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

Five camps of flying-foxes (Pteropus alecto and P. scapulatus) were monitor ed regularly in the Darwin region between July 1994 and December 1997. For both species there was a relatively consistent annual pattern in the size a nd age-sex structure of camps. P. alecto appeared to be a local migrant, wi th numbers in the north of the study area negatively correlated with number s in the south, but the movement did not involve all animals. Following bir ths 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 c amp size in P. alecto. Sex ratios varied between P. alecto camps, with a hi gher proportion of females being found in larger camps (P < 0.001), while t he 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 numb ers of the species were present at other times. When integrated with other published information, the pattern seen in this study supports the view tha t P. scapulatus undertakes regular long-range movements and uses habitat in time and space differently from P. alecto.