KEY POINTS:
Conservationists believe they may have discovered an avian aphrodisiac which could save the kakapo.
One of the world's most endangered birds, the kakapo number only 86.
The parrots are notoriously infrequent breeders, mating only once every three to five years.
But Auckland University nutritional ecologist David Raubenheimer hopes his new bird seed may pep up the birds' sex lives and boost their numbers.
Professor Raubenheimer is testing the feed developed with the Department of Conservation which aims to more closely resemble the nutritional make-up of rimu fruit.
He had observed that the female's breeding years tend to coincide with the years in which the trees fruit most heavily.
"The obvious conclusion was that there's something about the nutrition provided by these rimu fruits which is triggering and sustaining reproduction," he said.
DoC used a feed high in proteins, made for pet parrots, to supplement food in its kakapo colonies.
It was based on the belief in the 1980s and 90s that lack of protein affected reproduction in the wild.
Professor Raubenheimer said: "The thing about kakapo is that they're not typical parrots. Unlike any other parrot, they're strictly herbivorous. This means that a food that might be good for other parrots might not equally apply to kakapo."
He started to look at the nutrient composition of the feed, and that of the rimu fruit, after being asked to take part in a DoC workshop in 2005.
He found the current feed to have more protein and energy than would be found in the fruit, and significantly less calcium, a vital mineral in bird reproductive health.
Most species - human beings included - regulate their food intake most strongly according to their consumption of macronutrients such as proteins.
"What that means is that once you've had your fill of protein, you tend to have your fill of food. So in these high protein diets, I was able to calculate that if these animals were actually feeding to their fill of protein and then stopping, they would be getting a considerable shortage of calcium."
He and DoC kakapo specialist Ron Moorhouse are now testing special pellet feeds on DoC's kakapo population on Codfish Island, about 3km off Stewart Island.
The pellets, formulated by Massey University, are lower in protein than the conventional feed, and help bring the overall balance of nutrients more in line with the composition of the kakapo's natural diet.
"Picking enough rimu fruit to sustain a population of kakapo - and they eat a lot of it during breeding season - that's a considerable logistical challenge approaching the impossible."
The birds - notoriously fussy eaters - are taking to new food pellets, despite their larger, harder-to-eat size.
It must be love
* During the breeding season in early summer male kakapo take to prominent ridges, rocks or hilltops with low-growing vegetation to begin a courtship competition for female attention.
* From its high perch, each bird sounds a deep resonant "boom", announcing to any females in the area that he is ready to mate.
* The males compete against each other, and can "boom" thousands of times a night.
* The female kakapo will travel several kilometres to visit the males and mate. But after mating the females are left to tend the nest by themselves - the males just keep booming in the hope of finding another mate.
* The female kakapo lays between one and four eggs, which hatch after about 30 days.
Source: Kakapo Recovery Programme
