Per the talk section above, there is some mainstream research that passes WP:RS and WP:V on pasturing stallions together as a "bachelor herd," which is already mentioned i passing in the article.  I posted the links and have not ever had the time to integrate them; I'd have no objections if someone wanted to put together a short section with those links as sources and an NPOV tone, it could be added to expand the 5th paragraph of Stallion#Management_and_handling_of_domesticated_stallions. That would actually be useful.  (talk)