The Green Internet of Things (IoT) is studied for environmental monitoring, including ecological surveys of wild environments with insufficient electricity, transportation, and communication infrastructure. However, an environmental monitoring method that does not require human intervention is needed because of the inability of replacing batteries during a long-term operation. We focus herein on a carrier pigeon-like sensing system (CPSS) for wildlife monitoring without human intervention. Its agent can be used for any animals and centralize wildlife in the system. This method requires the regular input of animal carriers; hence, the population growth through reproduction may affect the ecosystem during a long-term operation. In particular, a trade-off exists by maintaining system availability and minimizing impact on biodiversity. This study aims to solve the trade-off issue by comparing multiple input scenarios considering intergenerational multi-hop networks. "Intergenerational" is defined when individuals of different release periods encounter each other, and the communication devices wake up to transfer the sensing data of each individual. In the simulation performed herein, the probability of intergenerational multi-hop networks is high, even in the scenario where the number of input animal carriers is high while the number of breeding individuals is suppressed. In this study, we solve the trade-off issue on the animal-to-animal data sharing mechanism, which is important in sustainable wildlife monitoring in terms of the availability of the Green IoT system and impact on biodiversity.