Indirect evidence that frugivorous birds track fluctuating fruit resources among rainforest patches in the Northern Territory, Australia

Abstract

Abstract Rainforests are naturally fragmented in the Northern Territory of Australia. A census of fruit and frugivorous bird abundance was taken monthly in 10 rainforest patches for 1 year and quarterly for a second year to investigate spatial and temporal patterns among the patches. Fruit abundance showed a marked annual cycle, with a peak around December in the wet season. Four of six bird species showed a significant seasonal fluctuation in abundance, and for three of them, these patterns were different among rainforest types. Three species also showed a significant tendency to be most abundant in the rainforest type with the most fruit in any month. We interpret these results as evidence that birds track fruit resources among rainforest patches of different types. The abundance of two of the species (figbird and pied imperial‐pigeon) was highly variable and did not reveal significantly different temporal trends among rainforest types. These species are probably even more mobile than the other species, although the data in the present study cannot be used to test this theory. The conservation of frugivorous birds and of the plants whose seeds they disperse will require the protection of networks of rainforest patches.