The nest of the swallow bird is made from the solidified saliva of the bird, and this is a very expensive tonic delicacy in South East Asia, as well as other places such as China and Hong Kong. There are some swallow birds at Karimun Island, the some local people use the upper storeys of their houses as a place for the swallows to lay their nests so that these can be harvested and sold. The birds enter the house by a hole in the top floor (see photo) and they always return to the same house every evening. This is a very big business in Karimun Island as well as nearby places such as Bengkalis, Selatpanjang and even on Sumatra.
If you want to have an experience of the rural lifestyle on a tropical Indonesian island, you need to get away from the main town of Tanjung Balai and walk around some of the local kampung areas. Once you are out of Tanjung Balai, it is much safer as the local villagers are friendly. Please visit the VT travelogue of this page for more photographs.
Tanjung Balai is the main town of Karimun Island, and it is one of the busiest town among the Riau Islands. Perhaps this is due to the fact that it is somewhat of a cross-road between Indonesia, Malaysia and Singapore. You can walk around and explore this town on your own or you can take the local transport, which is a van which acts as bus (there is plenty of them on the streets and the price is very cheap, but local language is essential). However, be careful as there are beggars around and pickpockets as well.