The birds

Any casual observer in Rome would not have failed to notice the bird clouds at dusk especially over Termini. The short explanation for these formations is staying together to guard against predators. The real advantage these formations confer (given the steep drop in predator populations in our cities) is achieving cohesion when moving together. Have you ever been in a rally or a march where the crowd straggles and fails to keep together? That does not happen with the birds and they are in mid-air. For a layman's gist read here and you can find the full scientific article by researchers from CNR,Rome here.

If you want to know why predator numbers are down, this is the link to the 'State of the World's Birds Report' by BirdLife International. Sobering.