The brown rat (Rattus norvegicus), also known as the common rat, street rat, sewer rat, wharf rat, Hanover rat, Norway rat and Norwegian rat, is a widespread, common species of rat. One of the largest muroids, it is a brown or grey rodent with a body length of up to 28 cm (11 in) long, and a tail slightly shorter than that. It weighs between 140 and 500 g (4.9 and 17.6 oz). Thought to have originated in northern China and neighbouring areas, it has now spread to all continents except Antarctica, and is the dominant rat in Europe and much of North America, having become naturalised across the world. With rare exceptions, the brown rat lives wherever humans live, particularly in urban areas. It is omnivorous, reproduces rapidly, and can be a vector for several human diseases.

Studies of wild rats in New York City have shown that populations living in different neighborhoods can evolve distinct genomic profiles over time, by slowly accruing different traits.

Naming and etymology

The brown rat was originally called the “Hanover rat” by people wishing to link problems in 18th-century England with the House of Hanover. It is not known for certain why the brown rat is named Rattus norvegicus (Norwegian rat), as it did not originate from Norway. However, the English naturalist John Berkenhout, author of the 1769 book Outlines of the Natural History of Great Britain, is most likely responsible for popularizing the misnomer. Berkenhout gave the brown rat the binomial name Mus norvegicus, believing it had migrated to England from Norwegian ships in 1728.

Though the assumptions surrounding this species’ origins were not yet the same as modern ones, by the 20th century, it was believed among naturalists that the brown rat did not originate in Norway, rather the species came from central Asia and (likely) China.

Distribution and habitat

Possibly originating from the plains of northern China and Mongolia, the brown rat spread to other parts of the world sometime in the Middle Ages. The question of when brown rats became commensal with humans remains unsettled, but as a species, they have spread and established themselves along routes of human migration and now live almost everywhere humans are.

As it spread from Asia, the brown rat generally displaced the black rat in areas where humans lived. In addition to being larger and more aggressive, the change from wooden structures and thatched roofs to bricked and tiled buildings favored the burrowing brown rats over the arboreal black rats. In addition, brown rats eat a wider variety of foods, and are more resistant to weather extremes.

In the absence of humans, brown rats prefer damp environments, such as river banks.[86] However, the great majority are now linked to man-made environments, such as sewage systems. In addition to sewers, rats are very comfortable living in alleyways and residential buildings, as there is usually a large and continuous food source in those areas.

It is often said that there are as many rats in cities as people, but this is considered an urban myth for most cities. Brown rats in cities tend not to wander extensively, often staying within 20 m (66 ft) of their nest if a suitable concentrated food supply is available, but they will range more widely where food availability is lower. It is difficult to determine the extent of their home range because they do not utilize a whole area but rather use regular runways to get from one location to another. Urban rat research is considered to be challenging due to their significant global population size and spatial distribution patterns. There is great debate over the size of the population of rats in New York City, with estimates from almost 100 million rats to as few as 250,000. Experts suggest that New York is a particularly attractive place for rats because of its aging infrastructure and high poverty rates. In 2023, the city appointed Kathleen Corradi as the first Rat Czar, a position created to address the city’s rat population. The position focuses on instituting policies measures to curb the population such as garbage regulation and additional rat trapping. A 2024 study using data from Vancouver found that most municipal complaints about rats were related to garbage, and the rats were often viewed as a symptom of a community issue.

Megathreads and spaces to hang out:

reminders:

  • 💚 You nerds can join specific comms to see posts about all sorts of topics
  • 💙 Hexbear’s algorithm prioritizes comments over upbears
  • 💜 Sorting by new you nerd
  • 🐶 Join the unofficial Hexbear-adjacent Mastodon instance toots.matapacos.dog

Links To Resources (Aid and Theory):

Aid:

Theory:

Financial Support to the Bearsite

  • avoid_the_noid [any, mirror/your pronouns]@hexbear.netEnglish
    6·
    23 hours ago

    Man, guess I’m getting older because I’m starting to no longer enjoy video games. Got cyberpunk/bg3/a slew of other games in my steam library and I don’t really find any of them enjoyable. Nothing more than about 1hr of playtime on any of them. I did really enjoy Look Outside and Fear and Hunger though, so maybe it’s just the type of game?

  • Goblinmancer [any]@hexbear.netEnglish
    5·
    1 day ago

    as someone from southeast asia in deadfire the rautaians read as imperial japan (resource starved colonizer doing “we are all one people” while doing war crimes) while the vailians read as the dutch but are italians cuz obsidian love italians or something.

  • Blockocheese [any]@hexbear.netEnglish
    3·
    23 hours ago

    Did 1 of the three things I wanted to today

    Couldn’t figure out parking and was worried about getting towed (my city is notorious for sketchy tow companies) so I missed the time for first thing, realized I was allergic to some of the food from the place I wanted to get takeout from so missed the second thing, did end up getting my prescription but im really not sure the pharmacist did compounding so im not allergic to it so I need to call him

    I feel embarrassed about missing the first thing but I’ll plan better next time blob-no-thoughts

  • came_apart_at_Kmart [he/him, comrade/them]@hexbear.netEnglish
    5·
    1 day ago

    i currently live in a quiet micropolitan downtown situation. literally zoned “downtown”, 25 mph streets, a bike lane that connects back to the cross town bike path, wide sidewalks with pedestrian cross walks everywhere, because it’s got a community center, a senior center, church, schools, a playground etc, and is about 80% residences with a few professional places. it is one of the major roads leading out of town. 100 yards away, running parallel is literally the bypass: gas stations, limited pedestrian infrastructure. it was purpose built to let people move quicker onto the next town and let the neighborhood become chill.

    97% of the cars that go by are totally normal. cruising at the reasonable 15-20mph with eyes peeled because there’s so much pedestrian activity, including really little kids with parents. i don’t gush over little kids, but seeing them learn to walk with their parents is basically adorable. i saw a little toddler at halloween that was dressed as a NASA space man and the parent was a big alien, and the way the kid walked/looked around in wonder it was like they were literally on the moon anyway. i could have died it was so cute. anyway, there’s that 1 in 30 driver that fucking bomb down the road at 35+, too fucking stupid to use the bypass and too reckless to give a fuck. i hate them more than anything.

    i was out there this morning, a goddamn saturday morning at 8am ish, just quickly moving a car to help an elderly person. the street is dead quiet except pedestrians and i look around before executing a quick 3 point turn to re-orient a parallel parked car. i spot the giant pickup 150 yards away and if he had been going the speed limit, i would have been out of his way before he got there, but the guy was fucking flying. and he was my least favorite genre of american: ancient old white dude with a fucking GIANT empty pickup truck that is in mint condition. he comes right up on me just as i am pulling out of the way and throws his hands up like he’s completely baffled by someone making a 3 point turn in a quiet, residential street with street parking. i’m generally passive as hell, but i couldn’t even help myself. i just instantly flipped him the fucking bird. i was so mad i was literally hoping he would take offense and do literally anything to escalate. i don’t like to make a thing of it, but i am 6’, 240 lbs of stacked shit and i would have loved to foreclose on both our futures at that moment. i fucking hate the people that fly down this road. if i could push a button and make them burn to death in their cars, i would tape the button down.

    he didn’t do shit of course and just scooted along because i believe he had made that gesture just as he was realizing i was a big oaf stuffed into a silly little vehicle, unlike the giant metal box protecting his frail and unstable form. i was so ready to say all kinds of unproductive shit. but he just left as i watched him in the rear view, tearing ass down the road and disappearing. still mad about it though, that someone could just push all my buttons like that and have me seeing red.

  • WhyEssEff [she/her]@hexbear.netEnglish
    2·
    22 hours ago

    looking into it after I got my shit obliterated, why the fuck did Pritzker increase the senior driving test age minimum to 79?

    “Study after study indicates that senior drivers are the most safe amongst us and there’s really no need for this onerous test to be administered when you are a senior,” said bill sponsor Rep. Jay Hoffman in a statement.

    Please show me these studies because I find this credulous at face value. The point is, as far as I am aware, to make sure they aren’t suffering age-related driving ability degradation. It’s a matter of risk, not general competence. Are they just allowing people well-past the dementia-risk age-threshold to dodge a fucking basic competence test?

    Long arm of the carhitler boomerreich. You will have your family annihilated by the 78-year-old who forgot which foot the brake pedal is nineteeneightyfour

  • LeeeroooyJeeenkiiins [none/use name]@hexbear.netEnglish
    4·
    1 day ago

    I kind of want to play the revived Heroes of Newerth because I played like 8000 hours of the original but I am resentful of having paid money for it, it going free to play, then getting cancelled

    I feel like kongor games owes me 20 bucks if they want me to play their game

  • WokePalpatine [he/him]@hexbear.netEnglish
    4·
    1 day ago

    Guys who watch Pseudo-Prof. Jiang posting on YouTube: “Mmmhm, really makes me think”

    “What are you thinking?”

    “Politics stuff. A lot of it”

  • PowerLurker [he/him, they/them]@hexbear.netEnglish
    4·
    1 day ago

    rip me away from this silly rabbit hole centered on how period accurate telegraphs would work for my D&D campaign so i am not late for work players do not notice or care about this shit but my brain won’t obey my commands please help me aaaaaaaaaaaaa oooaaaaaaauhhh