Communication Theories - Soundscape Ecology: Principles, Patterns, Methods and Applications - page 66

Fig. 4.1 Schematic representation of acoustic interaction between male songbirds. ( a )Two
long-distance interacting males ( left black , grey right ) that have established territories. ( b )Short-
distance interactions at the borders between two males with established territories. ( c ) Short-distance
interactions between a resident male and an intruder coming from a nearby territory. ( d )Short-
distance noninteracting males (a male of an established territory and a nonterritorial stranger).
( e ) Long-distance noninteracting males (a territorial male and a far stranger that has not yet
established a territory) (Modified with permission from Naguib 2005 )
Environmental heterogeneity is a relevant component for animals, and to acquire
information seems the best strategy to reduce the associated uncertainty and to
make the right choices (Emmering and Schmidt 2011 ). In particular, birds use a
multitude of information sources for the different vital functions in their selected
habitat. The biosemiotic mechanism of the eco-field (see Chap. 1 ) is the basis for
tracking resources. For instance, in a closely forested habitat the safety eco-field
(where the focal resource to be located is represented by the safety from predators)
in a dynamic system where animals are in continuous movement is principally
represented by the spatial distribution of acoustic cues that can indicate the pres-
ence or absence of a predator. Thus, a species is able to recognize the signals that
are emitted by a predator during its activity or the alarm calls of potential prey that
first reveal the threat. Experiments conducted by Emmering and Schmidt ( 2011 )on
the ovenbird ( Seiurus aurocapilla ) and the veery ( Catharus fuscescens ), two
ground-nesting passerines that are predated by the eastern chipmunk ( Tamias
striatu s), have demonstrated how species have the capacity of eavesdropping on
the signals of other species, to interpret the signals attributing a specific meaning. In
playback experiments three types of acoustic stimuli were used (chipmunk