Cicada courtship in full swing
The cicada chorus starts around 6:00 in the morning now, and goes until late afternoon, letting up only in the case of rain. Sunnier areas such as forest openings and edges are definitely more attractive to the courting cicadas.
Further online research has revealed that Brood XIV, like most other 17-year cicada broods, includes three different species, of which we have at least two. In the above video, which I shot this morning at the Far Field and the top of First Field, the first-featured species is Magicicada cassini — the one with the more metallic call. My camera unfortunately wasn’t really up to the task of capturing them in flight; they were extremely active in the small locust trees. A box turtle behind the spruce grove at the top of First Field seemed slightly freaked out, but that’s probably my own projection. In reality, she was probably thinking slow turtle thoughts about where to find her next meal.
The final portion of the video shows Magicicada septendecim, which makes the weirder and more musical of the two calls we’ve been hearing. I was surprised by the low volume of its call at close range, but probably it was just getting warmed up. Notice how the abdomen moves as it “sings.” Here’s a description of what’s involved from the University of Michigan Museum of Zoology’s Periodical Cicada Page, the source of most of my information in this post:
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.
As a follow-up to the previous post, my mother emailed a cicada expert at the University of Connecticut named Dave Marshall for more information about the mud turrets she collected. He replied,
No one knows for sure why the cicadas build the turrets when they do. Most of the time they do not, and yet sometimes a whole area will have them built way up several inches. Theories ranges from differences in soil moisture/recent rainfall (nymphs somehow reducing the risk of drowning) to artifacts of differential exposure to light. People were writing about this 100 years ago in USDA pubs, and we have hardly learned any more since then!