All animals are subject to cognitive overload: too much information upon which to decide. Factor analysis becomes more difficult when factors pile up.
While easy decisions may be better made by individuals, collective intelligence surpasses the ability of any individual when a larger data set needs to be considered.
There is also the aspect of convergence to statistical normalization with collective intelligence, as outliers are smoothed. Averaging human estimates, such as guessing the number of beans in a jar, tends to converge to the correct answer with more guesses.
Many bird species fly in flocks. Some populations do so for the sheer fun of it: soaring in near unison with friends and family.
There is no leader in a flock. A bird within may decide it is time to turn and neighbors join in. The decision propagates like a wave, at a speed that depends upon how parallel the birds’ paths are.
When difficult decisions need to be made, social insects invoke collective wisdom, and decide together.
Individual insects compare options and make decisions all the time, but some things are hard to figure. Social insects have a significant advantage when making decisions that affect a local population.
Big decisions that affect the colony are left to the colony. For a new nest, honeybees and ants display collective wisdom in picking a site.
A colony can wisely decide between 2 locations even if no single member has been to both sites. The enthusiasm that scouts display for a specific site weighs heavily in the decision. That especially makes sense since all involved have the same criteria in mind.
Rock Ant Real Estate
Whereas humans are subject to housing bubbles, rock ants are rational real estate mavens. They continually monitor their neighborhood to know when new homes are available. Moreover, their search effort is attuned to the quality of the nest they currently inhabit. They put more effort into finding new digs when they are in a poor one, and conversely search less when living luxuriously.
Rock ants teach one another using tandem running: a learner provides interactive feedback to the teacher that it is following. Tandem running is a typical way of telling another rock ant the location of a food source.
Large shoals of fish often move fluidly as a collective. (Whereas a school of fish are of the same species, a shoal of fish stay together for social reasons.) Individuals concentrate on keeping close while maintaining a certain personal space from other fish.
Spacing between fish is important in shoals. If a shoal becomes overcrowded, chaos sets in, as each animal cannot determine a safe direction.
Shoal leadership is efficient, regardless of shoal size. A relative few individuals in a shoal decide where to feed or how to flee. The precise dynamics of this follow-the-leaders swarm intelligence are not fully understood.