Great blue herons engage in courtship upon returning to their nesting site. The male brings sticks to the female to refurbish the nest. He brings them; she places them. They may also do various displays for each other such as the stretch with the bill pointed skyward.
This rookery off Rte. 2 in Littleton, MA once contained dozens of nests, but over time the trees deteriorate and storms take their toll. Nest are blown down, branches break and trunks get snapped. As the trees can no longer support nests the rookery declines and the herons move on as has happened here.
© Garry Kessler