High density of bird and pest species in urban habitats and the role of predator abundance

Abstract

A low abundance of predators has been considered an important factor influencing a number of ecological phenomena in urban environments including, in particular, the high population density of some bird and pest species. A low abundance of predators in urban parks also supports the habitat island approach to natural areas in cities since reduced numbers of predators are usually found on islands. Few studies have simultaneously investigated the abundance of birds and their predators in an urban context. The results of this study confirm that the densities of pests (i.e., Feral Pigeons, Starlings, rats, Western House Mice) and most bird species are higher in open-land habitats of urban parks and agricultural urban parks than in open-land habitats in the nearby countryside. Additionally the density of predators (i.e., Kestrels, nocturnal raptors, crows, rats, foxes, cats and dogs) was higher in urban parks. The hypothesis that one of the main causes of some urban ecological phenomena is the scarce predator abundance has to be investigated.