How Long Do Rats Live?

by | Jun 18, 2024

Rats may be short-lived compared to other small mammals like rabbits and ferrets, but they still have an average lifespan that ranges from 1 to 3 years. Despite their relatively brief lifespans, they can proliferate rapidly which makes them a concern when it comes to infestations. While their lifespans are short, baby rats become self-sufficient by three weeks and reach sexual maturity between five to twelve weeks. This quick maturation allows female rats to start reproducing almost immediately which can lead to potentially exponential population growth.

In the United States, the most common types of rats are the Norway rat and the roof rat, both of which are often found in populated areas. These species were originally transported to North America from Europe, and they share similar life cycles despite some differences in habits. While most wild rats live around one year due to factors like predation and limited resources, those in optimal conditions can live up to 3 years. Understanding the lifespan and reproductive habits of rats is crucial for effective pest management and prevention strategies.

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What is the Average Lifespan for a Wild Rat?

The average lifespan of a wild rat is approximately one year, with female rats often living longer than the males. This relatively short lifespan is largely due to predation by animals such as hawks, owls, coyotes, foxes, weasels, and snakes, as well as dangers posed by vehicles and domestic pets like cats and dogs. In urban areas, the lifespan of rats is further reduced by various pest control methods including traps, baits, and other control measures aimed at managing their populations.

Rat Life Cycle

rat life cycle flow chart

The stages of a rat’s life involve specific developmental milestones. Here’s a breakdown of the different stages in a rat’s life cycle:

  • Week 1 – 2:
    • Rats are born blind, deaf, and hairless. During the first week, they are dependent on their mother for protection and nourishment because their eyes and ears have not opened yet. Since they remain hairless until week 2, they are commonly known as “pinkies.” By the end of week 2, their eyes begin to open, ears unfold, and fur starts to develop.
  • Week 3 – 4:
    • At this stage, young mice are known as “pups” or “kits.” They are awake and aware and start to move around and explore their surroundings. This period is crucial for learning essential survival skills like foraging for food, avoiding predators, and socializing with other rats.
  • Week 5 – 9:
    • By week 9, rats reach adulthood [1] and become independent from their mothers. Rats are social animals though, so they will seek out other rats to mate and nest with.
  • Week 6 – 12:
    • Rats reach sexual maturity by months 2-3. Males are capable of reproduction by week 5 [2] but typically are not ready to mate until weeks 6 through 10, while females reach reproductive age between weeks 8 and 12. Female rats often mate with the dominant male to ensure strong offspring.

Once sexually mature, female rats can reproduce a litter every 4 to 8 weeks, with each litter containing 6 to 12 babies. It takes 21 days for females to reach term and they can become pregnant again almost immediately after giving birth.

When Do Rats Reach Maturity?

Rats reach maturity remarkably quickly which allows for rapid population growth. Roof rats generally are sexually mature between 8-12 weeks old. They produce litters that contain 5 to 8 pups and they can get pregnant roughly 5 times a year [3]. Impressively, roof rats can become pregnant again within 48 hours after giving birth.

Norway rats, on the other hand, generally reach sexual maturity by the end of the 3 month mark. They tend to have larger litters than roof rats, producing 6 to 12 pups per litter [4]. Female Norway rats can have 4 to 7 litters annually. Like roof rats, Norway rats can also become pregnant within 48 hours of giving birth.

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Factors that can impact a rat’s lifespan include its sex, habitat, species, disease, and resources. 

Male vs Female Rats

Female rats typically have longer lifespans than males which may be attributed to the behavioral patterns of the sexes as male rats are generally less cautious in their search for food and mates. This leads them to venture further from their nests in search of food which exposes them to more potential threats. Female rats tend to stay closer to the nest to care for pups which reduces their risk of encountering predators or other dangers. Additionally, female rats’ more sedentary lifestyle and slower metabolism compared to males may contribute to their relatively longer lifespans.

Pet Rat vs Wild Rats

pet rat

Pet rats generally have a much longer lifespan compared to their wild counterparts. Pets can typically live between 2 to 4 years with some even reaching up to 7 years. In contrast, wild rats typically live less than a year due to various challenges that include predation, disease, and scarcity of food and water. Additionally, wild rats lack the veterinary care that pet rats receive, which further shortens their lifespan. Domesticated rats benefit from a safe environment, consistent food supply, and medical care which contribute significantly to their extended life expectancy.

Rat Species

The species of rat can also significantly impact its lifespan. The differences in habitat and lifestyle between these species can influence their average lifespans.

How Long Do Brown Rats Live?

Brown rats, also known as Norway or sewer rats, generally have an average rat lifespan of 2 years [5].  Brown rats tend to stay under cover in burrows and sewers, which may protect them from predators and contribute to their longer lifespan.

How Long Do Black Rats Live?

Black rats, known as roof or tree rats, generally live for about 1 year or less [6]. In contrast to brown rats, black rats live in higher places like tree branches and roofs which exposes them to more threats from predatory birds and cats.

Rat Diseases

Rats are susceptible to various diseases that can significantly shorten their lifespan. These diseases can spread rapidly within rat populations, especially given their social nature and close living conditions. Some of the most common and deadly diseases that affect rats include:

  • Heart Disease: A prevalent cause of death in rats that is often due to genetic defects. These defects can be passed down to younger generations of rats which can result in entire populations being impacted due to interbreeding.
  • Cancer: Rats are so prone to multiple types of cancer that this is one of the reasons that they are used as test subjects in cancer research. They can be afflicted with cancers that affect different body parts including mammary glands, pituitary glands, and squamous cell carcinoma [7].
  • Respiratory Problems: Chronic respiratory disease (murine respiratory mycoplasmosis) caused by bacterial infections is a significant health issue for rats. Symptoms include sneezing, sniffling, lethargy, labored breathing, and weight loss. There is no cure and the disease can be fatal, especially when compounded by other infections.
  • Pneumonia: Several bacteria and viruses can cause respiratory infections and pneumonia, leading to symptoms like sneezing, labored breathing, rough hair coat, and weight loss. These infections are typically severe and often incurable without supportive care and antibiotics to manage symptoms.

Parasites

Parasites can significantly impact the health and lifespan of rats, leading to issues like malnourishment, bleeding, and even death. Here are some common parasites that infect rats [8]:

  • Protozoa: These microscopic organisms can cause various diseases and lead to severe health problems in rats.
  • Tapeworms: These intestinal parasites can cause malnutrition and other digestive issues in infected rats.
  • Pinworms: These small worms infect the intestines and cause discomfort and potential health issues.
  • Fleas: Though uncommon in pet rats, fleas can infest rats if they come into contact with wild rodents. This can lead to itching and potential anemia.
  • Lice: Blood-sucking lice are common in wild rats and can cause intense itching, restlessness, weakness, and anemia.
  • Mites: Several types of mites can infest rat skin and fur, causing itching, inflammation, and scabbing, especially when the rat is stressed or has a weakened immune system.

These parasites not only affect the health of individual rats but can also spread rapidly within rat populations.

Resource Availability

rat eating food

Resources play a crucial role in the survival and reproduction of rats. When food and water are abundant, rats can thrive, procreate frequently, and maintain robust health. However, in resource-scarce environments, rats face significant challenges. Lack of sufficient food and water can lead to malnutrition, weakened immune systems, and death from hunger or dehydration. In their quest to find new sources of nourishment, rats often expose themselves to predators, traps, and other dangers which can also significantly shorten their lifespans.

How Long Can Rats Live Without Food?

Most rats can live for approximately 4 days without eating [9]. Beyond this period, they are unlikely to consume enough calories to sustain themselves. In the face of starvation, rats will become increasingly desperate and eat almost anything available.

How Long Can Rats Live Without Water?

Rats generally have a relatively low need for water because they get most of their hydration from the food they consume. However, if food is unavailable and rats are unable to secure hydration, then a rat may die from thirst in 2 days [10].

How Long Can Rats Survive After Eating Poison?

Rats face significant threats not only from natural predators but also from human interventions like traps and poisons. Poisoning is a common method used by pest control to manage rat populations. However, rats typically do not die immediately after consuming rodenticides. The time it takes for rats to succumb to the poison depends on the type of poison used.

  • Anti-coagulants: These rodenticides are slow-acting and work by causing internal hemorrhaging. After ingestion, these poisons usually take several days to kill the infected rat.
  • Bromethalin: This neurotoxic rodenticide affects the central nervous system, leading to liver and brain damage. Death typically occurs within a few hours after ingestion.
  • Vitamin-based: Overdosing on vitamins like A, D, E, and K typically kills rats within 24 hours.

It’s crucial to use these poisons responsibly as they can pose a threat to non-target animals. Place baits outside and ensure that rodent exclusion measures are in place to prevent rats from consuming poisons and then moving inside to die.

Contact Absolute Pest Management if You Are Dealing with Rats

If you’re dealing with a rat problem and need expert assistance, don’t hesitate to contact Absolute Pest Management. Our experienced team of rodent control experts are equipped with the knowledge and tools to effectively eliminate rats and prevent future infestations. We offer comprehensive rat control solutions tailored to your specific needs. We have offices in Austin and Buda, Texas and serve the surrounding communities. Reach out to Absolute Pest Management today and take the first step towards a cleaner, healthier space.

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Rat Lifespan FAQs

  • Can a rat live for 12 years?
    • There is no rat species that can live for 12 years. The typical lifespan of a rat is much shorter, with wild rats living around 1 year and pet rats living between 2 to 4 years. Even under optimal conditions, rats do not live beyond a few years.
  • How long does a pet rat live?
    • A pet rat typically lives between 2 to 4 years. With proper care, a safe environment, and good nutrition, some pet rats can live up to 3 or even 4 years, although this is less common.
  • How long do rats live naturally?
    • Rats in the wild typically live around one year due to predation and harsh environmental conditions. In more protected environments like in captivity, they can live up to 2 to 4 years.

    Sources

    [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8388463/

    [2] https://www.queensu.ca/animals-in-science/policies-procedures/sop/rats/10-24

    [3] [8] https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1775-2018.pdf

    [4] https://www.scph.org/sites/default/files/editor/Norway%20Rat%20Handout.pdf

    [5] https://animaldiversity.org/accounts/Rattus_norvegicus/

    [6] https://pestweb.com/pests/1155/roof-rat

    [7] https://www.merckvetmanual.com/all-other-pets/rats/disorders-and-diseases-of-rats

    [9] [10] https://www.ctahr.hawaii.edu/nelsons/glossary/Rat_rats.htm

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