Strangely quiet.

I have heard about Magpie funerals but had never seen one. I wondered if yesterdays gathering might have been something like that and it seems possible.
They say that when a magpies mate dies or is killed the survivor sends out a call and all the neighbouring magpies come to pay their respects.
This morning only the male is around and you never usually see one without the other.
He is not making his 'tchack tchack' sound, just a series of low whistles.
Something is amiss.
Here's a video link to one such funeral.