Well, I'm far away from being an expert :). But in my work I take care of some exotic butterflies. This is a beautiful butterfly for sure. :) It doesn't look like monarch to me. Maybe it is a similar butterfly, maybe I cannot recognize it from this picture. Monarch butterflies stick together and always know where to fly. So this is probably a different species of a butterfly. :) Butterflies use their wings as small solar panels, they absorb energy from sun. So it has probably found a great place to "charge its batteries" :D.