If a male rat is aggressive toward other males, will he be aggressive toward humans? Definition Agonistic behavior refers to the complex of aggression, appeasement and avoidance behavior that occurs between members of the same species.
Agonistic behavior is a much broader term than "aggression," which refers to behavior patterns which serve to intimidate or damage another for more, see McFarland, Social agonistic behavior Agonistic behavior behavior involves several actions, or motor patterns, including chasing, sidling, boxing, biting, and kicking, as well as audible and ultrasonic vocalizations.
Agonistic behavior can occur between rats in a colony, and between resident rats and intruders. The lowest intensity encouters are chases. As the intensity increases, you may see stand-offs and physical contact like boxing and sidling. These physical encounters may escalate in rare instances into a fight. Aggressive neck grooming is a low-intensity form of agonistic behavior.
Grooming consists of rapid little nibbles in which the groomer seizes folds of neck skin between his teeth Miczek and Boer The groomed rat remains immoble and may peep or squeak softly. Any sudden movement by the groomed rat may trigger a bite and kick from the groomer.
A low intensity agonistic interaction is a chase. Many agonistic interactions consist of one rat chasing another for a few seconds. The chased rat flees and either outruns or hides from the pursuer, or sometimes the pursuer desists.
If the pursuer catches up, he may nip or bite the rump of the fleeing rat and may attempt to engage him in an encounter. Sometimes, the pursuer may mount the fleeing rat. If the chased rat holds his ground, chaser and chasee may have an encounter. A pursued rat may turn to face the pursuer, initiating a nose-off. The defending rat may show an open-mouth tooth display , with long squeaks and sometimes hisses.
Sometimes the tails of both rats writhe on the ground, and both rats' fur may be piloerect. Frequently the encounter goes no further, and one of the rats usually the pursued one flees. If neither rat flees, the encounter may escalate with physical contact. The subordinate rat, especially if he is young or the rats are confined in a cage, may roll over into a belly-up roll.
I've found among my rats that most of the few encounters that get this far end here, with the flight of the pursued rat. After the flight another sequence may occur, and on a few occasions combinations of chases, sidling, and flight have lasted for tens of minutes or even an hour or more. A variation on the sidle sequence is seen on ledges such as shelves and hammocks. On ledges, the sidling rat crowds the other toward the edge.
This may be a very slow process, with the sidling rat maneuvering a fraction of an inch at a time, with long pauses when nobody moves. If the second rat does not jump off the ledge himself, he will be pushed off. Sometimes the pursuer will follow the second rat around the cage, pushing him off ledge after ledge. If the second rat resists, the encounter may escalate. Rarely, physical contact may escalate into a fight. On a handful of occasions the encounter escalates beyond the sidle-and-kick stage, and the two rats close into a fighting ball , in which the attacking rat may bite the other's flank or rump.
These fights are usually brief lasting just a few seconds and end with one rat fleeing, hiding and staying staying quiet and subdued for a while -- an hour or more. Offensive and defensive tactics The immediate goal of serious fighting is the attack and defense of the rump and lower flanks. The goal of the aggressor is to inflict a bite on the rump, and the goal of the defender is to prevent such a bite Blanchard et al.
Used to gain access to another rat's rump or flank to inflict a bite. Such tactics include chasing , sidling , kicking , pushing and biting. Usually used by the dominant rat on subordinates. Used to protect one's rump from attack. Such tactics include fleeing , hiding nose-offs and boxing interposing whiskers between attacker and rump , belly-up rolls interposing belly between attacker and rump , and bites directed at the attacker's face. Subordinate strategies In groups of three rats, subordinates tend to employ one of two strategies in their relationship with the dominant rat.
Subordinates either avoid the dominant rat or they stay close to him. Omegas who cannot escape may be so severely attacked and harassed that they die Adams and Boice However, in some cases, if the dominant rat is removed, an omega subordinate may be more likely than a beta to rise to become the new dominant rat. In contrast to omegas, betas become fully submissive toward the dominant rat, who in turn tolerates their presence more Pellis et al.
So, the two strategies have different costs and benefits. Beta subordinates live in relative peace with the dominant rat and tend to gain more access to food and females. Omegas, on the other hand, tend to be the target of more aggression from the dominant rat. The omega and the alpha may maintain an uneasy truce. But the omega may be in a better position to take over the dominant's role if it becomes available Pellis et al. What causes a rat to adopt one strategy or the other? Rats vary in temperamental factors that influence aggressiveness and boldness, which may have a genetic component.
In colonies of rats that differ in boldness, the boldest rat may become dominant, intermediates may adopt the omega strategy, and the least bold may become betas Pellis et al In any case, dominance is usually not correlated with body size e.
Stewart and Palfai Agonistic behavior within a colony How common is it? Agonistic behavior is actually not very common between rats in an established colony. The most aggressive animal in the Blanchard study spent less than 2 minutes per hour in aggressive interactions. Alberts and Galef established colonies made of pairs of wild-stock brothers. If one of the males was removed for 24 hours, then replaced in the home cage, the remaining brother was not aggressive toward the returnee.
Instead, both rats simply began feeding. Sex differences Males are much more likely to engage in agonistic behavior both offensive and defensive than females. In Blanchard et al. Males tend to develop dominance hierarchies, which are less common in females.
In mixed-sex colonies, resident males are far more likely to attack intruders than resident females. However, this low level of female aggression toward intruders may be due to the presence of males. Females living in all-female groups do attack intruders Blanchard et al. Males rarely bit females in the Blanchard et al. Only 5 out of 18 females were bitten by males bites each , and these bites occured only during the first month after the colonies were formed.
In contrast, male-male biting was much more frequent 0. Age and aggression within a colony In general, young male rats play fight together from age 5 weeks to around age months. Play fighting isn't serious, nobody consistently wins or loses, and nobody gets injured. As the young males approach social maturity at around months of age, however, their fighting becomes serious, with chasing, sidling, and biting, and one rat emerges as a consistent winner.
In this way a stable, long-term dominance hierarchy emerges between the males. The dominant male also tends to be the most active and to copulate most frequently with the females. Females, for their part, tend to behave less aggressively toward each other, but a female dominance hierarchy may emerge while they are pregnant or lactating. Here are two studies of rats in a semi-natural setting that examine dominance in mixed-sex colonies of rats over the rats' entire lifespans: Adams and Boice established a mixed-sex colony of 4 male and 4 female 45 day old albino rats in a large, outdoor semi-natural enclosure and recorded the dominance relationships among the rats and their offspring every day for 15 months.
Young rats play fight, but their play fighting doesn't predict adult dominance: They observed that young male rats engaged in lots of play fighting: There was no sidling, chasing, or biting. None of the rats were injured.
Winners and losers were frequently reversed, so that no rat was consistently dominant. These play-wins and play-losses did not predict the adult male hierarchy at all. Females didn't interact with each other as much, but when they did they also play fought. At social maturity, fighting turns serious, and a stable male dominance hierarchy emerges: When the rats approached social maturity at around age months, adult aggressive behavior made its appearance: A stable social hierarchy emerged, with one male rat consistently winning contests over the others.
This male became the dominant rat, the other three became subordinates. Two were socially active "betas," while one was a socially isolated, viciously attacked "omega.
Interestingly, five weeks after the hierarchy was established, the dominant male became ill and stayed in his burrow for a week. During his absence, two of the subordinates started confronting each other and one became dominant over the other. When the original alpha male got better and emerged from his burrow, the new alpha male severely attacked him, leading to the original alpha's death the following day. This new alpha remained dominant in a stable hierarchy for the rest of the study.
This male copulated with females twice as often as any other male. When new males were introduced, the resident males, especially the resident dominant male, attacked them. The newcomers' activity was greatly suppressed for several months and they spent most of their time underground. When new females were introduced, one resident female attacked them persistently, but these attacks waned after a few days and the new females were eventually accepted.