Monitoring the population of the firefly Pteroptyx tener along the Selangor River, Malaysia for conservation and sustainable ecotourism

Veronica Khoo1, B. Nada & Laurence G. Kirton

Ohba Firefly Institute, 4-1-12-204 Maborikaigan, Yokosuka City 239-0801, Japan.


The Selangor River estuary is well known for its large population of synchronously flashing fireflies, Pteroptyx tener, which congregate on trees (especially Sonneratia caseolaris) growing on the edges of the riverbank. As a result, it has become an ecotourism destination that contributes to the livelihood of the local community. In recent years, villagers and tourists have pointed to a decrease in the numbers of fireflies, an issue further highlighted by the media. Factors that have been suggested as contributing to the decline are river pollution, water extraction upstream, clearing of vegetation and erosion.

However, no quantitative data was available on the status of the firefly population. In response to this, the Forest Research Institute Malaysia began monitoring the firefly population from May 2006 as an integral part of conservation efforts for the firefly. Using digital night photography and image analysis, the techniques for which are described separately in another paper, it was possible to monitor seven sites amounting to a cumulative length of 1.6 km of the riverbank.

Data from May 2006 to April 2009 are presented. An index of abundance of the adult firefly population was obtained, which was compared against environmental parameters such as rainfall, relative humidity, temperature, air quality, water quality and water salinity. The population was observed to peak in the middle of each year and was low towards the end of each year. Annual population cycles appeared to be influenced by rainfall.

Fluctuations in the annual population level were observed over the three and a half year period but it is too early to conclude a specific trend. The importance of on-going, long-term monitoring is discussed. Through the images obtained during monitoring, habitat loss was also detected and highlighted to the State Government, which in turn lead to measures being taken to confer greater protection to the riverside vegetation.

tags: Firefly, Pteroptyx tener, population, monitoring, conservation, Selangor River, Malaysia