Behaviour vol. 146 no. 12 (December 2009)
http://www.ingentaconnect.com/content/brill/beh/2009/00000146/00000012
Abstracts below
Samarra, FIP, K Klappert, H Brumm & PJO Miller (2009) Background noise
constrains communication: acoustic masking of courtship song in the fruit
fly Drosophila montana. Behaviour 146: 1635-1648.
Cardoso, GC & PG Mota (2009) Loudness of syllables is related to syntax and
phonology in the songs of canaries and seedeaters. Behaviour 146: 1649-1663.
Ouattara, K, A Lemasson, K Zuberbuhler (2009) Anti-predator strategies of
free-ranging Campbell's monkeys. Behaviour 146: 1687-1708.
Schel, AM & K Zuberbuhler (2009) Responses to leopards are independent of
experience in Guereza colobus monkeys. Behaviour 146: 1709-1737.
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Cardoso, GC & PG Mota (2009) Loudness of syllables is related to syntax and
phonology in the songs of canaries and seedeaters. Behaviour 146: 1649-1663.
Birdsongs often comprise a variety of different syllables, and some studies
compared sound amplitude among syllables to infer which traits may be more
demanding to sing loudly. We measured sound amplitude of syllables within
songs of 24 species of Serinus, and found that in 19 species some traits
were consistently sung less loudly. This suggests that it is not uncommon
that some syllable traits are more demanding than others to sing loudly.
Which syllable traits were sung softer varied to a certain extent among
species, but some were consistent across the genus: brief syllables and
composite syllables (syllables with several elements) were sung less loudly
in many species. Across species, the more elements composite syllables had,
the stronger its negative effect on loudness, suggesting repeated evolution
of a costly trait. We also found that song syntax was related to aspects of
vocal output. Repeated syntax was related to high sound amplitude, and
non-repeated syntax to high sound to silence ratio. Therefore, syntax may be
subject to indirect selection via its relation with these aspects of vocal
output. These results suggest that the evolution of song phonology and
syntax is influenced by how loudly different species need to sing.
Samarra, FIP; K Klappert, H Brumm & PJO Miller (2009) Background noise
constrains communication: acoustic masking of courtship song in the fruit
fly Drosophila montana. Behaviour 146: 1635-1648.
Drosophila montana males produce a courtship song that is a prerequisite for
mating to occur and which females use to select mates. Here we show that D.
montana female responses to courtship song decreased in the presence of high
levels of noise within the same frequency band as the courtship song, but
not in equivalent noise levels in an adjacent higher frequency band. This
suggests that high noise levels overlapping the frequency band of the song
impair signal detection, but that a mechanism for frequency filtering exists
that reduces the influence of noise in adjacent frequency bands. Although
the acoustic environment of this species in the wild is not known, some
potential sources of noise are discussed. Nevertheless, our findings show
that background noise (biotic or abiotic) within the same frequency band as
the courtship song of D. montana can mask it, suggesting that environmental
noise might affect mate choice and thereby may influence the evolution of
this courtship signalling system.
Ouattara, K, A Lemasson, K Zuberbuhler (2009) Anti-predator strategies of
free-ranging Campbell's monkeys. Behaviour 146: 1687-1708.
Habitat type, predation pressure and reproductive interests are all thought
to determine the anti-predator behaviour of non-primates, but only few
systematic studies exist. Here, we experimentally elicited anti-predator
behaviour in six different groups of forest-living Campbell's monkeys, using
visual and acoustic models of leopards, crowned eagles, and snakes.
Individuals produced a variety of anti-predator behaviours, depending on the
type of predator and whether or not it was visible. Adult males generally
behaved conspicuously, either by attacking eagles or producing threat
behaviours at a distance to leopards. Adult females remained cryptic to
eagles, but joined their male in approaching leopards. To snakes, both males
and females responded strongly to familiar Gaboon vipers, but far less to
unfamiliar black mambas. Finally, if a predator could only be heard, both
males and females produced fewer alarm calls and often changed their
vertical position in the canopy (upwards for leopards; downwards for
eagles), despite all predator vocalisations being presented from the ground.
We concluded that Campbell's monkeys display sex-specific anti-predator
behaviours, which are largely driven by the predators' hunting techniques,
mode of predator detection and the forest habitat structure.
Schel, AM & K Zuberbuhler (2009) Responses to leopards are independent of
experience in Guereza colobus monkeys. Behaviour 146: 1709-1737.
How primates learn to recognise the predatory species from their animate
world is a largely unresolved problem. We conducted predator encounter
experiments with wild Guereza colobus monkeys of the Sonso area of Budongo
Forest, Uganda. The monkeys are hunted by crowned eagles and chimpanzees,
but not leopards, which have been locally extinct for decades. Despite their
unfamiliarity with this predator, monkeys reliably produced appropriate
anti-predator behaviour to leopards, which was indistinguishable from that
of a neighbouring population, where leopards are present. In both
populations, monkeys produced the same vocal responses and predator-specific
alarm calls, although leopard-naïve monkeys were more inclined to approach
when hearing a leopard than monkeys that were familiar with this predator.
Control experiments showed that the monkeys' response pattern was not due to
the effects of unfamiliarity or conspicuousness of the experimental stimuli.
Natural selection appears to have endowed these primates with a cognitive
capacity to recognise direct signs of leopard presence as inherently
dangerous requiring specific anti-predator responses.
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