Study
Increased Reproductive Success at High Densities and Predator Satiation for Periodical Cicadas
Karban, Richard
Ecology, 1982
Cicada densities were manipulated across field plots during an emergence, and survival to reproduction measured, testing whether individual survival improves as local density rises — the prediction of the predator satiation hypothesis.
- Studied in
- Magicicada
- Sample size
- cicada densities manipulated across experimental plots
Individual survival increased markedly with local density. At high densities predators took a smaller proportion of the emergence, and per-capita reproductive success rose. At low densities cicadas were heavily predated.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
Synchronised mass emergence functions as predator satiation: a cohort large enough to exceed local predator appetite ensures most individuals survive to breed.
How NatureHQ reads it
This is the mechanism that makes the whole strategy coherent, and it explains a feature that otherwise looks like a design flaw. Periodical cicadas are slow, edible, defenceless and enormously conspicuous. The answer is that they are not trying to avoid being eaten; they are trying to be eaten as a small fraction of an unmanageable total. Predators cannot build up their numbers in advance because there is nothing to eat for sixteen years, and they cannot eat a fraction of the emergence that matters. Being defenceless in overwhelming numbers is the defence.
- Field manipulations of density are coarse and cannot fully control predator movement between plots.
- One emergence in one region.
- Satiation explains synchrony but does not by itself explain the particular cycle lengths.
Testing whether safety really does come in numbers
Are periodical cicadas safer simply because there are so many of them?
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Published by: Wiley journalsPublished in a Wiley journal.
This reference was resolved automatically against Crossref on 2026-08-11.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-08-11.