Avian detectability and community structure in a Bornean rainforest canopy: Comparing simultaneous ground- and canopy-based surveys

Background/Question/Methods

The rainforests of Borneo are home to a remarkable array of plant and animal species.  This diverse and charismatic avifauna is still poorly understood, and canopy-dwelling birds are particularly understudied.  We conducted simultaneous canopy and ground-based surveys of the avifauna in lowland rainforest sites in Sarawak, East Malaysia (Borneo).  Our aims were: (1) to determine how detectable canopy species were from the ground and vice versa, (2) to assess the connectivity of bird communities of the canopy, sub-canopy, and understory, and (3) assess the role of canopy height in bird detectability and community structure.  Surveys were conducted in lowland rainforest with canopy heights ranging from 20 to 40 meters.  At each survey point, a ground survey was conducted simultaneously with a canopy survey.  The canopy was accessed using tree-climbing methods (single rope method).  Observers communicated via radio to time the surveys, which consisted of simultaneous 3-minute point counts and 10-minute acoustic recordings. 

Results/Conclusions

We found significant differences in the birds that were detected from the canopy versus the ground, with more species detected from the canopy.  Not only were canopy-dwelling species more frequently detected in canopy surveys, but ground-dwelling and mid-story species were more often detected in canopy surveys compared to ground surveys.  These results suggest that canopy surveys are important in gaining a thorough inventory of bird communities in lowland rainforest.