The moment those birds took off, it looked like a big wave shining in the sky.
The instant the birds took flight, the sky looked like a big shiny wave.
ーThe moment those birds took off, it looked like a big wave shining in the sky.
「鳥達が飛び立つ瞬間、空にきらめく大きな波のように見えた」
to take off で「地面から飛び立つ」
a big wave shining in the sky で「空にきらめく大きな波」
ーThe instant the birds took flight, the sky looked like a big shiny wave.
「鳥達が飛び立った瞬間、空は大きな輝く波のように見えた」
to take flight で「飛び立つ」
a big shiny wave で「大きな輝く波」
ご参考まで！
カナダ 
