Saturday, July 29, 2006

Colour Variation

In an article that appeared in the December 1997 issue of the Sarawak Museum Journal, Isabel Beasley and Thomas Jefferson noted that the colour of Irrawaddy dolphins in the Mahakam River in Kalimantan (Indonesia) was different from the colour of those found in north Borneo.

“The possibility of multiple stocks of Irrawaddy dolphins in Borneo seems high. Interestingly, Irrawaddy dolphins from the Mahakam River area appear to be very light, almost white in colour, while those observed along the north coast of Borneo have been consistently dark grey.”

The authors had conducted marine mammal surveys in Sabah and Sarawak, where the focused on rivers around Kuching. Whilst most of the dolphins sighted at Santubong, Salak and Buntal are dark grey, not all of them are. Groups of light grey dolphins are frequently sighted. It is not uncommon to see groups of both dark and light grey coloured Irrawaddy dolphins in the same area on the same day. The above picture was taken yesterday at Santubong where both dark and light grey dolphins were present in the estuary.

In their 1997 article Isabel Beasley and Thomas Jefferson pointed out that there were several areas where long term studies of dolphins in Borneo were feasible. They also highlighted the need to further investigate the conservation status of Irrawaddy dolphins in the Mahakam River. Since the article was published no in-depth long term study of Irrawaddy dolphins has been conducted in Sarawak. However, the Mahakam population in Kalimantan has been the subject of research, much of it done by Dr Danielle Kreb and her colleagues at the Yayasan Conservasi RASI, the Conservation Foundation for Rare Aquatic Species of Indonesia. For more information see the

1 comment:

james said...

Hello, I was just going to let you know know that the dredgers operate in the day time on the sea ward side of the park.

Have you used google earth to see the activity in the park itself!

At night time the logging boats come out too, including last saturday night. I'm sure the timber comes from elsewhere!

excuse my not so good english.