In biology, regular fluctuations in the size of a population, as seen in lemmings, for example. Such cycles are often caused by density-dependent mortality: high mortality due to overcrowding causes a sudden decline in the population, which then gradually builds up again. Population cycles may also result from an interaction between a predator and its prey.
Blue symbolizes hope, the clear sky, and the streams of the south. Yellow stands for the sun and the Sahara Desert. Red represents unity, prosperity, and national sacrifice. Effective date: 6 November 1959.