The Buffer Effect and Productivity in Tit Populations

Certain discussions of the effects of territorial behavior on population density and productivity (e.g., Kluyver and Tinbergen 1953; Tinbergen N., 1957; Wynne-Edwards 1962, p. 149) have concluded that under conditions which are here defined as "level 2," production of young is limited by territorial behavior at some level below the potential maximal production for the population. The present considerations of "optimum mix" and "exchange ratio" suggest an alternative interpretation, namely, that productivity in the Great Tit, at least, is not limited by territorial behavior, but actually might be maximized by it.