How are you? Remember me? I filled in for Lynn at the Mountain School for a few days in early August.

I noticed the same behavior in the dogs as you did, but I don’t think skin color is the determining factor. One week we had three African-American students at the school, and another U.S. student with brown skin, and the dogs always treated them like the other gringos. I think the dogs are conditioned to scent, like most dogs. The gringo smell of Proctor and Gamble products = GOOD person. Smell of earth and body oils = person to bark at.
That is my hypothesis. It still produces a creepy dynamic. The dog’s racism is scent based, not vision based like humans, so their outgroups are organized by different criteria.

I came across your site here doing a Google search, it is very interesting, thanks for the insights.