Why didnt these guys keep their horses tied. Am I missing something?

Spoiler
SPoiler
SPoiler
SpOiLEr


So how did Cricket die? I mean this is the second time they lost track of their horses. The first was more accidental but this time I couldnt tell if they were allowing them to run around or if they lost track of them again.

Or is it just common to let them roam around in unpinned areas?