They do that because it is a natural instinct. Almost all birds at one time in their life they hit their beak on something.
Because of the nature of a parrot's diet (seeds, fruits and nectar from blossoms), seeds and sticky substances will adhere to the beak. Banging the beak is sometimes the only way these foreign materials can be dislodged.
chiddy bang
Mark Ronson & The Business Intl - Bang Bang Bang
something that caused the big bang is scientifically unknown
It will go 'bang' when it hits something.
Bang for Your Buck - 2009 Austin Green Kitchens 6-1 was released on: USA: June 2011
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There is no commonly recognized term "bang bang army." It may refer to something specific within a local context or a colloquial term unrelated to any established concept.
Lillian 'Lil' woods plays Megsie Green in Nanny Mcphee: The Big Bang
actually the big bang is something I don't believe in I believe the universe was created by God
A bang for your buck means that you got something great and didn't have to pay very much.
The Big Bang is the cause of everything we know - the Universe around us. If the Big Bang itself was caused by something else, we don't know about it.
it needs something to bang once and a while