Nature #316 Rien Poortvliet (1932-1995)

The picture has something of this: cavalry, horse, mare, animal, chestnut, portrait, stallion, mammal, bridle, equestrian, mane, nature, head, farm, equine, pony, seated.
Perhaps it’s a drawing of a brown horse with a bridle on it’s head and birds flying in the sky above the horse’s head.