A new study may have found the key to an aphrodisiac needed to kick-start the love life of the nearly extinct kakapo.
Researchers from Massey University have solved the puzzle of why rimu berries are a kakapo favourite, so much so the critically endangered parrots will not bother breeding without access to them.
The scientists have found the berries are particularly high in vitamin D, a nutrient essential for laying eggs and the growth of the bird's chicks.
During breeding, female kakapo will scale trees as tall as 25 metres to collect berries for themselves and their young.
Conservationists have struggled for years to find an alternative food source for the parrots, which simply refuse to breed unless native rimu trees are fruiting heavily.
Researchers had thought the reason was calcium, but the vitamin D discovery means different ways to provide the nutrients can now be revisited.
The results come at a critical time, with only about 125 of the birds remaining.
Aside from their effects on kakapo, the researchers also say the findings challenge previous beliefs that there are no naturally high-concentration vitamin D food sources.