Characterizing common and range expanding species

Climate change and biological invasions have increased the likelihood of the establishment, growth, spread and survival of some species. With the recent and strongly motivated call for balanced consideration of the ecology and conservation of common and rare species, species undergoing range expansion are of particular interest. The notion of essential biodiversity variables has also re-focussed attention on the value of abundance and occupancy observations for assessing conservation values, threats and targets - species rare or common, contracting or expanding. Changes in the distribution and abundance of common and range expanding species deserve further attention, not only to better understand their dynamics, but also as the basis for monitoring range expansions and their consequences. With the aim of characterizing range expansion, here we combine perspectives from typological approaches to studying species conservation status with perspectives from spread ecology and macroecology. Closer examination of the properties and dynamics of common species is important not only because declines in their conservation status are underappreciated, but also because those species becoming more common have significant implications for biodiversity, ecosystems and society.