Young Swallow

This young Swallow was one of two,sat on a farm gate quite peacefully.I thought they were just resting,when all of a sudden they began flapping their wings in a frenzied manner.Next thing I know,the adults shot in and feed the youngsters on the wing!
I had never experienced anything like it before in my 66 years!

Nikon D800 + Sigma 170-500 APO F5-6.3 + a mono pod for stability. lol
500 mm in dx mode = 750mm 1/400 sec.@ f8, ISO 1100