"The pictures weren't staged. The accompanying German text on these pages explains how the fawn's mother was killed shortly before it's birth and the fawn was then raised in a rural town with help from townspeople (this part is not so clearly explained). The wild rabbit showed up one day. At first the two just grazed in the same area and after a while got closer until they became "friends". They grazed together and kept each other company the whole day, the rabbit built a nest next to the deer instead of burrowing and other cute stuff like that. The author (who is also the photographer) mentions that the two could have formed this friendship to be able to better protect themselves from predators by warning each other and also the deer helped the rabbit have easier access to food in the winter.

Spoiler: Eventually when the fawn was old enough it was sent to a park where it would be released into the wild. The second to last picture shown here, shows how after the fawn had been anesthetized for easier transport and despite strange humans being around, the rabbit went up to the deer and supported its sleepy head "as if it were saying goodbye"