Flying-foxes (Pteropus alecto and P. scapulatus) in the Darwin region, north Australia: patterns in camp size and structure

Abstract

Five camps of flying-foxes (Pteropus alecto and P. scapulatus) were monitored regularly in the Darwin region between July 1994 and December 1997. For both species there was a relatively consistent annual pattern in the size and age–sex structure of camps. P. alecto appeared to be a local migrant, with numbers in the north of the study area negatively correlated with numbers in the south, but the movement did not involve all animals. Following births in February there was a southward movement of adult P. alecto in March and a return movement northward in September–November. The extent of three vegetation types surrounding camps had a significant effect (P< 0.05) on camp sizein P. alecto. Sex ratios varied between P. alecto camps, with a higher proportion of females being found in larger camps (P< 0.001), while the proportion of juveniles varied over the year (P< 0.05), but not between camps.

Large numbers of P. scapulatus were annual migrants to the southern portion of the study region during July–October 1994–97, but relatively small numbers of the species were present at other times. When integrated with other published information, the pattern seen in this study supports the view that P. scapulatus undertakes regular long-range movements and uses habitat in time and space differently from P. alecto.