Lyrebirds, famed for their mimicry, are also forest farmers, finds new research

The superb lyrebird, famous for its extraordinary ability to mimic practically any noise, has now been shown to be a resourceful farmer, raking the forest floor to create the ideal conditions for its invertebrate prey. The birds perform this ‘farming’ behaviour at a scale unprecedented in non-human vertebrates. The findings are published in the British Ecological Society’s Journal of Animal Ecology.

Researchers from La Trobe University, Australia, have conducted a three-year experiment showing how the floor raking behaviour of the superb lyrebird boosts the size and diversity of the worms, centipedes and spiders that make up its diet.

The lyrebirds’ raking behaviour benefits invertebrates by creating a mosaic of exposed soil and mixed litter, the ideal conditions for them to thrive.

The researchers recorded lyrebirds moving an average of 155 tonnes of forest litter and soil each year through this ‘farming’ behaviour, meaning that the birds are altering millions of hectares of forest ecosystem, a scale that they say is unprecedented in non-human vertebrates.

Lead researcher Dr Alex Maisey said this type of ‘farming’ from an animal was rarely seen in nature. "Lyrebirds set up the perfect home for their prey, creating conditions with more food resources and effectively fattening them up before eating them."

The researchers also say that this ‘farming’ behaviour could have wider environmental impacts, such as lowering the intensity of bushfires by burying leaves and branches that fuel fires.

“This farming mutualism is playing out across millions of hectares of the eucalypt forests of eastern Australia. Lyrebirds turn over the entire forest floor every ~20 months, maintaining dynamic microhabitats, shaping plant germination patterns, and even altering fire behaviour under mild conditions.” said Alex.

“Without the lyrebird, these forests would be vastly different - poorer in biodiversity and less resilient to disturbances like fire. Understanding and protecting these natural ecosystem engineers is crucial for maintaining the health of our forests for future generations.”

In the study, the researchers set up three types of experimental plots throughout forests in the Central Highlands of Victoria, Australia, where they manipulated the lyrebirds access. In the first type of plot the lyrebirds were excluded (control), in the second lyrebirds were also excluded and the researchers turned to mimicry themselves, simulating foraging using a hand rake (raked), and in the third lyrebirds could forage naturally (natural).

In the raked plots they found larger and more diverse numbers of invertebrates compared to control plots, while there was no change in the natural plots due to predation. The results show that the lyrebird's engineering activities promote a positive feedback loop, replenishing their prey.

Lyrebirds are ground-dwelling birds native to the eucalypt forests of south-eastern Australia. They’re famed for their ability to mimic other birds and even sounds from the human world including camera shutters, car alarms, and chainsaws.

The researchers say that despite growing attention to the role of animal ecosystem engineers, knowledge is still patchy and likely underestimated, especially for groups such as birds and reptiles. Behaviours like the lyrebirds ‘farming’, that dramatically alter environments, may be more common than we think.