Communication Theories - Soundscape Ecology: Principles, Patterns, Methods and Applications - page 100

Among the environmental factors that can have some influence on acoustic
communication, the steepness of soils may have an important role. Field observa-
tion have confirmed that in birds bodily orientation is a fundamental factor respon-
sible for appropriate transmission of acoustic signals.
Climatic conditions are recognized as important proxies in acoustic communi-
cation, especially in birds and bats. In particular in bats has been recognized the
capacity to change the duration and frequency of the signals according to wet and
dry seasons.
Considering that most of the acoustic repertoires are used by vocalizing animals
for reproductive purposes, the optimization of song performance during the repro-
ductive time confirms this hypothesis, as demonstrated for instance by the grosbeak
( Guiraca caerulea ) song that presents more variants, more versatile arrangement of
elements, and more syntax consistency during the fertile period of the females than
outside this period.
A strict relationship emerges between acoustic cues and antipredatory strategies,
producing changes in behavioral traits and singing performance.
The soft song appears as a secondary acoustic manifestation of some species of
birds to which has been attributed a different significance that ranges from a
courtship to an aggressive behavior. Soft song represents a further categorization
of a great variety of acoustic cues that vocal animals (in this case birds) utilize
during the reproductive time.
Climatic changes have produced dramatic modification in the physiology of
many trees that suffer hydric stress and fires. Insects are important proxies of forest
declines, especially in boreal areas. It has been proven that plants and insects are
deeply connected by an acoustic mechanism. Plants under hydric stress produce a
cavitation sound audible to plant-eating insects that select the more exposed plants
for pest attack.
References
Anderson RC, Nowicki S, Searcy WA (2007) Soft song in song sparrows: response of males and
females to an enigmatic signal. Behav Ecol Sociobiol 61:1267-1274
Ballentine B, Badyaev A, Hill GE (2003) Changes in song complexity correspond to periods of
female fertility in blue grosbeaks ( Guiraca caerulea ). Ethology 109:55-66
Balsby TJS, Dabelsteen T, Pedersen SB (2003) Degradation of whitethroat vocalizations:
implications for song flight and communication network activities. Behaviour 140:695-719
Barbieri M (2003) The organic codes. Cambridge University Press, Cambridge
Bee MA (2007) Sound source segregation in grey treefrogs: spatial release from masking by the
sound of a chorus. Anim Behav 74:549-558
Buchanan KL, Catchpole CK (2000) Song as an indicator of male parental effort in the sedge
warbler. Proc Biol Sci 267(1441):321-326
Byers BE (1996) Messages encoded in the songs of chestnut-sided warblers. Anim Behav
52:691-705