More thorough and ecologically relevant observations of changing conditions are urgently needed as climate change perturbs species and ecosystems. Conventional climate measurements are often constrained by biased sampling, and only tangentially relate to ecosystem responses. Here, we exemplify how animal borne instruments (ABIs), a collection of on-board sensors used in conjunction with animal tracking technologies, might offer a significant improvement. Billions of fine-scale meteorological observations have already been collected by ABIs and over a thousand species have been tracked to date. Tagged animals could fill in important data gaps worldwide and broadly function as active earth observing environmental sentinels.