Insect pests are one of the causes of yield reduction in oil palm. Birds from adjacent forest remnants can provide pest control services to address this problem. Insect pest control service by birds is available if the ecosystem is functioning with the presence of certain functional groups of birds. Our study aimed to examine bird functional groups that affect the number of insect pests. We assessed the herbivory rate using bird exclosure treatment. We classified birds according to foraging strategy, foraging strata, diet, and body mass traits. Our results showed that gleaning, sallying, omnivorous, and large body-size birds have a significant negative relationship with herbivory rates. However, there were no significant differences between treatment and control of herbivory rates. Thus, the pest control service by these bird groups is equal to ecosystem disservices from adjacent forest remnants.