Whodunit

The Pied Fantails looked like done with their nest when their young fledged but in less than a month, these birds were seen rebuilding their little neat home again, and I was looking forward to catching sight of a new chick or chicks earlier than I did the last time.

The original nest.

And one parent seen rebuilding the nest some time later.

And then horrors!  When I checked again a couple of weeks later, this was all that was left - the little cup nest completely pinched off!
Who done it?