Population dynamics of arboreal and terrestrial small mammals in a tropical rainforest, Sarawak, Malaysia

Lowland tropical forests of Southeast Asia are characterized by general flowering, i.e. irregular and supra-annual fluctuations in flower and fruit production at the community level. We examined the relationship between general flowering and the population dynamics of arboreal and terrestrial small mammals using live-trapping data obtained over 9 years in a lowland tropical forest, Sarawak, Malaysia. The abundance of arboreal and terrestrial small mammals, immature Maxomys rajah (the most commonly caught terrestrial rat) and adult Callosciurus prevostii (a relatively large species and the most commonly caught arboreal squirrel) were significantly negatively correlated with the percentage of fruiting trees with and/or without a one- to two-month lag. The abundance of terrestrial small mammals and immature M. rajah were significantly positively correlated with the percentage of fruiting trees six and five months earlier, respectively. These results indicate that a time lag occurred between fruit production and increases in small mammal populations. Differences in the age classes between the two most commonly caught species during population growth suggest that population increases associated with general flowering were caused by both the recruitment of young individuals of small mammals with relatively low dispersal ability (M. rajah) and the immigration of adult individuals with high dispersal ability (C. prevostii).