Resource use among sympatric Callosciurus spp. (Sciuridae) in tropical seasonal forests during the dry season in northeastern Thailand

Southeast Asia contains a diverse array of squirrels, with several species living sympatrically. However, limited data are available on how the squirrels coexist and share resources in the same habitat. Here, we examined resource-use variation between sympatric Callosciurus finlaysonii and C. caniceps in two habitats of northeastern Thailand: dry dipterocarp forest (DDF) and thy evergreen forest (DEF). Both species were bimodally crepuscular and did not differ in daily activity patterns. Callosciurus caniceps was fewer in number than C. finlaysonii in DDF, but they had similar frequencies in DEF. The two species generally consumed different plant species, though some preferred fruits overlapped. Callosciurus finlaysonii from DEF remained higher in the trees than C. caniceps; all nests at elevated locations belonged to C. finlaysonii. When feeding, the preferred height of both species varied depending on food availability. In DEF, C. caniceps dominated C. finlaysonii during interactions. Together, our observations indicate that sympatry is possible because the two species differ in food choice and/or engage in vertical zonation.