Flying phenomenon

Sometimes when I see a flock of birds (geese?, I am not an ornithologist) flying together, heading wherever it is that they are heading (I presume the local bar), suddenly, and all at once, the whole flock will change direction, or they will all decide to head to the nearest large tree, simultaneously. I take it that they probably don’t have someone quacking out orders to them. How do they do this? And with such precision and timing almost as though Spock has linking their ‘bird brain’ and told them, now we turn here. It is quite astonishing to watch, if you absorb the event rather than simply observe the happening.

See my Staff Report: How does a flock of birds wheel and swoop in unison?

Large birds, such as geese, that fly in formation, may actually have flock leaders of sorts - older and more experienced birds that the other birds follow. In large flocks of small birds, such as starlings, movements are arrived at by a sort of consensus - when a critical number of birds starts flying in one direction, that’s the way the flock will move.

Flocking and schooling behaviours can appear terribly complex and they can look as if there is some central coordinating intelligence, but in fact they can be mathematically modelled using only a handful of simple rules, for example, something like this:

-Move forward no slower than 10cm/s and no faster than 1m/s
-Change direction only by turning (i.e. face somewhere else and move forward - no lateral slides)
-Try to stay no more than 50cm away from the nearest member of the group, but no closer than 20cm to any individual.
-Move away from a predator if it approaches within 3 metres

Will result in a coherent group of individuals that reacts as if it is a single amorphous organism.

For more info on this, try googling ‘boids’ - there are a number of simulations out there you can play with to get a feel for how it works.

There’s a link in the Staff Report:

Boids: http://www.red3d.com/cwr/boids/
(includes many additional references)