becomes the background while the deer becomes the subject. That interpretation is perfectly reasonable, but it can make the second pattern harder to detect because the hidden face depends on parts of the image the viewer has already decided are less important.
A useful first strategy is therefore surprisingly simple: stop searching around the deer. Instead, examine the entire scene as though every section could contain meaningful information. Begin on one side of the picture and gradually move your attention toward the opposite side. Look at the spaces between trees