They made out a shadowy form in front of them.

他们隐约认出了前面的模糊人影。

《牛津词典》

Zebra's stripes are a form of camouflage, making the animal very difficult to see in the shadowy tall grass of the African plain.

斑马的条纹是一种隐蔽形式，使斑马在非洲平原上的高高的阴影晃动的草丛中，很难被发现。

youdao

When night falls on Harar, the labyrinth alleyways of the walled Old Town fall silent, and the shadowy form of a hyena slinking through the narrow streets is not an uncommon sight.

BBC: Africa��s wildlife in the raw