sgeoff

I find these immature birds a bit confusing, especially as the adult tail features are not yet apparent when the feathers are growing.  I assume these two, sitting atop a Causarina on the cable road on Lamma yesterday (Sept 3rd) are immature black drongos, taking into account a combination of body features, behaviour and calls, but can anyone give me a definitive ID and provide a robust diagnostic for the immatures of black and hair-crested?

sgeoff

Thanks for the comments.  I had never noticed that white spot before, and it has proved to be very useful, even if somewhat hard to see in the field.  There have been some great collections of black drongos on the wires in recent days (perhaps getting ready to take off?) with a variety of interesting tail styles.