THE ROLES OF LONG-TAILED MANAKIN VOCALIZATIONS
IN COOPERATION AND COURTSHIP
iiil ML Trainerfamiliar sound of Monteverde is the court-
ship song of the Long-tailed Manakin, The
call sounds like one bird singing, but it is
actually a well-coordinated duet performed by two
males. This vocal duet is part of an elaborate coop-
erative display and dance (see McDonald, "Coopera-
tion Between Male Long-Tailed Manakins," pp. 204-
205). Because males in a lek mating system do not help
to rear young, females' choice of mate is thought to
be based strictly on the characteristics of males (e.g.,
song) displayed during courtship (Halliday 1978). The
unique social system of the Long-tailed Manakin pro-
vides the opportunity to examine the role of vocal be-
havior in cooperation among males and in the court-
ship of females. My research, in collaboration with
David McDonald, has explored these roles by focusing
on the function of Long-tailed Manakin vocalizations,
the vocal qualities preferred by females during court-
ship, and the development of these preferred qualities.
Long-tailed Manakins have diverse vocal reper-
toires. Males give at least 13 distinct calls, designated
with onomatopoeic names (Trainer and McDonald
1993). Some of the most frequently heard include
"tee-a-moo," which is given by a male to summon his
partner for duet singing. When his partner arrives,
they alternate "wit" calls to synchronize before begin-
ning to sing the "toledo" song in unison. The "toledos"
attract females to the display arena. Once a female ar-
rives, males begin the dance portion of the cooperative
display, which is accompanied by a "nyanyownh" call
with each hop as males leapfrog over one another.
When we played tapes of five common calls, we
found that male manakins responded differently from
territorial birds of other species. They did not behave
aggressively or countervocalize with the tape. Instead,
males generally responded by soliciting interaction
with a cooperative partner. To better understand the
impact of cooperation on communication in Long-
tailed Manakins, we compared the call repertoire sizes
reported in the literature for 13 species of manakins.
Manakin species with joint displays that were competi-
tive rather than cooperative did not have a large vari-
ety of calls. The presence of obligate, joint displays and
the need to mediate long-term cooperative relation-
ships among males may explain why Long-tailed
Manakins have such diverse repertoires.
Our studies also demonstrated the importance of
these partnerships for the courtship success of males.
The "toledo" song must be sung jointly in order to
attract females to the display zone. The duet consists
of two nearly identical vocal components sung almost
in unison (Fig, 6.15). To the human ear, the songs of
some teams sound more coordinated and harmonious
than others. Harmonious duets sound like one bird
singing but have a noticeably fuller sound, easily dis-
tinguished from the rare solo songs. Nonharrnonious
duets sound dissonant and sometimes poorly synchro-
nized, Sonagrams show that in songs that sound har-
monious to human ears, the frequencies of the two
male's song components are well matched. To quan-
tify the acoustic differences in song quality, we mea-
sured the degree of frequency matching with a sound
spectrum analyzer. We found that the degree of fre-
quency matching was correlated with the rate at
which females visited the lek arenas (Trainer and
McDonald 1995; Fig. 6.16). This suggests that females
prefer well-coordinated songs, which could result in
higher mating success for alpha males belonging to
teams with better singing performance.
In male manakins, singing performance improves
with age. In teams including one adult and one im-
mature male, frequency matching increased with the
age of the younger partner. The songs of immature
males became less variable in acoustic structure with
age. The sound frequencies of the contributions of
adult males in well-established teams were betterFigure 6,15. (top) Sonogram of a Long-tailed Manakin
"toledo" song showing the contributions of two male
partners.215 BirdsA