New research shows lyrebirds move more litter and soil than any other digging animal

Male Superb Lyrebird in display.
Alex Maisey, Author provided

Alex Maisey, La Trobe University and Andrew Bennett, La Trobe University

When you think of lyrebirds, what comes to mind may be the sound of camera clicks, chainsaws and the songs of other birds. While the mimicry of lyrebirds is remarkable, it is not the only striking feature of this species.

In research just published, we document the extraordinary changes that lyrebirds make to the ground layer in forests in their role as an ecosystem engineer.

Ecosystem engineers change the environment in ways that impact on other species. Without lyrebirds, eastern Australia’s forests would be vastly different places.

Male lyrebird in full tail display.
Alex Maisey

What is an ecosystem engineer?

Ecosystem engineers exist in many environments. By disturbing the soil, they create new habitats or alter existing habitats, in ways that affect other organisms, such as plants and fungi.

A well-known example is the beaver, in North America, which uses logs and mud to dam a stream and create a deep pond. In doing so, it changes the aquatic habitat for many species, including frogs, herons, fish and aquatic plants. Other examples include bandicoots and bettongs.

The Superb Lyrebird acts as an ecosystem engineer by its displacement of leaf litter and soil when foraging for food. Lyrebirds use their powerful claws to rake the forest floor, exposing bare earth and mixing and burying litter, while seeking invertebrate prey such as worms, centipedes and spiders.

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To study the role of the lyrebird as an engineer, we carried out a two-year experiment in Victoria’s Central Highlands, with three experimental treatments.

First, a fenced treatment, where lyrebirds were excluded from fenced square plots measuring 3m wide.

Second, an identical fenced plot but in which we simulated lyrebird foraging with a three-pronged hand rake (about the width of a lyrebird’s foot). This mimicked soil disturbance by lyrebirds but without the birds eating the invertebrates that lived there.

The third treatment was an unfenced, open plot (of the same size) in which wild lyrebirds were free to forage as they pleased.

Over a two-year period, we tracked changes in the litter and soil, and measured the amount of soil displaced inside and outside of these plots.

A colour-banded female lyrebird in Sherbrooke Forest, Victoria. Her powerful claws are used for foraging in litter and soil.
Meghan Lindsay

Lyrebirds dig up a lot of dirt

On average, foraging by wild lyrebirds resulted in a staggering 155 tonnes per hectare of litter and soil displaced each year throughout these forests.

To the best of our knowledge, this is more than any other digging vertebrate, worldwide.

To put this in context, most digging vertebrates around the world, such as pocket gophers, moles, bandicoots and bettongs, displace between 10-20 tonnes of material per hectare, per year.

To picture what 155 tonnes of soil looks like, imagine the load carried by five medium-sized 30 tonne dump trucks – and this is just for one hectare!

But how much does an individual lyrebird displace? At one study location we estimated the density of the lyrebird population to be approximately one lyrebird for every 2.3 hectares of forest, thanks to the work of citizen scientists led by the Sherbrooke Lyrebird Study Group.

Based on this estimate, and to use our dump truck analogy, a single lyrebird will displace approximately 11 dump trucks of litter and soil in a single year.

Lyrebirds dig up a lot of dirt in forests.

Changes to the ground layer

After two years of lyrebird exclusion, leaf litter in the fenced plots was approximately three times deeper than in the unfenced plots. Soil compaction was also greater in the fenced plots.

Where lyrebirds foraged, the soil easily crumbled and the litter layer never fully recovered to a lyrebird-free state before foraging re-occurred.

This dynamic process of disturbance by lyrebirds has been going on for millennia, profoundly shaping these forests. For organisms such as centipedes, spiders and worms living in the litter and soil, the forest floor under the influence of lyrebirds may provide new opportunities that would not exist in their absence.

Terraced soil where litter has been removed and roots exposed by foraging lyrebirds.
Alex Maisey

An ecosystem ravaged by fire

The Australian megafires of 2019/20 resulted in approximately 40% of the Superb Lyrebird’s entire distribution being incinerated, according to a preliminary analysis by BirdLife Australia.

So great was the extent of these fires that the conservation status of the lyrebird has been thrown into question. That the conservation status has fallen – from “common” to potentially being “threatened” – from a single event is deeply concerning.

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Loss of lyrebird populations on this scale will have potentially far-reaching effects on forest ecology.

In the face of climate change and a heightened risk of severe wildfire, understanding the role that species such as the Superb Lyrebird play in ecosystems is more important than ever.

Without lyrebirds, eastern Australia’s forests would be vastly different places, with impacts extending well beyond the absence of their glorious song to other animals who rely on these “ecosystem engineers”.The Conversation

Alex Maisey, PhD Candidate, La Trobe University and Andrew Bennett, Professor of Ecology, La Trobe University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Let me see you shake your tailfeathers: why lyrebirds really can dance

Hollis Taylor, Macquarie University

Let’s go backstage with an Albert’s lyrebird called George. One winter’s night, I accompanied lyrebird expert Sydney Curtis to record George in Lamington National Park, Queensland. Curtis positioned a microphone on a long lead above a platform of trampled vines that George had previously prepared as his stage. Then, we hid behind two immense trees as dawn approached.

When George arrived, he thrust his magnificent tail over his head and spread it like a fan. He mimicked a number of birds – satin bowerbird, yellow robin, crimson rosella, and kookaburra – as he rocked from side to side on his platform. The dramatic play of light and shadow called to mind the flowing silk costumes of dancer Loïe Fuller, famed for her theatrical lighting techniques.

Then George moved his tail farther forward to envelope himself. Grabbing a vine, he tapped it against another – a simple gesture that set a wide area vibrating. He alternated sections of unmetered song with synchronised singing, dancing, and drumming in strict three-four time. It called to mind the rhythmic sounds of clapsticks and boomerangs that accompany some Aboriginal voice chants.

George put on quite a show – but should we simply be describing this performance as a dance, plain and simple? Or should we, as some scholars do, refer to this as “proto-dance” or a functional gesture? “Signal”, “display”, or “dance-like behaviour” are also common substitutes, as are “moves”, and even “courtship in action”.

A male lyrebird – not George – shimmies and sings to attract a mate.

His hips don’t lyre

There are various objections to describing what animals can do as true dancing.

The simplicity offered by the human cutoff point appeals to some, as does the demand that the aesthetic standards of elite dance be met. Poet and philosopher Paul Valéry felt that dance raises us above our animal existence; he required dance to be impractical.

Philosopher of art Susanne Langer held that animals could not dance because they lacked the intentional mental state to transform their gestures into aesthetic ones. However, many others have rejected the premise that dance is thought-made-visible and that language is an essential condition for culture.

The critique that avian movements are too simple or repetitive to be classed as dance ignores the fact that much popular and folk dance (and music) in the human sphere is also simple, repetitive, and formulaic. Simplicity and repetition are virtues in many genres.

Some argue that because avian dance is merely a bird “taking care of business”: finding a mate. Yes, animals enlist aesthetic qualities to fulfil a practical purpose. Nonetheless, humans (and George’s avian audience) can appreciate how a bird’s song and dance perform their function. Merely “taking care of business” seems unsatisfactory as the sole explanation for them.

Many scholars have also assumed that the capacity for music requires the ability to entrain to (or move in time to) a beat and that only humans could do this.

But in 2009, YouTube sensation Snowball, the dancing sulphur-crested cockatoo, was shown to synchronise to a beat and adjust to a changing tempo, and discoveries of other entraining species soon followed.

George represents an even rarer form of this capacity: self-entrainment. He dances to a beat accompanied by his own self-produced drumming and singing.

What is dance anyway?

Dance is a diverse practice. What does a Hopi bean dance have in common with an Australian corroboree or a striptease? How can any definition accommodate both the Rockettes and classical ballet, or a Hawaiian hula and a Nepalese stick dance?

Nonetheless, whether square, tap, or postmodern “task” dancing, such activities typically find animal correlates.

In fact, animal dance can be straightforwardly described using the vocabulary of human dance. Circle and leap, step and prance, moving forward and back, hopping, stamping, and whirling – all of these are known across a wide variety of species.

For instance, both sexes of the blue-capped cordon-bleu participate in high-speed tap dancing and step dancing.

Birds have inspired innumerable human dances, like the crane dances found in China, Japan, Australia, and ancient Greece. Human dancers both portray animals and appear onstage with them. Matching animal efforts is not without challenge – birds’ abilities exceed ours in many areas (such as migration and hearing resolution and, possibly, in some forms of dancing).

Removing the blinders of human exceptionalism opens up the possibility that animal dance could be fruitful in helping us to probe the biological basis of artistic practice.

Thin, clinical language diminishes our understanding of animal achievements. Interestingly, Charles Darwin revelled in using vivid human-animal metaphors, without scare quotes. In 1871, while drawing a comparison with mankind, Darwin credited birds with “strong affections, acute perception, and a taste for the beautiful”.

George is not a robot. As a songbird, he must spend many hours learning and rehearsing his song and dance; they are not innate.

While some of his dancing corresponds to the unpredictable rhythm and movements familiar in postmodern dance, at other times he dances in a clear and steady rhythm that demands still other fine motor skills.

Vocalist, composer, stage designer, and dancer – this Albert’s lyrebird is a multi-modal performer.

The Conversation

Hollis Taylor, Research Fellow, Macquarie University

This article was originally published on The Conversation. Read the original article.

2015 Lyrebird Survey Report

Friends of Tarra-Bulga National Park

We always cross our fingers and hope for favourable conditions on the morning of our annual Lyrebird Survey which this year was held on Saturday May 30th.  This year there was no rain but unfortunately the wind was up and noisy gusts were swirling through the canopy.

The logistics of getting a large crew of volunteers up and ready to participate at 6.15am means that we can’t afford to be flexible with our dates so it is a matter of carry on regardless. This year we had 22 volunteers turn up for the count, with most people pairing up, we were able to cover 12 out of our 16 monitoring stations, as is often the case the 4 stations in the southern section of our count area were left out.

Volunteers did a great job of arriving by 6.15 and by the time instructions were given and stations allocated it…

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