Two Suspicious Deaths

I was having my post-tennis reward this morning when I was interrupted by my phone. It was my dad's carer:
'Bob, your dad's not feeling well and both the canaries are lying dead in the bottom of the cage'.
Well, long story short, the gas man was called and found nothing untoward, no gas leaks, no carbon monoxide. The doctor was called and found nothing untoward but referred dad to A&E to check for CO in his blood; nothing.

So did they jump or were they pushed?