Once a week, for six hours, the birds used to land, all at once, and breathe out a single sigh of relief. The trees call this time "The Hovening," a word which has long since dropped out of Human languages. During this six hour stretch, many birds die, and cats, attuned to this moment, are driven by heredity to try to escape their domestic bonds and sit beneath trees, waiting for the tasty packets to drop, inert, from the branches.
This process has halted, almost completely. In the late eighteen-hundreds, the birds began to stagger their landing patterns. They have, since, stopped the practice noticeably at all. There are, in fact, some birds which will land for hours at a time, and certain flocks which can be seen to perch of an evening, but the peculiarity which made the work of JJ Audubon possible (although he does not note it by name, taken as it was to be a given for all species of bird) has all but vanished under the sooty umbrella of industrialization.