For the first time, ancient DNA from droppings left by New Zealand’s flightless moa identifies actual species of fungi the doomed birds ate.
The snacks, including purple lumps of a trufflelike fungus, might have been berry mimics, says paleoecologist Alex Boast of Manaaki Whenua–Landcare Research in Lincoln, New Zealand. For fungal spores inside the lumps, getting gulped by a bird could beat just drifting on some air current to find new homes, Boast and colleagues propose January 15 in Biology Letters. Hitchhiker spores in a bird gut would have been carried into new territory and excreted or, as Boast puts it, “deposited in a rich growing medium.”
Fungi are crucial to the health of forests. So getting an idea of what fungi the now-extinct moa ate helps the team figure out how New Zealand’s unusual ecosystems worked before humans arrived around the 1300s. “The last large landmass colonized by humans,” Boast calls it. Humans were a shock.
New Zealand has no native land mammals, except bats. Instead the island had big birds playing the roles of big foragers. About nine species of ostrichlike moa of different sizes and food interests stalked the islands. Lumps of their hardened poop in various shapes and sizes, one even showing a moa footprint, are still scattered across the country. The best troves of such coprolites lie in what Boast calls “natural refrigerators,” the caves of New Zealand’s South Island.
Boast and colleagues have analyzed tattered remains of DNA in coprolites from upland moa (Megalapteryx didinus), using them as paperweight-sized time machines. In a way, moa did the sample collecting needed to study New Zealand’s past flora and fauna. The team’s earlier review of bird droppings, published in 2018, found remains of ferns, mosses and parasites, as well as fungi. The researchers have since refined their methods to get a better look at the fungi.
Now there’s enough detail in some cases to identify species. One is the trufflelike Gallacea scleroderma with its bright purple lumps encasing the spores. In New Zealand’s low-mammal world, maybe fungi evolved lumplet forms that enticed moa to eat and disperse their spores. In all, the team identified 13 different kinds of fungi in the ancient guano.
Hitchhiking inside birds may also have evolved in the low-mammal landscape of Patagonia, says mycologist Marcos Caiafa of the University of Florida in Gainesville. Patagonian bird droppings, he and colleagues announced in 2021, carry fungal spores, including some from a trufflelike species that wraps its spores in purple.
The New Zealand results have Boast worrying about the future of forests there. Many of these fungi have a lifestyle called ectomycorrhizal, or ECM. We daylight-dwelling humans tend to think of fungi as parasols, puffballs and fuzzes bursting into daylight. Usually these are just the spore-dispersing devices pushing into air currents for spore spreading. The main bodies of most fungi lie out of sight.
Much of a fungus is gossamer filament. Almost internet-like, they thread a forest. In their search for food and water, ECM fungi, such as the ones from moa coprolites, infiltrate living plants pressing against (though not into) individual plant cells. These ECM fungi may be invisible to a human looking at a tree, but they affect water uptake, forest regeneration and lots of woodsy life.
Without moa to disperse these fungi to bald spots or cleared land, Boast says forests probably aren’t as resilient as they once were. And in our times of change, resilience matters.