Journal of Tropical Ecology



Rainfall but not selective logging affect changes in abundance of a tropical forest butterfly in Sabah, Borneo


J. K. Hill  a1 c1, K. C. Hamer  a2, M. M. Dawood a3, J. Tangah a4 and V. K. Chey a4
a1 Department of Biology, PO Box 373, University of York, York YO10 5YW, UK
a2 Centre for Tropical Ecology, Department of Biological Sciences, University of Durham, Durham DH1 3LE, UK
a3 Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah, PO Box 2073, 88999 Kota Kinabalu, Sabah, Malaysia
a4 Forestry Research Centre, PO Box 1407, 90715 Sandakan, Sabah, Malaysia

Abstract

We investigated the effects of rainfall on the distribution and abundance of the satyrine butterfly Ragadia makuta in selectively logged and unlogged forest on Borneo. In 1997-98, there was a severe El Niño-Southern Oscillation (ENSO) drought, and annual surveys over a 4-y period showed that abundance of R. makuta was greatly reduced during the drought, but that populations quickly recovered after it. Monthly surveys over a 12-mo period of typical rainfall showed that high rainfall in the month preceding surveys significantly reduced butterfly abundance. Butterfly abundance and distribution did not differ between selectively logged and unlogged areas in either monthly or annual surveys and there was no difference between selectively logged and unlogged areas in the pattern of post-drought recovery. These results indicate that the abundance of R. makuta was significantly reduced both after high rainfall and during severe drought, but that these impacts were short-lived and were not affected by habitat disturbance. ENSO droughts on Borneo naturally often lead to widespread forest fires and thus impacts of ENSO events for butterflies are more likely to be due to indirect effects of habitat loss, rather than direct effects of drought on butterfly population dynamics.

(Accepted December 16 2001)


Key Words: climate change; drought; ENSO; habitat disturbance; Lepidoptera; Ragadia makuta; Satyrinae.

Correspondence:
c1 Corresponding author. Email: jkh6@york.ac.uk