Vocal Mimicry: Selection

The male superb lyrebird (Menura novaehollandiae) uses vocal displays when encountering rival males or before mating. 70% of the superb lyrebirds repertoire consists of imitations from approximately 20 different species of neighbouring birds (Dalziell & Magrath, 2012). As the receivers are either rival males or potential mates, Dalziell & Magrath (2012) strongly suggest that the mimetic vocalizations are a sexually selected trait.

Because of this, large repertoires may be more favourable by selection than mimicry, as a wider variety of songs give the superb lyrebird increased mate choice and territorial defence. However, obtaining a large repertoire would require mimicry as a shortcut (Dalziell & Magrath, 2012).

As I’ve already mentioned in my previous post (Vocal Mimicry: Accuracy vs Versatility) superb lyrebirds are highly accurate mimics. Coleman and colleagues (2007), in their study of satin bowerbirds (Ptilonorhynchus violaceus), suggest that high accuracy is driven by female preferences in complex mating displays. A correlation can be made about mating success and accuracy, as modification of vocal motor patterns, and learning and refinement of displays as a juvenile is required for mimetic accuracy (Coleman et al. 2007).

To date, only two studies have been successfully conducted on the mimetic accuracy of this species, so conclusive information is limited, but not unknown.

Dalziell & Magrath (2012) found that there is strong selection favouring accuracy rather than large repertoires in order for mating success, and that a species can decipher signal structure and contextual learning to distinguish between the model and imitations.

Quality over quantity.

References:

Coleman, S.W., Patricelli, G.L., Coyle, B., Siani, J. & Borgia, G. 2007, "Female preferences drive the evolution of mimetic accuracy in male sexual displays", Biology Letters, vol. 3, no. 5, pp. 463-466.

Dalziell, A.H. & Magrath, R.D. 2012, "Fooling the experts: accurate vocal mimicry in the song of the superb lyrebird, Menura novaehollandiae", Animal Behaviour, vol. 83, no. 6, pp. 1401-1410.

Vocal Mimicry: Accuracy vs Versatility

It’s the age-old question of quality or quantity. Is it more advantageous to have a large repertoire of songs of average quality or a few high quality songs accurate enough to fool even the best receiver? Continuing on from my last post (Vocal Mimicry), I will discuss the accuracy of mimicry versus versatility and having a large portfolio of songs in lyrebirds (Menuridae).

Dalziell & Magrath (2012) measured the superb lyrebirds (Menura novaehollandiae) ability to successfully deceive grey shrike-thrush (Colluricincla harmonica). They did this by using playback experiments of the imitated shrike-thrush song and the actual song, and also by measuring the acoustic properties of the two. 

When the shrike-thrush heard the superb lyrebirds mimetic song, they reacted strongly as though it was their own. However, when the mimetic song was played alongside the actual song, the shrike-thrush still approached the speakers where the audio was playing but were not as convinced (Dalziell & Magrath, 2012).  

Image: The Superb lyrebird (top) known to mimic the songs of the Grey shrike-thrush (bottom) in order to increase availability to resources such as food and mates.

The acoustic properties of the mimetic song were amazingly similar to those of the actual song, where the lyrebird achieved the correct structure and complexity. However the lyrebird failed to display the same repetition of element types within the song, and instead emulated their own natural singing style (Dalziell & Magrath, 2012). 

In my next post I will discuss the selection for accuracy and versatility, and which is favoured more by selection. 

References:

Dalziell, A.H. & Magrath, R.D. 2012, "Fooling the experts: accurate vocal mimicry in the song of the superb lyrebird, Menura novaehollandiae", Animal Behaviour, vol. 83, no. 6, pp. 1401-1410.

 

 Photos:

Grey shrike-thrush. Image by Richard Hall www.richardhallphotography.com

 Accessed:  12th April 2015

Superb lyrebird. Image BrocPhoto www.birdforum.net

Accessed: 12th April 2015

Vocal Mimicry

Most people associate vocal mimicry with parrots, with records dating back to the 1500’s where Henry VIII of England had a Grey parrot (Psittacus erithacus) renowned for mimicking his servants. But did you know bottlenose dolphins (Tursiops truncatus), harbour seals (Phoca vitulina), killer whales (Orcinus orca), orangutans (Pongo spp.) and African savannah elephants (Loxodonta africana) have all been known to display vocal mimicry? (Kelley & Healy 2011)  

A camera shutter, a car alarm and a chainsaw aren’t exactly the noises that come to mind when you think of a songbird. Sadly enough, these are some of the sounds made by one of the most impressive vocal mimics, the lyrebirds (Menuridae).  Watch the video below to see David Attenborough witness the lyrebird in action.

 WATCH: Attenborough: the amazing Lyre Bird sings like a chainsaw

Video: The Superb lyrebird displaying an array of sounds, including bird songs, camera’s, car alarms and chainsaws.

Vocal mimicry requires a mimic (in this case the lyrebird), a model (the sound being mimicked) and the receiver (the unsuspecting individual the mimic is trying to pursue).

Dalziell & Magrath (2012) found that the Superb lyrebird (Menura novaehollandiae) is capable of successfully deceiving other species or conspecifics into believing their sounds are coming from one of their own. The benefits from this sneaky deception include protection from predators, increased resources such as food and shelter, and mating advantages (Dalziell & Magrath 2012).

There’s always a downside though.  The elaborate songs of the lyrebird can often lead to detection from predators, conflicting signal requirements (accurate recognition from the receiver) and costs imposed by the model (the sound being mimicked) (Dalziell & Magrath 2012).

I will continue this topic in my future posts, where I will discuss selection strengths, accuracy and versatility.

REFERENCES:

Dalziell, A.H. & Magrath, R.D. 2012, "Fooling the experts: accurate vocal mimicry in the song of the superb lyrebird, Menura novaehollandiae", Animal Behaviour, vol. 83, no. 6, pp. 1401-1410.

Kelley, L.A. & Healy, S.D. 2011, "Vocal mimicry", Current Biology, vol. 21, no. 1, pp. R9-R10.

VIDEO: BBC Worldwide, 2007. “Bird sounds from the lyre bird – David Attenborough - BBC wildlife”

https://www.youtube.com/watch?v=VjE0Kdfos4Y Accessed 7^th April 2015