A 25-year study of “forest patches turned into islands by the filling of the Chiew Larn Reservoir in Thailand in 1986 and 1987” found that these islands, which were unpopulated by people, suffered major species extinction. What this tells us about conservation:
Small habitat patches may not be large enough to sustain a viable population. When ranges are compressed, populations face a number of hardships, from increased competition for resources to inbreeding and intrapopulation strife that can raise stress, increase conflict, and lower breeding rates.
This study isn’t just about isolated islands in a remote corner of Thailand. It’s also about the flecks of land we cordon off every time we fell a forest, plow a field, or plat a subdivision. We’re creating small islands of habitat surrounded by seas of human dominance. Certainly some animals and plants can move between those islands, but not all do and not all at rates needed to sustain remnant populations. … If we are to minimizing the impact we have on the environment—whether those be cities, farms, or even oil fields—we can’t just plan the land we’ll occupy, we have to plan the land we won’t.