Because of the weather.
the mayans were really aware of the birds falling
Yes. Totally.
clouds or birds and maybe rain or snow falling or even hail
Only if the end of days follows the birds falling. Let's face it, sometimes things happen and we don't ever know if there is a reason. Accept this in humility and move on with your life.
Falling Sky was created in 1998.
The Sky Is Falling - album - was created in 1980.
Snow falling from the sky is called snow. THe act of snow falling is called snowing.
None that I can recall. Revelations 19:21 is the only bird specific passage I know of. However in it, the birds eat the flesh of the dead.
The Sky Is Falling - Sheldon novel - was created in 2001.
Stars Falling From the Sky ended on 2010-03-16.
Stars Falling From the Sky was created on 2010-01-04.
Sky Starts Falling was created on 2005-09-12.