Preserved droppings may help find new food sources and habitats for the kakapo (Strigops habroptilus), a critically endangered bird native to New Zealand.
These large flightless parrots are like the pandas of the avian world, says of Manaaki Whenua – Landcare Research in New Zealand. “They’re very adorable and very difficult to get to breed,” he says.
The mossy green birds used to live all over New Zealand, but their populations were devastated by the introduction of rats, cats and stoats. By the 1990s, there were only 51 kakapos left.
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Extinct on New Zealand’s two main islands, the remaining kakapos live on a few predator-free islands. The parrots now number some 250 and they are starting to run out of room, says Boast.
Conservation workers are considering new spots to establish populations, so they need to know which foods can sustain the birds and allow them to reproduce.
Boast and his colleagues looked at preserved droppings for clues about the plants the birds ate in the past. The researchers collected hundreds of coprolites from spots, such as caves, where the parrots were known to roost. The team also had access to hundreds of frozen scats, some dating back to the 1950s when conservation for the birds began. They identified plants from microfossils and DNA in the stool samples.
Overall, the team found dozens of plant families not observed in the diets of modern kakapos. For instance, kakapos in some habitats were eating a lot of southern beech, a major genus in much of New Zealand’s surviving forests. “We’ve got another kind of environment that would be really, really good for them,” says Boast.
The findings significantly improve our knowledge of kakapo diets, says , a former scientist at the New Zealand Department of Conservation who wasn’t part of the work. But the variety in their diet isn’t altogether surprising, he says. The birds must have had a broad diet because of their past geographic range and because those relocated to new habitats have managed to feed themselves.
Some scientists suspect that certain foods create hormonal cues that trigger kakapos’ breeding behaviour. The birds are known to breed when coniferous rimu trees mast, dropping all their seeds at once and producing a flood of food. Preserved droppings may reveal that other foods – such as the southern beech, which also masts – can trigger kakapo reproduction, Boast and his colleagues suggest.
But the rimu and southern beech are unrelated, says Moorhouse. It is more likely that the birds breed when they identify a food source that is nutritious and abundant for them to raise young on, he says. Still, the approach of analysing the DNA in droppings could help track what kakapos consume and correlate diet with breeding for newly established populations, he says.
Frontiers in Ecology and Evolution
