Attack on a Swallow's nest

[(J.D. & H.J. Duigan)]

I am interested to know if anyone had ever observed Blackbirds preying on 
Swallow's nests?
Just before Christmas I heard a great commotion on our deck where a family of 
Swallows were nesting.  I looked out to see three Swallows unsucessfully 
trying to defend their nest from a black coloured bird, the size of either a 
Blackbird or Starling.  I only caught a fleeting glance of the nest robber, so 
I could not positively identify the bird, but it was definitely not a 
Shrikethrush - the usual predator.
Also, several years ago I witnessed a fledgling Swallow being attacked on it's 
first day out of the nest by what looked like a female Blackbird, again I 
can't positively verify the attacker's identify as it all happened so quickly. 
As I have not been able to find any reference to Blackbirds preying on other 
birds nests, I wondered if anyone else had witnessed such an attack.

Helen Duigan,
Emita,
Flinders Island,
Tasmania.