Nest complete, the blue jays spend hours on end in the wax myrtles. They defend their honeymoon suite with harsh calls and indignant attacks–innocent warblers fare no better than foraging crows. Rabbits aren’t allowed to graze in the yard, and the merest quiver of a squirrel whisker raises apocalyptic alarm.

Between these bouts of aggression, the lovers perch together and mumble softly to each other. They feed each other, public displays of “affection” that make me wonder about their behavioral chemistries. How does a body cope with such abrupt changes? They interrupt bonding with outbreaks of tumultuous fury, then switch back to bonding, over and over again in the course of a day. In the span of a minute, sometimes. The physiologic stress must be enormous, and yet it seems to work for them. How?