Scaling patterns in exotic and native bird species distribution and abundance

Scaling phenomena are at the core of a great variety of ecological processes ranging from individual physiology to population, community and ecosystems, and emerge as the result of the operation of general principles governing their structure and functioning. In this chapter, we assess the generality of scaling relationships in the distribution and abundance of species by comparing invasive exotics and native species recorded in the Breeding Bird Survey within the North American continent. To do this we compare scaling patterns in nine exotic species (the exotic set) and compare them to a set of native species chosen to maximize taxonomic and ecological similarity (the similar set) and to a random set of native species (the random set). For each set of species we assessed the scaling of the spatial characteristics of range occupancy, the intraspecific and interspecific scaling between distribution and abundance and the scaling of the abundance frequency distribution. Our results indicate that exotic and native species show similar scaling patterns in their distribution and abundance, which suggests they are under the influence of similar process thus supporting the generality of these scaling relationships. However, exotic species do differ from natives in a key aspect of their ecology; they are able to reach higher maximum abundances and show a more even abundance-distribution relationship, probably as a result of having broad ecological tolerances, which could be a key to their successful establishment and further spread.