“An ecologist studying flamingos on Kenya ’s Lake Nakuru has noticed an interesting phenomenon. Every year, when the time comes for migration, a few flamingos start the process by taking off from the lake. Since none of the others take any notice, they soon turn round and come back.
The next day they try again. This time a few others straggle along with them but, again, the vast majority just carry on with business as usual, so the pioneers return to the lake. This trend continues for a few days. Each time a few more birds join in but, since the thousands of others still take no notice, the migration plan is aborted.
Finally, one day, the same few birds take off again. This time however, the tiny increment to their number – maybe just one extra flamingo – is enough to tip the balance. The whole flock takes flight. The migration begins.”