Notice that the head is chipped on a rock with a corner and the corner bisects the face. Many of the drawings use natural features like corners or defects in the rocks to aid their drawings.
These must be birds.
However, these plants have a nasty thorn which went right through my shoe into my foot when we went to Kilborne Hole. They don't have any poisen so it just needed to be pulled out and we continued on our way. That lens cap is 2 1/4" in diameter so that thorn is 1.25" long!
There are thousands of petroglyphs of people, animals, fish, insects, plants, and lots of abstract and geometric designs. The ones here date back to about 900 to 1400 AD. The dark patina on the rocks was taken off using stone tools by the Jornada Mogollon people to create the petroglyphs.