Magicicada behavior
As in nearly all cicada species, male periodical cicadas produce
"songs" using a pair of tymbals, or ridged membranes, found on the first abdominal segment.
The abdomen of a male cicada is hollow and may act as a resonating chamber; the songs of
individuals are loud, and large choruses can be virtually deafening. Females of most cicada species do not have
sound-producing organs. Both sexes hear the sounds of the males as well as other sounds using
membranous hearing organs called "tympana" found on the underside of the abdomen.
Over the course of an emergence, males congregate in
"choruses" or singing aggregations, usually in high, sunlit branches. Females visit these aggregations
and mate there, so choruses contain large numbers of both sexes.
Males of all Magicicada species (each described individually
in the species section) produce alarm sounds when
handled, calling songs that attract
males and females to the chorus, and one or more courtship calls when approaching and attempting to mate with
females. Five different male acoustic signals have been
described for the -decim and -cassini cognate species.
Samples of most of these sounds are included below.
These species have calling and courting signals that differ in pitch (frequency)
and other characteristics, but the signals have have similar structures, so they can be described
together. The functions of these signals are not entirely
understood, but they have been given names to indicate their suspected function. The acoustical behaviors
of the -decula species have not been
as well characterized.
Female Magicicada
produce timed "wing flick" signals in response to male calls, and the timing of
this signal in relation to the male call is species-specific for species of the same life cycle. The signal consists of a
quick flip of the wings that creates a broad-frequency sound that can vary from a gentle rustle
to a sharp pop. Males are able perceive both the visual and acoustic components of the wing-flick.
A chorusing male perceiving a female signal
increases his number of calls relative to movement distance, increasing the odds
that he will elicit further responses from any nearby female. If the male
receives multiple responses, he ceases sing-fly behavior, begins CI courtship,
and engages in a signaling duet with the wing flicking female, evidently for the
purpose of locating her. Between calls, duetting males often walk towards the
signaling female, and while approaching, begin CII calling. After contacting the
female or while preparing to mount, the male begins CIII calling, which he
continues until he mounts and copulates. Under some circumstances, males engaged
in duets acoustically obscure the downslurs of potential competitors, reducing
the likelihood of a female response and increasing the likelihood that competing
males will continue chorusing, depart and search elsewhere. Although female
wing-flick signaling is known for many Australian and New Zealand cicadas (e.g., Lane
1995), this is the first reported incidence of female
signaling in North American cicadas. For more detail about female signals in
Magicicada, see Cooley and Marshall 2001.
Male signals: (for recordings see the Magicicada species section)
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Alarm Sound: A rough buzz that males make when startled or handled; it is similar in pitch to the calling song, but coarser.
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Calling song: Attracts both males and females to the chorus.
Male -decim alternate bouts of calling (usually 1-3 calls) with short flights, while -cassini and -decula
may make just one call between flights. The calls are approximately 1.5 - 3 seconds long in -decim and -cassini,
and they are separated by silent gaps of about 1-2 seconds. The calling song of -decula is much
longer, roughly 10-15 seconds in duration.
-
Court I (CI) Call: This signal is
constructed of a series of phrases very similar to those used in the calling song, but
more often without intervening bouts of flying or walking, and often with the gaps
shortened. Males produce CI, CII, and CIII calls when courting a nearby female.
-
Court II (CII) Call: For -decim and -cassini, the
phrases of this call are similar to those in CI calls. However,
there are no gaps between call phrases, and the phrases may be shortened,
or include an upslur.
Males usually produce the CII call
shortly before attempting to mount a female. The Court II call in -decula, if it
exists as in the other two species, has not been well-characterized.
-
Court III (CIII) Call:
This call consists of a continuous series of short, staccato buzzes, about
4-6 per second, in all three species. Males produce this signal while attempting to mount the female,
stopping the sound only after engaging their genitalia.
Female signals:
Female wing flick signal:
Females produce timed "wing flick" signals in response to male calls.
The timing of this signal in relation to the male call is species-specific.
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