What kind of transportation is used during a birding tour in Sri Lanka?

For road travel, cars and vans are most common. Various types of luxury busses also used for group tours. Size of busses and other facilities depend with the numbers of people in the group. Almost all the vehicles used tour-operating companies are air-conditioned.

For safaris in national parks, Jeeps are commonly used. Some are four wheel driven (4x4). Most are Indian made jeeps or double cabs without four wheel driven (4x4). Also, there are double cabs modified with high roofs, as safari vehicles. Easily 6 people can use one of these double cab or a jeep vehicle.

Since this is a very general answer. You definitely need to get clear information about the vehicle, from the tour organizer, before book the tour.