The salt was not spilled it was in its original container and I know for the fact this was intentional not birds got trapped and died.
salt is usualy used in white magic to stop spirits demons etc getting into a rom or a house usually an unbroken line across the thresh hold and any windows its works best with sea sal as for the dead birds have no idea
It all depends on what the previous owner was doing with the salt and birds. Salt is often used to stop bad spirits getting in, while the birds could be sacrifices. Honestly, It could be anything.
It may have just been some birds that got trapped and died, and salt that somebody spilled and forgot to clean up.
@ libbyjibean wrong, salt isn't just used in white magick, it can be used in ALL magickm and IS used in more than just white. Other than that, not bad.
Salt also has a long history of use in rituals of purification, magical protection, and blessing.
As for birds, what type of birds were they? And it could also be what Renee said. Unless there is evidence without a doubt that the birds were killed somehow, then I'ld say don't read too much into it.