Factors affecting population growth rates of 5 ungulate species in a Mediterranean environment

A fundamental prerequisite for conservation and management of animal populations is to know the mechanisms that drive population fluctuations. Analysis of time series data may play an important role in the detection of such mechanisms. However, long-term time series are rare and ungulate data sets hardly exceed 50 years. In this work we analyse a validated long-term data set of population densities of 5 ungulate species in a Mediterranean environment. The series is almost unique for the Mediterranean area, for both its length and the number of species involved. The data set was obtained from the analysis of hunting records in the Preserve of Castelporziano (Rome). The guild includes two endemic Italian subspecies, the Italian roe deer (Capreolus capreolus italicus) and the Maremma wild boar (Sus scrofa majori), and three introduced species: fallow deer (Dama dama), red deer (Cervus elaphus) and an Asian antelope, the nilgai (Boselaphus tragocamelus). Yearly estimates of densities for the five species were computed for the period 1878-1986. A good agreement between this data set and available counts data (1906-1942) was obtained. An effect of direct density dependence in population regulation was detected for all the species. Similarly, effects of inter-specific competition were also observed for some of the species. The effect of climatic factors, forestry management and harvest policy on the dynamics of populations were also analysed and will be discussed.