Problem...

1)We have a SEALED container (weight 1 ton) on a(i don't know the word in english... something to weight objects... a scale?).
 2)Inside we have pigeons (weight 10 kilograms)sitting on the floor
 3)They get scared, and start flying inside the ermetic container without touching any of the walls.
 The total weight of the container stais the same(1 ton and 10 kilos) or drops(1 ton)?

I'd like to see a scale that can handle over a ton of pressure yet still measure the weight with an error margin smaller than 10kg... Also 10kg of pigeons... that's a lot of pigeons :P.