Irruptive growth
As Irruption ( Latin for " assault, burglary " ) is referred to in the ecology of a sudden influx of non-resident species, mostly insects and birds in an area. In its area of origin is known, however, as this hike eruption (Latin " outbreak "). The corresponding types are referred to in ornithology as Irruptions - eruption or birds. Cause is usually a gradation in the area of origin, ie, a rapid population increase. Such fluctuation in population dynamics caused about by many successful broods in spring or increased return migration from their wintering grounds in migratory birds. At the same time under supply of food or nesting sites, a population pressure, which led many individuals to Evasion in otherwise shunned regions arises. Often, these birds do not return to their areas of origin and will not be back in the regions home to which they migrate. Instead, there is a Totwandern, that is, the animals come to without returning.