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A: I don’t know exactly why your two geldings are different. But defecation habits are so interesting! Here’s a little background: Horses grazing at will tend to defecate and move on. Domestic horses at pasture tend to have latrine areas where there’s a concentration of manure piles. Since horses tend to avoid grazing near manure piles, this area is usually undergrazed, despite often having some pretty nice grass due to the nutrients from the manure.

Stallions have an elimination-marking sequence when they encounter a manure pile from another horse, which includes a ritualized sequence that goes something like this: sniff, or maybe paw at it, show a flehmen response, defecate or urinate on or near the pile, maybe sniff it again, and move on.

You will also commonly see “stud piles” of manure. A singly housed stallion will make these piles of manure, and they will also be formed by multiple stallions defecating over each others’ manure.  You’ll see these stud piles along fence lines, at gates, and in open areas where there are common stallion or harem group crossings. I saw stud piles near an asphalt road in a Mustang-populated area outside Reno, Nevada, and learned that was a favored crossing for the local bands and harem groups. Defecation might also occur amidst agonistic encounters between stallions