Comparative dynamics of small mammal populations in treefall gaps and surrounding understorey within Amazonian rainforest

Harald Beck, Michael Gaines, James E. Hines, James D. Nichols

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Variation in food resource availability can have profound effects on habitat selection and dynamics of populations. Previous studies reported higher food resource availability and fruit removal in treefall gaps than in the understorey. Therefore, gaps have been considered "keystone habitat" for Neotropical frugivore birds. Here we test if this prediction would also hold for terrestrial small mammals. In the Amazon, we quantified food resource availability in eleven treefall gaps and paired understorey habitats and used feeding experiments to test if two common terrestrial rodents (Oryzomys megacephalus and Proechimys spp.) would perceive differences between habitats. We live-trapped small mammals in eleven gaps and understorey sites for two years, and compared abundance, fitness components (survival and per capita recruitment) and dispersal of these two rodent species across gaps and understorey and seasons (rainy and dry). Our data indicated no differences in resource availability and consumption rate between habitats. Treefall gaps may represent a sink habitat for Oryzomys where individuals had lower fitness, apparently because of habitat-specific ant predation on early life stages, than in the understorey, the source habitat. Conversely, gaps may be source habitat for Proechimys where individuals had higher fitness, than in the understorey, the sink habitat. Our results suggest the presence of source-sink dynamics in a tropical gap-understorey landscape, where two rodent species perceive habitats differently. This may be a mechanism for their coexistence in a heterogeneous and species-diverse system.

Original languageEnglish
Pages (from-to)27-38
Number of pages12
JournalOikos
Volume106
Issue number1
DOIs
StatePublished - Jul 1 2004

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treefall
small mammal
small mammals
rainforest
understory
rain forests
habitat
habitats
resource availability
Proechimys
Oryzomys
rodent
fitness
rodents
food
source-sink dynamics
frugivores
habitat preferences
habitat selection
coexistence

ASJC Scopus subject areas

  • Ecology

Cite this

Comparative dynamics of small mammal populations in treefall gaps and surrounding understorey within Amazonian rainforest. / Beck, Harald; Gaines, Michael; Hines, James E.; Nichols, James D.

In: Oikos, Vol. 106, No. 1, 01.07.2004, p. 27-38.

Research output: Contribution to journalArticle

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