Sifaka troops (Propithecus verreauxi) at Berenty, Madagascar, seem stable numerically, geographically, and in spacing behavior. Recognizeable individuals preserved their 1963-1964 ranges in 1970, in a classical mosaic of defended territories. Lemur catta had twice as many troops of half the mean size in 1970, and had changed from spatial exclusivity to time-plan spacing, both within and between troops, with intertroop ‘battles’. The change may reflect long-term population effects or seasonal food shortage.