Teachers

Long-term studies that follow every individually marked member of a population over decades are known as long-term marked-population studies. Such research accumulates multi-generational records that integrate phenotypic traits, genetic information, and detailed data on when, how, and how many offspring each individual produces. These datasets allow us to capture ongoing evolution, supported by empirical measurements of fitness. We conduct this type of long-term research on the Ryukyu Scops Owl in the Nansei Islands. Islands are often described as “natural laboratories of evolution” because their ecological simplicity and uniqueness provide ideal settings for studying evolutionary and ecological processes. Through intensive fieldwork on the basic ecology of the Ryukyu Scops Owl, we aim to understand the mechanisms of evolution that apply broadly across organisms. My particular interests include mate choice, population dynamics, and life-history evolution. Each year, we spend as much time as possible on the study island to carry out thorough field surveys. Because understanding the ecological context of the focal species is essential, we also investigate the island’s broader biota across taxonomic groups.

References

Sawada A. (2025). Japanese Weasels Mustela itatsi predate Ryukyu Scops Owls Otus elegans and Ruddy Kingfishers Halcyon coromanda in the Ryukyu Islands. Ornithological Science. 25(1): 97–104.

澤田明 (2024). ダイトウコノハズクの長期研究 標識が教えてくれること. どうぶつと動物園. 74(4): 20–25.

Sawada A., Iwasaki T., Akatani K & Takagi M. (2022). Mate choice for body size leads to size assortative mating in the Ryukyu Scops Owl Otus elegans. Ecology and Evolution. 12(12): e9578.

Sawada A., Iwasaki T., Inoue C., Nakaoka K., Nakanishi T., Sawada J., Aso N., Nagai S., Ono H. & Takagi M. (2021). Missing piece of top predator-based conservation: demographic analysis of an owl population on a remote subtropical island. Population Ecology. 63(3): 204–218.

Sawada A., Ando H. & Takagi M. (2020). Evaluating the existence and benefit of major histocompatibility complex-based mate choice in an isolated owl population. Journal of Evolutionary Biology. 33(6): 762–772.