The Beau Geste hypothesis in animal behaviour is the hypothesis that tries to explain why some avian species have such elaborate song repertoires for the purpose of territorial defence. The hypothesis takes its name from the 1924 book Beau Geste and was coined by John Krebs in 1977. [1]
The Beau Geste hypothesis which was coined by Krebs in 1977 to explain why various avian species have such large song repertories. [1] 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. [2]
The name of the hypothesis comes from the book which was originally published in 1924 "Beau Geste". [3] 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.[ citation needed ]
There has been mention of this hypothesis in places such as research into amphibian vocalizations in the Boophis madagascariensis , an endemic species of tree frog found in Madagascar, [4] 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. [4]
The Beau Geste hypothesis has also been found to explain vocalizations within some cricket species such as the bush cricket, where males use a wide variety of songs to access the amount of competition which is in a given area. [5] 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. [5]
Sexual selection is a mechanism of evolution in which members of one biological sex choose mates of the other sex to mate with, and compete with members of the same sex for access to members of the opposite sex. These two forms of selection mean that some individuals have greater reproductive success than others within a population, for example because they are more attractive or prefer more attractive partners to produce offspring. Successful males benefit from frequent mating and monopolizing access to one or more fertile females. Females can maximise the return on the energy they invest in reproduction by selecting and mating with the best males.
A lek is an aggregation of male animals gathered to engage in competitive displays and courtship rituals, known as lekking, to entice visiting females which are surveying prospective partners with which to mate. It can also refer to a space used by displaying males to defend their own share of territory for the breeding season. A lekking species is characterised by male displays, strong female mate choice, and the conferring of indirect benefits to males and reduced costs to females. Although most prevalent among birds such as black grouse, lekking is also found in a wide range of vertebrates including some bony fish, amphibians, reptiles, mammals, and arthropods including crustaceans and insects.
Bird vocalization includes both bird calls and bird songs. In non-technical use, bird songs are the bird sounds that are melodious to the human ear. In ornithology and birding, songs are distinguished by function from calls.
The Mantellidae are an amphibian family of the order Anura, and are endemic to the Indian Ocean islands of Madagascar and Mayotte. At first glance, the diminutive, brightly-coloured mantellas appear visually similar to the Latin American poison dart frogs, such as Dendrobates, Oophaga and Phyllobates, among others.
Animal song is not a well-defined term in scientific literature, and the use of the more broadly defined term vocalizations is in more common use. Song generally consists of several successive vocal sounds incorporating multiple syllables. Some sources distinguish between simpler vocalizations, termed “calls”, reserving the term “song” for more complex productions. Song-like productions have been identified in several groups of animals, including cetaceans, avians (birds), anurans (frogs), and humans. Social transmission of song has been found in groups including birds and cetaceans.
Boophis goudotii is a species of frog in the family Mantellidae. It is endemic to Madagascar where it is widespread on the high plateau of central Madagascar. Records elsewhere are uncertain and many of them represent misidentifications. It is the only Malagasy frog where females are known to be vocal.
Boophis occidentalis is a species of frog in the family Mantellidae. It is endemic to Madagascar. Its natural habitats are subtropical or tropical dry forests, rivers, pastureland, urban areas, and heavily degraded former forest. It is threatened by habitat loss.
A courtship display is a set of display behaviors in which an animal, usually a male, attempts to attract a mate; the mate exercises choice, so sexual selection acts on the display. These behaviors often include ritualized movement ("dances"), vocalizations, mechanical sound production, or displays of beauty, strength, or agonistic ability.
Vocal learning is the ability to modify acoustic and syntactic sounds, acquire new sounds via imitation, and produce vocalizations. "Vocalizations" in this case refers only to sounds generated by the vocal organ as opposed to by the lips, teeth, and tongue, which require substantially less motor control. A rare trait, vocal learning is a critical substrate for spoken language and has only been detected in eight animal groups despite the wide array of vocalizing species; these include humans, bats, cetaceans, pinnipeds, elephants, and three distantly related bird groups including songbirds, parrots, and hummingbirds. Vocal learning is distinct from auditory learning, or the ability to form memories of sounds heard, a relatively common trait which is present in all vertebrates tested. For example, dogs can be trained to understand the word "sit" even though the human word is not in its innate auditory repertoire. However, the dog cannot imitate and produce the word "sit" itself as vocal learners can.
A mating call is the auditory signal used by animals to attract mates. It can occur in males or females, but literature is abundantly favored toward researching mating calls in females. In addition, mating calls are often the subject of mate choice, in which the preferences of one gender for a certain type of mating call can drive sexual selection in a species. This can result in sympatric speciation of some animals, where two species diverge from each other while living in the same environment.
Soundscape ecology is the study of the acoustic relationships between living organisms, human and other, and their environment, whether the organisms are marine or terrestrial. First appearing in the Handbook for Acoustic Ecology edited by Barry Truax, in 1978, the term has occasionally been used, sometimes interchangeably, with the term acoustic ecology. Soundscape ecologists also study the relationships between the three basic sources of sound that comprise the soundscape: those generated by organisms are referred to as the biophony; those from non-biological natural categories are classified as the geophony, and those produced by humans, the anthropophony.
Female copulatory vocalizations, also called female copulation calls or coital vocalizations, are produced by female primates, including human females, and female non-primates. They are not purposeful, but instead are evolutionary and are spontaneously produced by female primates, including women, to encourage her partner to produce good-quality sperm during the mating process. Copulatory vocalizations usually occur during copulation and are hence related to sexual activity. Vocalizations that occur before intercourse, for the purpose of attracting mates, are known as mating calls.
Polygyny is a mating system in which one male lives and mates with multiple females but each female only mates with a single male. Systems where several females mate with several males are defined either as promiscuity or polygynandry. Lek mating is frequently regarded as a form of polygyny, because one male mates with many females, but lek-based mating systems differ in that the male has no attachment to the females with whom he mates, and that mating females lack attachment to one another.
Sexual selection in amphibians involves sexual selection processes in amphibians, including frogs, salamanders and newts. Prolonged breeders, the majority of frog species, have breeding seasons at regular intervals where male-male competition occurs with males arriving at the waters edge first in large number and producing a wide range of vocalizations, with variations in depth of calls the speed of calls and other complex behaviours to attract mates. The fittest males will have the deepest croaks and the best territories, with females making their mate choices at least partly based on the males depth of croaking. This has led to sexual dimorphism, with females being larger than males in 90% of species, males in 10% and males fighting for groups of females.
Beau Geste is a 1924 adventure novel by P. C. Wren.
The anti-exhaustion hypothesis is a possible explanation for the existence of large repertoires and the song switching behaviour exhibited in birds. This hypothesis states that muscle exhaustion occurring due to repeating song bouts can be avoided by switching to a different song in the bird's repertoire. The anti-exhaustion hypothesis therefore predicts that birds with larger repertoires are less susceptible to exhaustion because they can readily change the song that they are producing.
Boophis popi is a nocturnal species of skeleton frog endemic to the forests of Madagascar. It is characterized by its red irises and distinctly elevated reticulations on the dorsum. It is brown and gray, has slender limbs, a pulsating call, and is slightly larger than similar frogs in its genus. The species was described in 2011 and is named after the company "pop-interactive GmbH".
Boophis fayi is a nocturnal species of skeleton frog endemic to the forests and wetlands or Madagascar with unusual greenish eyes. It is considered to be vulnerable by the International Union for Conservation of Nature.
Boophis entingae is a species of skeleton frog endemic to northern Madagascar.
Boophis haingana is an endangered species of skeleton frog endemic to southeastern Madagascar. It is characterized by its advertisement call, which has shorter note durations and faster note repetitions compared to other frogs in its genus. It is pale green in color and translucent at certain parts of the body, such as the dorsal and ventral skin.