Bulbuls are birds of Old world tropics and are so attached with Indonesian folklore for long. An old Indonesian children song tells about the bulbuls singing all day from a Cempaka tree (Michelia champaca), quite accurate in portraying the behavior. Bulbuls and their songs are so popular and so connected to each other and have made them popular cage birds. One of the bulbuls, the straw-headed bulbul (Pycnonotus zeylanicus) is believed to be locally extinct in most forests in Sumatra.
Last week, I spent a week in the last remained lowland forest in Sumatra, in Way Canguk research station. Having a walk between the post-burned area and the forest just made me think about these bulbuls. Bulbuls or Pycnonotidae are medium-sized Passerine birds. If you walk across the town, then to secondary forests, and to primary forest, you would see different sets of bulbuls. Sooty-headed bulbul (Pycnonotus aurigaster) is the most common birds of urban areas. Moving towards rural areas, the Yellow-vented (Pycnonotus goiavier) joins the Sooty-headed. In Sumatra, at least in the area I just visited, the post-burned area with more open habitat provides a good foraging site for the Spectacled (P. erythropthalmos), Cream-vented (P. simplex), and Black-crested bulbul (P. melanicterus). And another assemblage of bulbuls is a lot easier to find in the primary forest such as the Puff-backed (P. eutilotus) and the Grey-cheeked (Alophoixus bres).
The post-burned area in Way Canguk of the Bukit Barisan Selatan National Park is the 165 ha area suffered from 1997 forest fire. At this time of the year, Bridelia monoica, the trees of Phyllanthaceae family, are fruiting in the post-burned area. In open area, this tree is growing faster than in shaded area and arranged the middle story of the habitat. The small fruits are favorite food for the three bulbuls of the post-burned area. The Spectacled bulbuls are the most abundant and sometimes fly in flock. They seem unconcerned to human presence. The Cream-vented bulbuls are sometimes joined this flock. The Black-crested is usually in pairs and rather cautious to human. All of them may still visit the primary forest but the fact that they mark the post-burned area (possibly indicator to the area) is to ensure the natural process of forest succession.
Bulbuls can be boring and fascinating at the same time. The brown and dull color of most species is uninteresting but the songs are always captivating. Yes, they do sing….