Bioacoustics Theories - Soundscape Ecology: Principles, Patterns, Methods and Applications - page 58

suggests that loudsong in this family of birds is driven by a set of environmental and
behavioral characteristics.
According to the acoustic adaptation hypothesis antbirds that sing on the ground
produce a higher-pitched song than the species singing in the forest midstory,
confirming that song properties are fixed also by habitat structure. Near ground,
with dense vegetation reduces sounds intensity and reverberation is reduced in a
song of 2-5 kHz.
In conclusion, Seddon ( 2005 ) affirms that “ecological adaptation may indeed
drive signal evolution.”
Summary
The structure and complexity of biophonies are the result of evolutionary pressure.
Four major hypotheses are considered relevant for this process. Physical structure
of the organisms, adaptive mechanisms in sound production and transmission,
reduction of acoustic competition, and behavioral processes are possible integrative
strategies to enhance sonic context.
The morphological adaptation hypothesis (MAH) refers to the role of body size
as a biological constraint of the vocalization organs and their acoustic
performances, confirming an inverse relationship between acoustic frequencies
and body size.
The acoustic adaptation hypothesis (AAH) states that the environment is an
important cause of modification and alteration of acoustic signals. Dominant
frequencies and other long-distance calls are the result of interaction between the
animals and their environment to maximize the efficiency of the emitted sounds.
Frequency and structure of acoustic repertoire are plastic traits that can be modified
according to environmental constraints.
The acoustic niche hypothesis (ANH) states that every species has a unique
acoustic space in which to structure the sonic species-specific signature to reduce
interspecific competition and to optimize intraspecific communication mechanisms.
The species recognition hypothesis (SRH) supposes that species living in sym-
patry try to reduce the risk of utilizing similar sonic traits that could confound
species reproduction and create the risk of hybridization.
This set of hypotheses has epistemic relationships to form a meta-bioacoustic
theory.
References
Blumenrath SH, Dabelsteen T (2004) Degradation of great tit ( Parus major ) song before and after
foliation: implications for vocal communication in a deciduous forest. Behaviour 141:935-958
Blumstein DT, Turner AC (2005) Can the acoustic adaptation hypothesis predict the structure of
Australian birdsong? Acta Ethol 15:35-44
Boeckle M, Preninger D, H¨dl W (2009) Communication in noisy environments. I: Acoustic
signals of Staurois latopalmatus Boulenger 1887. Herpetologica 65(2):154-165