Publication Abstract

Application of GIS to investigate the territorial behaviour of two species of Red Sea butterflyfish

D. Righton and C. Mills

The space use of two coral-feeding Red Sea butterflyfish species (Chaetodon austriacus and C. trifascialis) was studied at three sites in the Gulf of Aqaba to determine the extent of intraspecific territoriality. Individuals or pairs were observed in shallow water (<5m) and their locations recorded on maps of each study reef. The Animal Movement Analysis Extension (AMAE) in ArcView was used to plot territory borders and compute measures of territory size for each species. Chaetodon austricus, a generalist corallivore that exploited evenly distributed food resources, maintained small exclusive pair territories with clearly defined territory boundaries. In contrast, C. trifascialis, a specialist corallivore that exploited patchily distributed food resources, demonstrated considerable variation in territorial behaviour that ranged from the defence of small exclusive solitary territories, to the shared use of a large home range. Comparisons of territory area estimates showed that 95% kernel probability density function territory boundaries matched intuitive territory boundaries and, unlike the minimum convex polygon area, did not contain obvious areas that were not used by individuals or pairs. However, most area estimates were strongly correlated and we suggest that using a number of these different measures synoptically can be very useful in describing territorial behaviour between species and studies. For this purpose, GIS is an ideal medium in which to carry out such analyses quickly and easily.

Reference:

D. Righton and C. Mills (2006) Application of GIS to investigate the territorial behaviour of two species of Red Sea butterflyfish. International Journal of Geographic Information Science, 20(2): 215-232.