its unique mating system.
