The zebras are together. 
The zebras are walking. 
Brown grass covering the ground.
zebras out on the plains
multiple zebras out on the plains
many zebras out on the plains
plenty zebras out on the plains
several zebras out on the plains
zebras are in a field 
a herd of zebras 
zebras in a grass field 
the zebras have a striped hide 
a herd of zebras grazing on a dry, grassy field while other zebras walk along the open plains