Behaviour 143, 12 (December 2006)
http://www.ingentaconnect.com/content/brill/beh/2006/00000143/00000012
Couldridge, VCK & MJ van Staaden (2006) Female preferences for male calling
songs in the bladder grasshopper Bullacris membracioides. Behaviour 143:
1439-1456.
Baker, MC & DE Gammon (2006) Persistence and change of vocal signals in
natural populations of chickadees: annual sampling of the gargle call over
eight seasons. Behaviour 143: 1473-1509.
Poesel, A & T Dabelsteen (2006) Three vocalization types in the blue tit
Cyanistes caeruleus: a test of the different signal-value hypothesis.
Behaviour 143: 1529-1545.
Nuechterlein, GL & D Buitron (2006) Advertising by western grebes:
bout-length variability and signal confusion in a multiple-use call.
Behaviour 143: 1547-1562.
Abstracts
Couldridge, VCK & MJ van Staaden (2006) Female preferences for male calling
songs in the bladder grasshopper Bullacris membracioides. Behaviour 143:
1439-1456.
Male acoustic signals and the information they convey are often critical
determinants of female mate choice. Bladder grasshoppers are one of numerous
orthopteran taxa utilizing sound as the basis of courtship and ultimately
mating. However, despite the extreme specializations for long-distance
acoustic communication in this family, female mating preferences for male
calls have not been previously investigated. Here we examine female acoustic
responses to playbacks of male calls in Bullacris membracioides. Females
were tested in three separate contexts, viz. response to conspecific calls
of different individuals, response to degraded conspecific calls, and
response to the calls of two heterospecifics. Female response was
significantly correlated with seven of eight measured call features within
B. membracioides, indicating sexual selection to be operating in this
species. Females also responded to conspecific calls with degradation levels
equivalent to a male calling 150 m away, but intensity equivalent to one at
25 m, identifying call amplitude rather than degradation as the factor
limiting female response. However, as response decreased with increasing
call degradation, signal quality remains a factor in female preference.
Calls of the sister taxon B. intermedia were equally attractive to B.
membracioides females as were conspecific calls, while the more distinct
calls of B. serrata were less preferred than those of both B. membracioides
and B. intermedia. This indicates a lack of discriminatory ability against a
similar sounding heterospecific.
Baker, MC & DE Gammon (2006) Persistence and change of vocal signals in
natural populations of chickadees: annual sampling of the gargle call over
eight seasons. Behaviour 143: 1473-1509.
A study of the gargle call, an agonistic call of the black-capped chickadee
Poecile atricapillus, for eight successive fall/winter seasons in three
resident populations in Colorado (USA) revealed the following: (1)
Individuals had repertoires of calls averaging 8.1 distinct types per bird
(range 2-18). (2) Among individuals in a local population many calls shared
some of the component syllables constituting the whole gargle calls; often
the shared syllables occurred in different locations in the sequences of
syllables (syntax) making up the calls. (3) Individuals also shared many of
the same calls (identical or near identical syllable sequences); thus in a
local sample the ensemble of call types in the population (the population
repertoire) could be found by recording less than 10 birds. (4) In each
population, the ensemble of gargle call types found in a given season
consisted of a core group of about 10 kinds of gargle calls that persisted
over all or nearly all the eight seasons of the study, but also the ensemble
included a number of call types that were present for only one or a few
seasons, or that occurred intermittently across time. (5) The great majority
of call types that were lost from a population were explained by the loss of
individual birds (carriers) by emigration or death. (6) The great majority
of call types new in a population in any given season were explained by the
occurrence of a new bird in the sample (local recruitment or immigration).
(7) Both qualitative classification of gargle syllables and whole gargle
calls by the method of visual inspection of sound spectrograms and automated
quantitative analysis of acoustic features of syllables and calls were
carried out in some examples, and these comparisons gave highly concordant
results.
Long-term studies of cultural evolution of non-song calls are infrequent but
important because the sources and strength of social selection on non-song
vocalizations are often likely to differ from those social factors
influencing cultural evolution in territorial songs, the more often studied
kind of bird acoustic signals. As a primary finding of this study we showed,
using fine-grained measurements of acoustic variables, that a population
retains a set of core gargle groups, each group representing a cultural
tradition (behavioral lineage) exhibiting virtually no drift in detailed
structure across eight consecutive seasons. In a small set of samples of
core groups going back to 1988, there also was no evidence of change within
a vocal tradition. These results suggest the hypothesis of strong canalizing
social selection on the acoustic structure of gargles.
Poesel, A & T Dabelsteen (2006) Three vocalization types in the blue tit
Cyanistes caeruleus: a test of the different signal-value hypothesis.
Behaviour 143: 1529-1545.
Many songbird species use a repertoire of different song types in
close-range interactions. In male blue tits, Cyanistes caeruleus, this
includes songs with and without trill as well as scolding-like
vocalizations. We here investigate using playback experiments whether these
vocalization types are used at different stages during aggressive
interactions, which may be reflected in differential responses of receivers.
We predict that territory owning receivers will vary their strength of
response with the vocalization type of a simulated intruder and that an
aggressive territorial response may include song type matching, i.e. the use
of the same vocalization type as the intruder. Supporting the
different-signal value hypothesis, scolding-like playback elicited a
stronger approach response of focal males than playback of songs with or
without trill. There was no difference in song rate nor do songs without
trill elicit a different strength of response than songs with trill. Males
did not differ significantly in the amount of song type matching between the
treatments but males that landed on the loudspeaker with playback of either
songs without trill or scolding-like vocalizations did not match playback
songs at all. This suggests a trade-off between approach and song type
matching where song type matching is superfluous during very close
approaches. Our results may suggest that in the blue tit threat display may
be graded from songs with or without trill to scolding-like vocalizations
and eventual attack of an intruder.
Nuechterlein, GL & D Buitron (2006) Advertising by western grebes:
bout-length variability and signal confusion in a multiple-use call.
Behaviour 143: 1547-1562.
Studies of song variability in birds have contributed greatly to our
understanding of how animals use vocal signals to communicate information
concerning their individual identity, species, sex, and territorial or
pairing status to other members of the population. Most of these studies
have focused on the songs of male passerine songbirds, where learning plays
an important role in the development of song variability. Here we examine
variability within a multi-functional call of a nonpasserine species, the
western grebe (Aechmophorus occidentalis). In this observational study, we
focused on variability in the lengths of consecutive call-bouts given by
individuals within different behavioral contexts. Early in the breeding
season, Advertising appeared to serve as an initial contact between two lone
courting birds, which then approached and eventually engaged one another in
visual displays. After pairing, however, both sexes continued to use
Advertising calls in a variety of contexts that involved mate recognition or
parent-young communication. Cases of signal confusion or misidentification
of pairing status were rare and generally brief, even within the contexts of
a large colony. During the pre-nesting period, unpaired birds usually gave
bouts of 3-5 calls, while paired birds gave 1- or 2-call bouts. During
incubation, birds returning to their nests often Advertised repeatedly to
their mate using 1- or 2-call bouts in nearly equal proportions. Replies by
their mate from the nest were more likely to be 2- or 3-call bouts (74%) and
appeared to guide the returning bird to the nest. Finally, post-nesting
parents calling to their young or mates primarily used 1- or 2-call bouts.
We suggest that bout-length flexibility likely plays an important role in
providing redundancy in a noisy environment and in limiting signal confusion
in this multi-functional call.
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