DEFINITIONS OF TERRITORIALITY USED IN THE STUDY OF VARIATION IN VERTEBRATE SPACING SYSTEMS

Both species and populations within species display variation in spacing patterns, and the number of published reports documenting this variation is increasing rapidly. The potential for instructive comparisons is high, but the comparative approach requires common terminology. Vague or implicit definitions of spacing systems undermine the rigour of comparisons. Papers were reviewed that examined interspecific and intraspecific variation in spacing systems to determine the degree to which definitions currently produce a common terminology. This report describes and classifies the 48 conceptual and operational definitions of territoriality found in the literature. Only 12% of the papers gave an operational definition of territoriality. The single criterion of 'defended area' was used in 50% of the papers, and the other 50% used other definitions which often consisted of multiple criteria. These definitions were variants of three main themes: defended area, exclusive area, and site-specific dominance, and authors used up to three criteria to define territoriality. Conceptual and operational definitions differed because different questions were asked and because of logistical problems, such as collecting the same data on different species or populations. The taxonomic group being studied also seemed to determine which type of definition was chosen. Although defended area was used most often across four classes of vertebrates, researchers studying mammals chose spatial criteria, for example, amount of home range overlap, more often than researchers studying other taxa. Workers pursuing research in this area can enhance their contribution by using clear conceptual and operational definitions of territoriality, making them explicit at the outset.