The Beau Geste hypothesis in animal behaviour is the hypothesis that tries to explain why some

avian Avian may refer to: *Birds or Aves, winged animals *Avian (given name) (russian: Авиа́н, link=no), a male forename Aviation *Avro Avian, a series of light aircraft made by Avro in the 1920s and 1930s *Avian Limited, a hang glider manufacture ...

species have such elaborate song repertoires for the purpose of

territorial defence Territorial Defense or Territorial Defense Forces may refer to: Active * Territorial Troops Militia, a Cuban paramilitary militia under the command of the MINFAR * Territorial Forces (Finland) * Territorial Troops (Kazakhstan) * Territorial Defe ...

. The hypothesis takes its name from the 1924 book '' Beau Geste'' and was coined by

John Krebs John Richard Krebs, Baron Krebs, Kt FRS (born 11 April 1945) is an English zoologist researching in the field of behavioural ecology of birds. He was the principal of Jesus College, Oxford, from 2005 until 2015."Elliott Coues Award, 1999: Si ...

in 1977.

Background

The Beau Geste hypothesis which was coined by Krebs in 1977 to explain why various avian species have such large song repertories. The hypothesis discusses that avian species utilize such large song repertories for potentially a number of reasons such as for territorial defence and to test the competition within a new habitat. The name of the hypothesis comes from the book which was originally published in 1924 "Beau Geste".Wren, P.C (1924). ''Beau Geste''. The book tells the story of three English brothers which all enlisted in the French Foreign Legion and ended up in a desert battle against a Tuareg army. They were greatly outnumbered, and in order to create the illusion that they had more men than they actually had, they took whatever dead soldiers they could find and propped them up along the walls of the fortress.

Non-avian species

There has been mention of this hypothesis in places such as research into

amphibian Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terres ...

vocalizations in the ''

Boophis madagascariensis ''Boophis madagascariensis'' is a species of frog in the family Mantellidae. It is endemic to Madagascar. Its natural habitats are subtropical or tropical moist lowland forests, subtropical or tropical moist montane forests, rivers, freshwater m ...

'', an endemic species of tree frog found in Madagascar,1Narins 2lewis 3McClelland, 1P.M 2E.R 3B.E (March 2018). "Hyperextended call note repertoire of the endemic Madagascar tree frog Boophis madagascarensis". ''the zoological society of London''. 250: 283–298. where the Beau Geste hypothesis is used to give one explanation of why the species has such a large vocal repertoire. There has been some support for the theory in that the frogs use a wide variety of songs to give the illusion to invading frogs that the territory they are trying to enter is already full of competing frogs. The Beau Geste hypothesis has also been found to explain vocalizations within some

cricket Cricket is a bat-and-ball game played between two teams of eleven players on a field at the centre of which is a pitch with a wicket at each end, each comprising two bails balanced on three stumps. The batting side scores runs by striki ...

species such as the

bush cricket Insects in the family Tettigoniidae are commonly called katydids (especially in North America), or bush crickets. They have previously been known as "long-horned grasshoppers". More than 8,000 species are known. Part of the suborder Ensifer ...

, where males use a wide variety of songs to access the amount of competition which is in a given area. When males are present in an area with a large number of other males their vocal repertories are much smaller than when in an area with only a few males.

References

{{reflist Ethology Bird sonation Biological hypotheses