Group Behavior Biology

What is Group Behavior in Biology?

Let's start with the definition of group behavior.

Group behavior is opposed to individual behaviors, which involve single organisms carrying out behaviors that benefit themselves.

Cooperative social behaviors are the type that tends to benefit groups the most, though three other behaviors are also recognized:

• Altruistic behaviors benefit the receiving individual(s) while being detrimental to the donating individual(s).

• Egoistic behaviors are detrimental to the receiving individual(s) but beneficial to the donor(s).

• Revengeful behaviors are detrimental to both donors and receivers

Cooperative behaviors are beneficial to both the receiving individual and the donor. So, you can see why cooperative social behaviors are vital to the proper functioning of groups!

Group Behavior Benefits and Detriments

There are benefits and disadvantages to group living. So, let's talk about this.

Organisms living in groups can have decreased levels of predation since potential predators can become overwhelmed or even confused by large groups of prey animals. Even if the level of predation remains constant, the "dilution effect" created by the presence of more individuals decreases the risk of predation for each individual.

Larger groups also have more individuals keeping watch for the presence of predators. Larger groups, however, have a more difficult time hiding from predators.

Group living also means more individuals are available to forage or hunt for food, though this increases intraspecific competition for and depletion of resources. Group living (and therefore, group behavior) can also increase the risk of spreading disease due to so many individuals living close to one another.

Types and Examples of Group Behavior Biology

There are generally considered to be four types of group behavior in animals:

1. Anti-predator behaviors

2. Foraging/hunting behaviors

3. Increased movement efficiency

4. Benefits to social interactions.

Group Behavior in Animals: Anti-predator Behavior

As stated above, living in groups can provide some protection from predation. Large groups of prey may be able to physically overwhelm potential predators.

Figure 1: Giant river otters (left) are able to repel attacks by yacare caiman (right) due to coordinated group defensive behavior

Another way large groups can minimize predation is by having more individuals keep watch for predators.

Lastly, when groups are very large, even constant rates of predation may still result in decreased chances of predation for individuals, though the chances are not uniform throughout the group. Vulnerable individuals and those along the group's periphery have much higher chances of being predated.

The major predators of coatis are jaguars (Panthera onca) and mountain lions (Puma concolor), which they encounter throughout their range and account for over half of all coati predation.

A study found that lone coatis were significantly more likely to be predated by jaguars and pumas than those in groups. Group living provides coatis with numerous protections from predation by these cats, ranging from mitigation (increased vigilance and alarm calling) to defensive (overwhelming and even attacking the cats).

_{Figure 2: White-nosed coatis (left) are capable of defending themselves from predatory attacks by big cats, such as the jaguar (right), thanks to living in groups.}

Group Behavior in Animals: Hunting and Foraging Behavior

Having more individuals in a group means that more energy can be focused on foraging for food (e.g., fruits, nuts, and vegetables) or cooperative hunting.

Foraging in groups can increase the food resource yield and decrease the time needed to forage. In addition, it can allow for important learned behaviors to be passed on to the next generation from older individuals.

Group living also allows for cooperative "pack hunting" behavior. Predators such as chimpanzees, lions, wolves, whales, and possibly even one crocodile species participate in pack-hunting behavior. Pack hunting involves small groups of predators working together in groups to subdue prey species. This allows these predators to subdue larger prey species than they would be capable of subduing alone.

Group Behavior in Animals: Increased Movement Efficiency

Living in groups allows organisms to coordinate movements better on a large scale. This is achieved through the monitoring of the movements of neighboring individuals. Animals such as flocks of birds, schools of fish, and some insects have increased movement efficiency due to group coordination.

Group Behavior in Animals: Benefits to Social Interaction and Structure

Life in groups can have many benefits to social interactions and structures. Some examples of benefits include increased emotional satisfaction and bonding, mutual cleaning, and a more stable lifestyle. However, animals that naturally live in groups tend to only thrive within a group and may suffer mental and physical health issues if placed in isolation.

One of the most notable features of bonobo social behaviors is the general lack of aggression and only mild conflict that occurs between individuals and groups, even between males. This is unique among primates, including humans. Bonobos also frequently engage in sexual activity as a social practice rather than an exclusively reproductive practice.