Thus, five trails were
established in evergreen forest patches previously identified as rufous-necked hornbill habitat
(Poonswad et al., 2009; Jornburom, 2010). Each trail was 9 km long and systematic sampling
points were determined at 200 m intervals (Figure 2), which was appropriate to avoid double
counting birds between two points (Buckland, 1993; Sutherland, 1996; Gregory et al.,
2004).Thus, there were 45 points for each trail. The location of each point was marked using
Global Positioning System (GPS).
The