Small rodent fluctuations are mentioned in many textbooks as examples of regular population cycles with constant interval and amplitude. However, recent evidence and analyses have indicated much more complex patterns, with geographic trends in frequency and amplitude of fluctuations and covariation with many interacting community components. These new findings indicate that extrinsic factors are much more important for the generation of regular rodent cycles than was earlier believed, and that regular cycles represent only a minority of the dynamic patterns found in rodents. Copyright © 1988. Published by Elsevier Ltd.