The Church Bird of Borneo


Tree sparrows (Passer montanus) would not rank particularly high on my list of the world’s most breathtakingly beautiful species.

They are pretty average looking: chestnut brown, some white and a bit of black. Cute but..well, I guess, a bit boring.

Or are they?

In Europe, these sparrows are shy and don’t hang around near people. But here on Borneo, where they were introduced a few centuries ago, their story is different. Their Indonesian name — burung gereja, or “church bird” — confirms their affinity with buildings where lots of people get together.

They are pretty much everywhere, apart from dense rainforests. But even in those forests they find places to live. Sometimes I drive for hours deep into the forest, not a sparrow in sight, to finally come to a logging camp and see it densely populated by these birds. These birds must fly all over the place, follow roads, follow rivers, until they find what they like best: people and their houses.

In the United Kingdom, tree sparrows are red listed, meaning that their populations are fast declining. I find that interesting. What does Borneo have to offer that the UK has lost? With tree sparrows being gregarious and requiring large numbers of nesting hollows, I guess they like the generally messy Asian towns, with lots of chaotically constructed buildings.

On Borneo, tree sparrows are one of the success stories. Even if all trees will be cut, and all bushes burned, this species will likely still be around. In evolutionary terms, it’s a winner.

“But …”, I hear you think, “they are non-native, introduced, invasive, unwanted; they may drive away species native to Borneo.”

So being an evolutionary winner might still get you labeled a conservation disaster.

It’s all very confusing.

(Image: Tree sparrow. Credit: nutmeg66 through a Creative Commons license.)

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