Red-whiskered Bulbuls

This species is rarely seen in my backyard, compare to abundant of yellow-vented bulbul.

Red-whiskered Bulbuls inhabit a variety of semi-natural and human-modified landscapes, including open wooded areas, gardens, parks, and even urban environments, rather than dense primary forests. These birds thrive in areas with plenty of fruit-bearing plants, as they feed on fruits, nectar, and insects. (from Ai-Overview)

That match by backyard environment

Only two occasion that I have accouter, perhaps I didn't look hard enough.

Two Yellow-vented Bulbuls and Red-whiskered Bulbul

crested bulbul (Pycnonotus jocosus pattani) 

 

Vented (bottom of the tail) is red in colour same as Red-Vented Bulbul (never seen, not native to Malaysia)

on papaya tree