This is by no means a bird confined to MacRitchie, or indeed to Singapore’s forests – the exact opposite. Perhaps one of the most common species in Singapore, the yellow-vented bulbul is a sign of what MacRitchie could become if the Cross-Island Line goes through.
The bird thrives in disturbed habitat – parks, secondary forests, even on roadsides. Within MacRitchie, however, it’s scarce, because the habitat is simply too pristine for it. And because it isn’t present, other, forest species – like the olive-winged bulbul – can thrive in its place.
However, if the habitat becomes opportune – i.e., if the habitat becomes degraded enough – it’ll move in. And because it fulfills the same ecological niche as other bulbul species, and because it’s simply better at thriving in disturbed habitat than them, it’s very likely it’ll then push them out. But as there’ll be nowhere for the other bulbuls to go, eventually the species will become locally extinct.
It sounds like a doomsday prophecy, but it is one with a very high potential of happening. You can see it in MacRitchie’s golf course, where I spotted this individual: very few forest species can be seen there, simply by virtue of there being no forest.
What you have to realize, however, is that the yellow-vented bulbuls are not the bad guys here. They’re simply fulfilling Darwinian logic: survival of the fittest. And if we make the habitat such that they’re the fittest – well, then, the rules of evolution triumph, and we lose a precious slice of our biodiversity.