Lyrebirds are losing their voices due to continued habitat loss
A new study led by Western Sydney University has found that Albert's lyrebirds are negatively impacted by continued habitat loss, with variation in song diversity indicating declining population health and the need for conservation action.
The study, titled "Depleted cultural richness of an avian vocal mimic in fragmented habitat," published in Diversity and Distributions reveals that Albert's lyrebirds living within fragmented areas have smaller repertoire sizes, mimicking fewer model species and fewer vocalization types.
All lyrebirds mimicked species that are broadly found across the study area, and so repertoire sizes are not restricted by the availability of model species.
Lead researcher Ph.D. student Fiona Backhouse, from Western Sydney University's Hawkesbury Institute for the Environment, explained that the findings suggest that the composition of mimetic repertoires is likely learnt from listening to other lyrebirds, as opposed to learning directly from other model species.
"The smaller repertoire sizes in fragmented areas suggest that there are fewer and more isolated individuals in these areas. The reduced cultural diversity in fragmented, isolated areas could indicate that the health of the local lyrebird populations is under threat," said Ms Backhouse.
"It was surprising that these lyrebirds appeared to be partially compensating for smaller repertoires by mimicking additional sounds from the fewer species within their repertoire."
The findings suggest it is advantageous for male Albert's lyrebirds to have a large mimetic repertoire, likely helping them to attract a mate, and as such they are accounting for the loss of songs in their repertoire by mimicking additional sounds from the species they already mimic.
"Albert's lyrebirds are more restricted in the species they learn to mimic, than in the sounds they learn to mimic. This means that they recognize which sounds come from which species, and that there are 'favorite' or 'socially acceptable' species to mimic in each population," said Ms Backhouse.
The destruction of habitats leading to small, unconnected areas is particularly detrimental to these large, solitary birds. As lyrebirds are poor flyers and unable to travel large distances, substantial areas of intact habitat and good habitat connectivity are important for movement and cultural exchange between populations.
The Albert's lyrebird is only found in a small region of subtropical rainforest in the mountainous areas of Bundjalung Country, on the border between New South Wales and Queensland. Due to their restricted habitat requirements, they are almost entirely limited to rainforest and wet forest and are only rarely found in surrounding drier woodland.
The negative effect of habitat fragmentation on vocal cultures is likely to be widespread across other species with vocal learning abilities, especially those species with poor dispersal capabilities.
Continued habitat loss, particularly for populations already impacted, could mean further loss of cultural diversity. If cultures become too depleted, males will no longer be attractive to potential mates, or mimetic repertoires may no longer be an honest signal of male quality. This could lead to even smaller populations and an even greater loss of culture.
Recommendations to combat the ongoing impact of habitat fragmentation include increasing habitat quality and connectivity by reforesting marginal areas as well as combatting climate change.
This would reduce the risks of a warming and drying climate, that leads to an increased fire frequency, in the fragile habitats that Albert's lyrebirds require.
More information: Fiona Backhouse et al, Depleted cultural richness of an avian vocal mimic in fragmented habitat, Diversity and Distributions (2022). DOI: 10.1111/ddi.13646
Journal information: Diversity and Distributions
Provided by Western Sydney University