Wearing shorts for birdwatching in the tropical forest is not advised because in some areas, there are lots of insects and thorny plants. Light cotton long-sleeved shirt and trouser are recommended for most areas during day time but some areas in the mountains during early mornings and evenings, can be cooler. In the early mornings and evenings of Decemebr-January in the mountains of the North the weather can be very cold so sweater or jumper is needed.
Solid walking shoes are necessary as well as leech-proof socks which may needed in some areas, particularly during the rainy season. Apart from a hat, a folded umbrella (dull colour) can be very useful either to protect you from bright sunshine or from rain. Insect repellent and torch are also advised.