Biology Reference
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produced by seasonal winds and breeze and different temperatures modify the sonic
environment as well.
Blumenrath and Dabelsteen (
2004
) have studied the influence of foliation in the
acoustic performance of the great tit (
Parus major
), a species that lives in many
types of habitats and with the capacity of individual recognition of acoustic signals
from conspecifics. The males are able to discriminate the distance at which another
male is singing on the basis of song degradation. These authors have investigated
song degradation before and after foliation using recorded song and a playback
technology. The experiments consisted of recording the effect of foliage/no foliage
on isolated songs. In absence of vegetation the same song degradation observed
when there was a dense cover of leaves was obtained by doubling the distance from
the loudspeaker. In conclusion, the presence of foliage limits long-distance com-
munication in this species, with effects on the territorial organization and
maintenance.
Reviews on the acoustic adaptation hypothesis have been proposed by Ey and
Fischer (
2009
) and a meta-analysis was presented by Boncoraglio and Saino
(
2007
), but despite these attempts a clear discriminatory prospect does not emerge
between species, and rules and exceptions persist, diminishing the explicative
capacity of this hypothesis. It seems that this theory does not explain the communi-
cation constraint everywhere. Although the AAH has been tested in 121 species of
Australian birds from 41 families by Blumstein and Turner (
2005
), only a modest
support for the hypothesis was found.
To test the acoustic adaptation hypothesis, frequency range and trill rate of
chipping sparrow (
Spizella passerina
) were investigated in two different habitats
by Brandley and Burns (
2007
) and Burns (
2007
) without finding significant results.
As the authors stated, however, the small sample size, the closeness of sites, and the
minor habitat differences could have altered the results.
Similar conclusions have been drawn on the long-distance alarm call of four
different species of marmots of North America (the yellow-bellied marmot,
Marmota
flaviventris
; the Olympic marmot,
M. olympus
; the hoary marmot,
M. caligata
;and
the woodchuck,
M. monax
),whichfailedtobeprovedaccordingtotheDanieland
Blumstein results (
1998
). The authors suggest that other factors in this specific case
are responsible for the evolution of species-specific marmot alarm calls.
3.4 The Acoustic Niche Hypothesis (ANH)
Ecological theory states that every species has a unique niche in terms of habitat
and resources to reduce competition with other species (Hutchinson
1959
). Ecolog-
ical niche partitioning is primarily fixed in morphology and then genetically in
behavior, but recent experiments have demonstrated that a learning process could
produces separation in some components of the ecological niche. Slagsvold and
Wiebe (
2007
), manipulating the young of the great tit and blue tit by cross-fostering
in the wild, transferring eggs of the blue tit into the nest of the great tit and vice
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