Significance of habitat structures as a regulatory mechanism for the breeding density of Carrion Crows (Corvus corone corone)

In four regions of Lower Saxony with a total area of 113 km(2) we examined woods and electricity pylons as habitat structures with respect to their fr equency distribution and suitability as breeding places of carrion crows. W e determined real population densities and calculated a hypothetical breedi ng density in relation to habitat structures in order to test a possible re gulative effect of these structures on regional differences in settlement d ensity of Corvus c. corone. The regional capacities indicated a hypothetica l breeding density 3.2 to 7.6 times higher than was proven in reality, Even in a medium-sized territory of 0.5 km(2) (a value to be found in literatur e) a 1.4 times higher density is still possible. Furthermore, the regional nest distribution established by the index of dispersion was random, but th e habitat structures showed clumping. Neither the habitat structures on the ir own nor in combination with territory size can be regarded as definite m echanisms of regulation in the choice of territory and breeding place and t hence of the distribution and settlement density of Corvus c. corone. The p ossible influence of food supply and non-breeding populations on distributi on patterns and settlement densities is discussed.