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| A female Albert's lyrebird from Mt Tamborine (photo: D. Putland). |
Australia's two lyrebird species (Albert's lyrebird, Menura alberti, and superb lyrebird, M. novaehollandiae) are famous for their complex visual and vocal displays. Male lyrebirds build platforms on the forest floor from which they perform their characteristic displays in which their filamentous tails are fanned and arched over their bodies while they produce their distinctive loud calls. They are consistently rated among the top songsters of the world. Their vocalisations include a large proportion of mimicry of other rainforest animals, and they are also known to copy man-made noises such as cars and chainsaws. These abilities have made the lyrebird an icon of the eastern Australian forests. They have also attracted a share of international fame, such as their starring role in the recent BBC series, The Life of Birds.
All male Albert's lyrebirds within a population produce roughly the same sequence of mimicked sounds in their cyclical display song, but the sequence varies among populations. This type of rigid cyclical song structure is found in only a few other species (eg. village indigobirds and humpback whales). The songs or calls of at least 10 bird species are observed within sequences of mimicry, and in some cases several different songs or calls from the same species are included. These observations have been interpreted as clear evidence of cultural transmission (i.e. that Albert's lyrebirds learn their calls from each other and not from their environment).
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Spectrograms showing the variation in lyrebird advertisement songs between two populations at Gambubal and Mt Warning. |
There have been no detailed quantitative analyses of the variation in song structure among populations of either lyrebird species. It is not known whether the variation in mimicked components among populations reflects the underlying variation in the songs produced by the model species. For example, mimicry of the songs of the satin bowerbird feature prominently in the lyrebird display, and the songs of this model species are known to vary among these populations. Does the lyrebird show similar patterns of variation? It is also unclear whether the entire song is transmitted as a single unit, or if it results from a complex interaction of alternative learning paths (eg. could the sequence be culturally transmitted, but the elements themselves be repeatedly learnt from the model species?).
This research aims to provide the first detailed analysis of the geographic variation in the songs of this species, and to investigate whether the variation in lyrebird song accurately reflects the variation in the songs of the species they copy. It will also involve the use of playback experiments to investigate the role of cultural evolution in shaping lyrebird song. With modern signal editing techniques, it is possible to generate synthesised song sequences suitable for use in playback experiments; for example, the original population's song sequence, a sequence generated by rearranging phrases of mimicry within the cycle (same phrases but in a random order), and a sequence generated using recordings of model species songs from the same area (same order but with different elements).
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| This graph shows how the two species have parallel patterns of song variation among the six sites. The clusters represent songs that are similar in structure. Open shapes represent bowerbird advertisement songs while matching closed shapes represent the lyrebird imitations from the same sites. |
The first results of this project have been published recently in Biology Letters. We have shown that each population of lyrebirds faithfully reproduces the advertisement song of the local satin bowerbirds. This is the first demonstration of parallel song variation, or dialect matching, in species that do not share a tight ecological association (such as brood parasitism). The patterns of variation (illustrated in the graph on the left) suggests that lyrebirds learn this song both by copying directly from the local bowerbirds and also by partly copying off each other (cultural transmission).
Use the controls below to listen to songs from each species from each of the six sites.
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This project has received funding from the University of Queensland, Birds Australia, the Royal Zoological Society of New South Wales, Australian Geographic and the Bird Observers Club of Australia. Special thanks to the Green Mountains Natural History Association and the Queensland Parks and Wildlife Service, especially Ian Bryant (permits), Michael Hall (Springbrook), and Andy and Vanessa Quirk (Green Mountains).
