apparently, long necked creatures traveling against a dramatic sky

Longneck Migration

It is still uncertain which combination of environmental factors triggers the mass migration. Each year near the end of the dry season, every one of the normally solitary creatures begins the trek eastward–all on the very same day. Small gangs like this one eventually join with others to form great, lumbering herds numbering in the thousands. And every year, before the rains turn the lowlands into impassable mud, they reach the mountains and disperse, each one to its private winter haunt.