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

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.

Patterns of Seed Dispersal and Dispersal Failure in a Hawaiian Dry Forest Having Only Introduced Birds

“…2003). Frugivores can track changes in availability of important food supplies (Loiselle & Blake 1991, Price 2004), and may focus on species that produce fruit when others are sterile (Howe & Primack 1975). The large fruit crop of Bocconia trees, in particular, which, along with Lantana , peaked during the summer months of May–August, may have been one of the few foods available at a time of year when other fruit resources were relatively scarce (Figs.…”

Using hyperspectral satellite imagery for regional inventories: a test with tropical emergent trees in the Amazon Basin

“…The availability of reliable sources of information‐rich satellite imagery like the Landsat platform has enabled study of diverse topics, such as mapping habitat use by caribou (Bechtel et al 2004), identifying migratory bird habitat (Sader et al 1991), and evaluating effects of logging on tree diversity (Foody & Cutler 2003). We are exploring ways in which these approaches can inform the study of tropical frugivorous animals via characterizing the availability of resources in time and space (Fleming et al 1987; Levey 1988; Loiselle & Blake 1991; Price 2004). To better understand the seasonal movements and habitat needs of these animals, much‐improved knowledge of the distribution and phenology of tropical trees is necessary.…”