While the flock is feeding, a few individuals stand sentry in trees nearby to alert others to danger with raucous calls.
His file says: "The detainee was apprehended after a name similar to his was heard on a radio intercept thought to be originating from a group of individuals acting as sentries, reporting US troop movements to the Taliban.
As such, the individual engineer stands as sentry to ensure that the public is protected from unwarranted risks.
In other words, if the whole-group advantage outweighs the cost to any individual bird of being a sentry, then the sentry gene will prevail.
For example, groups of birds benefit from increased vigilance if groups size is larger, as each individual has to be on sentry for less amount of time, but interference competition puts a limit on the size of the group [ 71].
But to more than 200 individual investors, it was the bank that should have stood sentry over their money.
The sentries were optimistic.
At Versailles, German sentries.
More sentries, more metal detectors.
The sentries at the gate saluted Naquib.
