Obsidian Boar carcass crop rate in Ulfheim very low - bug?

I spent 45 minutes farming the boards in the SW corner of Ulfheim. I ended up with 25 boar carcasses, of which about half dropped from obsidian boars as opposed to Grand Old Boars. I got no obsidian boar carcasses at all. Which suggests that the obsidian carcass drop rate for Ob Boars is in the single digits. That could be intentional, but since the Ob Bears and Ob Wolves in the same scene seem to drop an obsidian carcass about 1/3 - 1/2 the time, I thought I'd ask: Bug or Feature?

On the good side, I'm in bacon for the foreseeable future. (Could we maybe please get a more useful recipe for boar as opposed to farmed pigs? As combat critters they ought to be in the 2hr food category like wolves, crocs, etc.)