Durio zibethinus flowers are large, pale, strongly scented and open for one night only. Work in Malaysia established that the cave nectar bat Eonycteris spelaea is the principal pollinator, with Cynopterus and other pteropodids also visiting flowers for nectar and pollen and transferring pollen between trees.
The distances matter as much as the visits. Eonycteris commutes tens of kilometres between roost caves and orchards, and its diet through the year depends on mangrove Sonneratia flowers when durian is not blooming. That means durian pollination in a given district can depend on mangrove stands and cave roosts many kilometres away, links that are easy to sever without noticing.
Cynopterus brachyotis contributes differently: it is a heavy consumer and disperser of small-seeded fruit, and it builds tent roosts by chewing palm fronds and fig clusters into shelters. A common overstatement is that bats pollinate durian exclusively; other visitors including some insects and birds occur, but exclusion experiments point to bats as the main contributors to fruit set.