There are other coronal holes in these images. The coronal hole at the south pole of the Sun got smaller going from March to June. These polar coronal holes shrink at solar maximum and then reappear at solar minimum.
Coronal holes, in all of their shapes and sizes, will become more frequent as the Sun starts to reduce solar activity back toward another solar minimum.
Like figures in clouds, these shapes are fun to find. You can look for coronal holes at the SDO data website. They show up best in the 3-color images.
You can read more about coronal holes in another blog post.