Ammonia has only one nitrogen per molecule, but it is quite toxic. It requires a great deal of water to be flushed out of the body.
Reptiles including birds go one step further, packaging their nitrogenous waste as uric acid. That white stuff you see from a bird or a snake it has less water in the poop.
Birds have uric acid in their nirtogenous waste and humans do not.
Because they excrete different things. While the urinary system removes nitrogen waste from the blood, the digestive system removes food waste that hasn't been absorbed.
urea
their waste
Urea
Nitrogen can be broken down my plants and the soil and from animal waste
Mostly depends on the difference in foods eaten, and in case of birds, that their "plumbing" is quite different.
Ammonia
yes
It is just the way that birds evolved. Birds do not have a separate opening for the urinary tract so both uric acid and feces come out of the same opening. The uric acid is excreted as nitrogen waste.
Birds will either drop whatever they are carrying or their body waste.
through urine
They have uric acid