R. Zann and E. Cash (2008): Developmental stress impairs song complexity but
not learning accuracy in non-domesticated zebra finches (Taeniopygia
guttata). Behav. Ecol. Sociobiol. 62(3), 391-400.
Abstract: Food restrictions early in life can have adverse effects on the
development of adult avian song structure. Nutritional deficiencies during
brain development are thought to impair the growth of neural circuits
responsible for learning and production of song in adulthood. Thus, the
quality of song may reflect the quality of the singer due to the costs
associated with neural development early in life. Recent investigations have
focused on domesticated laboratory strains of zebra finches where early
dietary deficiencies have significantly reduced the complexity of song and
its sexual attractiveness. Domesticated zebra finches may be more sensitive
to the early effects of moderate under-nutrition on song complexity than
their non-domesticated counterparts. In an aviary experiment with
non-domesticated zebra finch stock, we found that song complexity when
measured by a linear combination of six variables was reduced in
food-restricted birds, with syllable rate and maximum syllable frequency as
the principal variables affected. The restriction had no effect on learning
accuracy when song phrases of experimental birds were compared to those of
their fathers.This result demonstrates that early nutrition may
differentially affect the development of neural processes that influence
learning accuracy and song complexity. While the finding of negative effects
of dietary restriction on song complexity is robust for zebra finches and is
not an artefact of domestication, it does not explain why some nutritionally
stressed populations of wild zebra finches have more complex songs than
those from other regions of Australia characterised by greater food
availability.
URL: http://www.springerlink.com/content/4vqn27v93p6473kp/
For reprints please contact R. Zann (Email:
Daniel T. Blumstein, Louise Cooley, Jamie Winternitz and Janice C. Daniel
(2008): Do yellow-bellied marmots respond to predator vocalizations? Behav.
Ecol. Sociobiol. 62(3), 457-468.
Abstract: We conducted four experiments to determine whether yellow-bellied
marmots, Marmota flaviventris, discriminate among predator vocalizations,
and if so, whether the recognition mechanism is learned or
experience-independent. First, we broadcast to marmots the social sounds of
coyotes, Canis latrans, wolves, Canis lupus, and golden eagles, Aquila
chrysaetos, as well as conspecific alarm calls. Coyotes and eagles are
extant predators at our study site, while wolves have been absent since the
mid-1930s. In three follow-up experiments, we reversed the eagle call and
presented marmots with forward and reverse calls to control for response to
general properties of call structure rather than those specifically
associated with eagles, we tested for novelty by comparing responses to
familiar and unfamiliar birds, and we tested for the duration of predator
sounds by comparing a wolf howl (that was much longer than the coyote in the
first experiment) with a long coyote howl of equal duration to the original
wolf. Marmots suppressed foraging and increased looking most after
presentation of the conspecific alarm call and least after that of the
coyote in the first experiment, with moderate responses to wolf and eagle
calls. Marmots responded more to the forward eagle call than the reverse
call, a finding consistent with a recognition template. Marmots did not
differentiate vocalizations from the novel and familiar birds, suggesting
that novelty itself did not explain our results. Furthermore, marmots did
not differentiate between a wolf howl and a coyote howl of equal duration,
suggesting that the duration of the vocalizations played a role in the
marmots' response. Our results show that marmots may respond to predators
based solely on acoustic stimuli. The response to currently novel wolf calls
suggests that they have an experience-independent ability to identify
certain predators acoustically. Marmots' response to predator vocalizations
is not unexpected because 25 of 30 species in which acoustic predator
discrimination has been studied have a demonstrated ability to respond
selectively to cues from their predators.
URL: http://www.springerlink.com/content/12422575q1567733/
For reprints please contact Daniel T. Blumstein (Email:
Kind regards
Sonja Amoser
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