Citizen science is an important approach to monitoring for biodiversity conservation because it allows for data acquisition or analysis on a scale that is not possible for researchers alone. In citizen science projects, the use of online training is increasing to improve such skills. However, the effectiveness of quiz-style online training, assumed to be efficient to enhance participants’ skills, has not been evaluated adequately on species identification for citizen science biodiversity monitoring projects. Memory mechanisms in adaptive learning were hypothesized to guide the development of quiz-based online training tools for learning birdsong identification and for improving interest in birds and natural environments. To examine the hypothesis, we developed a quiz-style online training tool called TORI-TORE. We experimentally applied TORI-TORE in Fukushima, Japan, and examined its effectiveness for bird identification training using test scores and questionnaires to determine participants’ attitudes in a randomized control trial. We obtained the following key results: (1) TORI-TORE had positive effects on test scores and trainees’ attitudes toward birds. (2) Adaptive training, in which questions focused preferentially on unmastered bird species based on the answer history of individual trainees inspired by adaptive learning, unexpectedly led to lower scores and satisfaction in TORI-TORE. (3) Focusing on species that are relatively easy to remember, short lag times between training and testing, and long question intervals positively affected scores. While there is room for improvement, we expect TORI-TORE to contribute to online capacity building and to increase interest in natural environments.