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
So, this is an example of the lyrebird’s versatility, not its accuracy? Why do you think the lyrebird has evolved such an extensive repertoire? How does the female lyrebird recognize the male … doesn’t she get confused if he makes several different calls, and she can’t see him? Fascinating.
ReplyDeleteThere may be two theories as to why the lyrebird has evolved an extensive repertoire, the first being the females desire for song complexity. To produce an array of highly complex songs requires developed neural abilities, reflecting the age, condition and overall fitness of the mimic (an important component in mating success). The second theory was proposed by Hindmarsh (1984) in his study of the European starling, (Sturnus vulgaris), stating that a large repertoire may arise from 'learning mistakes'.
ReplyDeleteThe male lyrebird is relatively large in size, measuring approximately 80-100cm in length, and perform elaborately flamboyant displays on platforms made from twigs and earth. These displays along with the mating calls (often lasting 30 minutes) are what attracts the female lyrebirds. And with a tail spanning 55cm consisting of 16 feathers, the males are easily recognizable (Callahan, 2014).
Callahan, A. 2014, "The superb lyrebird: Creature feature", Nature New South Wales, vol. 58, no. 3, pp. 26-27.
Hindmarsh, A.M. 1984, "Vocal Mimicry in Starlings", Behaviour, vol. 90, no. 4, pp. 302-302.
Zann, R. & Dunstan, E. 2008, "Mimetic song in superb lyrebirds: species mimicked and mimetic accuracy in different populations and age classes", Animal Behaviour, vol. 76, no. 3, pp. 1043-1054.