DTY Rodent Management
What do you remember or what did you forget?
Assure your competitive success with knowledge of rodent behavior


For thousands of years, mice and rats have been two of the most successful life forms on the planet. They have not only competed, but in some cases outcompeted, human endeavors. The phenomenal success of mice and rats has much to do with their unique biology, sexual reproduction and mating, reproductive system, gestation and birth, and resilient nutritional requirements. Especially significant to their success is complex behavior.

Rodent habitation and attributes

Human residential and commercial environments are artificial or created for comfort. Artificial conditions are attractive to mice and rats since there is stability of temperature and humidity. Mice and rats are also attracted to the foods consumed by humans.

Both mice and rats are inquisitive, social mammals. Quickly adapting to environmental conditions, novel situations are always of phobic or critical interest. Movement toward the novel stimulus indicates curiosity. Both species will rear-up, pushing their noses high to sample for air cues.

Mice and rats are naturally tidy, spending hours each day grooming themselves and one another. They practice coprophagy (eating of feces). Areas of defecation and urination are present throughout their territories, but communal sleeping areas are surprisingly clean and rarely soiled.

Mice and rats are basically nocturnal, but mice usually display more diurnal, or daytime, activity. Activity is exhibited in cycles, and rest occurs throughout the day and night.

Mice and rats tend to sleep five to 10 minutes, wake up, adjust posture and drift back to sleep. In groups, sleep is in communal piles, with individuals gradually exchanging positions over time. This always-on-alert behavior favors prey species or species in an environment replete with predators.

Signs of conflict

The world of mice and rats is often one of conflict and brutality. Necropsy (examination of the body after death) of mice and rats generally shows evidence of pathogens, pathologies and wounds or scarring resulting from numerous conflicts.

In conflict, mice usually inflict bite marks from behind, on the tail or over the rump area. Death sometimes occurs, but generally lower ranking mice will lose weight because ongoing attacks make feeding difficult. Rats usually face each other when settling disputes, and the bite wounds tend to be around the head and shoulders. Fights between rats are rare, although more likely between males. Post-parturient (after giving birth) females in communal arrangements also may fight.

Signs of sickness

Healthy mice and rats spend time each day keeping their coats clean. As they become ill, their coats become ruffled and unkempt, and they lose precious body weight or waste away. Activity gradually decreases until they become reluctant to move and finally assume a characteristic posture. The back is hunched-up, fur ruffled, the head lowered and the eyes squinting or closed. Respirations become more pronounced or labored and rapid.

The house mouse (Mus musculus) is a major pest in rural areas and on farms. This is especially the case in and around poultry and pig rearing operations. Recent research demonstrated that rural populations of Norway rats (Rattus norvegicus) are more likely to carry disease than urban populations. This is because rural populations tend to be more dense and difficult to manage.

Rodent and pest management impact

Global rodent control is estimated to run in the billions of dollars. In another realm, mice and rats are beneficial to humans as an essential research animal in medicine. Additionally, rodents are an essential part of ecosystem balance.

Pest management is undertaken to prevent pest damage. If the damage is a threat to human health, society often demands a zero tolerance of the pest. If the damage is purely economic, it may be tolerated at a low level. For you, the pest management professional, what you remember about mice and rat behavior assures your competitive success over theirs!

Stuart Mitchell, D.O., DVM, PsyD, BCE, is an entomologist, veterinarian, observing physician and consulting clinical psychologist, and a regular contributor to Pest Management Professional's Direct to You series.

PMP’s Direct To You provides pest management professionals with educational refreshers on timely and critical topics essential to operational success. This content is not be used as a substitute for obtaining legal advice from an attorney licensed to practice where you live. Look for the content-rich PMP Direct To You archives at mypmp.net/direct-to-you-archive.

This newsletter was produced by North Coast Media’s content marketing staff in collaboration with Bell Laboratories.

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