Robin nest 2017 - a dramatic end?

Part of the early morning routine of late has been to 'check the robin chicks'.  They were getting quite big, and looked to be nearing fledging.... However, Saturday morning's camera view looked like this....

Something has moved the camera (08:13, Sat 7 May in the above screenshot).  As the three chicks have grown there has been a bit of camera jostling going on, but these have only been nudges, so a dramatic shift of perspective cant have been due to the chicks or adult birds.  For info, the above view is pointing out of the hole the adults have been feeding the chicks through, with the nest being a 90 degree rotation to the left.... the obvious question is '...are the chicks still there?

All motion is captured for this nest, we can 'rewind' and capture the 'event'.... so here it is:

Some screen captures identify the culprit....

Top: ?black and white hair
Middle: Looks suspiciously like a cat's paw poking through the entrance hole
Bottom: Is that a whisker?

Culprit = Cattus domesticus

So we immediately assumed that our robin chicks had met a furry end, even after my best attempts to cat proof the nest site, however if we go back to the previous evening, there are no chicks... so did the cat find an empty nest site?

Have the chicks flown the nest??

A collective sigh of relief all round as it turns out that the last two Robin chicks fledged at approx 5pm the previous day, so had a narrow escape.

Chick 2 fledges 

Chick 3 gone a few minutes later

The first chick fledged a full 24 hrs before chick 2+3 , however the adults kept up the feeding on the nest until approx 1 hr before the other two fledged.

Interestingly within a few hours of the nest being vacated... we spotted someone else possibly looking for a home.....

Maybe we will get a bumblebee nest after all....