Small vertebrate assessments were conducted in Pahang’s three forest reserves: Tanum, Sungai Yu and Ulu Jelai. The Central Forest Spine (CFS) initiative has identified these forest reserves as CFSI PL1. The assessments were carried out from July until August 2019. This study aims to determine species diversity and update the checklist of small vertebrates in the forest reserves. A 1ha plot was established in each forest reserve for this study. Traps were used to capture and document these vertebrates, including 100 collapsible cage traps, three harp traps, 10 mist nets, and 25 pitfall traps deployed at each sampling site. In addition, the surveys also carried out active searches for herpetofauna and direct observations. Overall, this study recorded 102 species from 35 families of small vertebrates. Of these, small mammals (26 spp. from eight families), birds (56 spp. from 17 families) and herpetofauna (20 spp. from 10 families) were recorded during this study. Tanum FR recorded the highest species diversity of small mammals (H’ value=2.745). Ulu Jelai FR has the highest diversity of birds (H’ value=3.366), and Sungai Yu FR has the highest diversity of herpetofauna (H’ value=2.313). Eleven small mammal species are recorded as new distributional records for the forest reserves. As for birds, this study contributes 25 additional species to the previous checklist of birds in PL1. Compilation of the studies also recorded 22 threatened species of vertebrates in PL1. This information is expected to assist the stakeholders in developing a management plan for the forest mosaics in the corridor to serve as an important habitat for small vertebrates continuously.