Thanks a lot Mrudul ji and Dheerendra bhai for your appreciating comments......
Roopak ji
I agree with you. although lots of parameter is to be included here. such as direction of wind, the height to be achieved ...etc...I am working on that...but it was clear that down-stroke is the main thing to start flying and the bird was following the process no 3 when the vegetation was tall....

Thank you again
samrat