Five related causes probably underlie the more rapid fragmentation in MT. First, there is a paved road running through the south part of the sanctuary that provides ready access both for older established villages to get goods out to market and also for new settlers to enter the sanctuary. There are no paved roads through OK. Second, the accessibility of MT has made the area prime growing land for temperate crops, particularly cabbages, which are sent to Bangkok. Large profits can be generated by such cash crops (e.g. see Tungittiplakorn, 1998). In the 1997/1998 field season we saw many new pick-up trucks as the market price for cabbage was high. Fox et al. (1995) also note the huge impact that a new paved road had on opening up villages to markets in northern Thailand. Third, MT has become increasingly settled by the Hmong ethnic group, who are well known for their skill in cash crop cultivation. Large numbers of illegal and poorly paid immigrants from Burma can be witnessed during harvest time carrying the cabbages to the waiting trucks of the Hmong. In contrast, OK is occupied dominantly by the more sedentary and longer established Karen ethnic group, who have shown less interest in clearing the forests they depend on to grow cash crops for distant markets. The only cabbage growers in OK are the Lahu ethnic group. Most of the ongoing fragmentation is from the expansion of their fields. Fourth, human population numbers are also higher in MT than OK, although little is known of growth rates. Fifth, sanctuary authorities have been more vigilant in OK in their efforts to control deforestation and other violations. Such vigilance in MT was arrested when an officer was shot and killed at his guard post. His surviving colleagues have been less vigilant since that time.