The most interesting feature of behavior to watch is the route that they take. The butterfly flight paths should be in principle chosen carefully for the survival value (i.e., in search of nectar, possible mates, and avoiding predators), and yet are full of rapid turns and apparently whimsical perturbations at the same time.
The beauty of butterfly watching is that you never know when and from where they are coming. Every corner of your vision becomes a potential route of entry for the airborne creature. By waiting for the butterflies, your sensitivities are kept alive and vibrant.
Yesterday, I was lucky to observe a beautiful specimen of Great Mormon (Papilio memnon Linnaeus). This magnificent butterfly used to be more southern bound. Probably due to the effects of global warming, we can now observe Great Mormons in Tokyo, too.
Thus, while jogging among the greens, I can sometimes encounter a messenger from the south.
A Great Mormon.