Condor, Volume 108(2), May 2006
THE DUET CODE OF THE FEMALE BLACK-BELLIED WREN
Logue, David M.
SINGING OF HERMIT WARBLERS: DIALECTS OF TYPE I SONGS
Janes, Stewart W.; Ryker, Lee
Abstracts:
THE DUET CODE OF THE FEMALE BLACK-BELLIED WREN
Logue, David M.
In many duet-singing songbirds, paired birds combine their song types
nonrandomly to form duet songs. Several different behavioral
mechanisms could generate nonrandom song type associations in duets. I
tested female Black-bellied Wrens (Thryothorus fasciatoventris) for
one such mechanism: adherence to a set of rules linking female
response songs to male stimulus songs. I call this set of rules a
"duet code." Duets of free-living Black-bellied Wrens were recorded
in 2001 and 2002. In 2003 I returned to the same territories and
played the male song types from the recorded duets. Females answered
male song stimuli as if duetting with the playback speaker. Although
the known repertoires of females averaged 8.4 song types, each female
sang only a single song type in response to each male song
type. Random answering could not account for this pattern, supporting
the hypothesis that females abide by duet codes. Females that were
still paired with their mates from 2001-2002 answered 100% of their
mate's songs with the same song types they had used previously,
demonstrating that codes are stable over time. In contrast, females
that were new to a territory answered an average of only 18% of their
mate's song types with the same song type as the previous female,
indicating that duet codes are individually distinctive. Duet
participation by female Black-bellied Wrens represents a special kind
of animal communication, in which discrete vocal signals consistently
elicit discrete vocal responses according to an individually
distinctive set of rules.
SINGING OF HERMIT WARBLERS: DIALECTS OF TYPE I SONGS
Janes, Stewart W.; Ryker, Lee
Hermit Warblers (Dendroica occidentalis) sing distinct dialects of
type I songs, the most common song before pairing. Eight dialects were
identified and described in a 22 900 km2 area in southwestern Oregon
and northern California. The dialects were well defined geographically
with contact areas between dialects seldom extending more than 6
km. Gaps in forested habitat of >= 10 km separated several dialects,
but within forested areas dialect boundaries did not conform to
obvious habitat, elevation, or geographic boundaries. Few songs
containing syllables or phrases from more than one dialect were
identified, and birds incorporating elements from two different
dialects inhabited areas close to the common boundary between the
two. Multivariate analysis showed that birds in neighboring areas had
dialects most similar in structure, but a more complex history of
dialect development or origin is suggested in other areas.
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