{{Short description|Species of rodent}} {{About|the species of rodent}} {{Use dmy dates|date=December 2025}} {{cs1 config|display-authors=6}} {{Speciesbox | name = Black rat | fossil_range = Holocene | image = House Rat David Raju.jpg | image_alt = | image_caption = Black rat in India | status = LC | status_system = IUCN3.1 | status_ref = <ref name="iucn status 19 November 2021">{{cite iucn |last1=Kryštufek |first1=B. |last2=Palomo |first2=L. |last3=Hutterer |first3=R. |last4=Mitsainas |first4=G. |last5=Yigit |first5=N. |date=2021 |title=''Rattus rattus'' |volume=2021 |article-number=e.T19360A192565917 |doi=10.2305/IUCN.UK.2021-1.RLTS.T19360A192565917.en |access-date=19 November 2021}}</ref> | genus = Rattus | species = rattus | authority = (Linnaeus, 1758) | synonyms = ''Mus rattus'' {{small|Linnaeus,&nbsp;1758}} | range_map = Black rat range map.png }}

The '''black rat''' ('''''Rattus rattus'''''), also known as the '''roof rat''', '''ship rat''', or '''house rat''', is a common long-tailed rodent of the stereotypical rat genus ''Rattus'', in the subfamily Murinae.<ref name="iucn status 19 November 2021" /> It is a generalist omnivore that can live on a wide variety of foods. It associates extensively with humans, and most populations are synanthropic.<ref name=":1" /> It likely originated in the Indian subcontinent, but is now found worldwide.<ref>{{Cite journal |last1=Baig |first1=M. |last2=Khan |first2=S. |last3=Eager |first3=H. |last4=Atkulwar |first4=A. |last5=Searle |first5=J. B. |date=2019 |title=Phylogeography of the black rat ''Rattus rattus'' in India and the implications for its dispersal history in Eurasia |journal=Biological Invasions |volume=21 |issue=2 |pages=417–433 |bibcode=2019BiInv..21..417B |doi=10.1007/s10530-018-1830-0 |s2cid=67790305}}</ref>

The black rat is black to light brown in colour with a lighter underside. It is a prominent pest to farmers because it feeds on a wide range of agricultural crops. It is sometimes kept as a pet, though most domestic rats are a subspecies of the brown rat.<ref name="afrma-history">{{cite web |url=http://afrma.org/rminfo4a.htm|title=The History of Fancy Rats|publisher=American Fancy Rat and Mouse Association|access-date=10 November 2008|archive-date=30 May 2013|archive-url=https://web.archive.org/web/20130530074258/http://www.afrma.org/rminfo4a.htm|url-status=dead}}</ref> In parts of India, it is considered sacred and respected, notably at the Karni Mata Temple in Deshnoke.<ref>{{Cite journal |last=Trembley |first=Kyle J. |date=2022-04-18 |title=Jatikaran: Caste, Rats, and the control of space at the Karni Mata Mandir |url=http://journals.sagepub.com/doi/10.1177/25148486221094132 |journal=Environment and Planning E: Nature and Space |volume=6 |issue=2 |language=en |pages=717–735 |doi=10.1177/25148486221094132 |s2cid=248248576 |issn=2514-8486|url-access=subscription }}</ref>

==Taxonomy== {{Expand section|date=February 2026}} ''Mus rattus'' was the scientific name proposed by Carl Linnaeus in 1758 for the black rat.<ref>{{cite book |last=Linnæus |first=C. |title=Caroli Linnæi Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I |publisher=Laurentius Salvius |year=1758 |edition=Decima, reformata |location=Holmiae |page=61 |language=la |chapter=''Mus rattus'' |chapter-url=https://archive.org/stream/mobot31753000798865#page/61/mode/2up}}</ref>

==Description== {{expand section|date=January 2026}} thumb|Closeup of the head of a black rat|alt=Rat seen from above cropped to show only the head and a forelimb thumb|alt=Rat skull|Skull of a black rat [[File:Comparison Black Rat Brown Rat EN.svg|thumb|Comparison of physique with a brown rat (''Rattus norvegicus'')|alt=Diagram showing differences between the physical features of black and brown rats]] [[File:Black Rat skeleton.jpg|thumb|Black rat skeleton at the Museum of Osteology|alt=Black rat skeleton]] A typical adult black rat is {{cvt|12.75|to|18.25|cm}} long, not including a {{cvt|15|to|22|cm}} tail, and weighs {{cvt|75|to|230|g}}, depending on the subspecies.<ref>{{Cite web |title=Black rat, House Rat, Roof Rat, Ship Rat (''Rattus rattus'') |url=http://www.waza.org/en/zoo/visit-the-zoo/rodents-and-hares/rattus-rattus |archive-url=https://web.archive.org/web/20161019212834/http://www.waza.org/en/zoo/visit-the-zoo/rodents-and-hares/rattus-rattus |archive-date=19 October 2016 |access-date=19 October 2016 |website=WAZA.org}}</ref><ref name="adw">{{cite web |last=Gillespie |first=H. |date=2004 |title=''Rattus rattus'' – house rat |url=http://animaldiversity.org/accounts/Rattus_rattus/ |website=Animal Diversity Web}}</ref><ref>{{cite book |author1=Schwartz, C. W. |url=https://books.google.com/books?id=uEWl0ZM6DfUC |title=The Wild Mammals of Missouri |author2=Schwartz, E. R. |publisher=University of Missouri Press |year=2001 |isbn=978-0-8262-1359-4}}</ref><ref>{{cite book |author=Engels, D. W. |title=Classical Cats: The Rise and Fall of the Sacred Cat |publisher=Routledge |year=1999 |isbn=978-0-415-21251-9 |location=London and New York |pages=1–17 |chapter=Rats |chapter-url=https://books.google.com/books?id=VkqtGl7VN44C&pg=PA16}}</ref> Despite its name, the black rat exhibits several colour forms. It is usually black to light brown in colour with a lighter underside. In England during the 1920s, several variations were bred and shown alongside domesticated brown rats. This included an unusual green-tinted variety.<ref>{{cite book |author=Alderton, D. |title=Rodents of the World |publisher=Diane Publishing Company |year=1996 |isbn=0-8160-3229-7}}</ref>

The species has three colour variants: *Roof rat – between greyish black merging into slate grey to all-black *Alexandrine rat – agouti and grey through slate grey *Fruit rat – agouti and pure white.<ref>{{Cite journal |last=Kambe |first=Yoshikazu |last2=Tanikawa |first2=Tsutomu |last3=Matsumoto |first3=Yasuharu |last4=Tomozawa |first4=Morihiko |last5=Aplin |first5=Ken P. |last6=Suzuki |first6=Hitoshi |date=2011-08-01 |title=Origin of Agouti-Melanistic Polymorphism in Wild Black Rats (Rattus rattus) Inferred from Mc1r Gene Sequences |url=https://bioone.org/journals/zoological-science/volume-28/issue-8/zsj.28.560/Origin-of-Agouti-Melanistic-Polymorphism-in-Wild-Black-Rats-Rattus/10.2108/zsj.28.560.full |journal=Zoological Science |volume=28 |issue=8 |pages=560 |doi=10.2108/zsj.28.560 |issn=0289-0003|url-access=subscription }}</ref>

==Origin== The black rat was present in prehistoric Europe and in the Levant during postglacial periods.<ref name="Rackham">{{cite journal |author=Rackham, J. |year=1979 |title=''Rattus rattus'': The introduction of the black rat into Britain |journal=Antiquity |volume=53 |issue=208 |pages=112–120 |doi=10.1017/s0003598x00042319 |pmid=11620121 |s2cid=46387899}}</ref> The black rat in the Mediterranean region differs genetically from its South Asian ancestor by having 38 instead of 42 chromosomes.<ref>{{cite journal |last1=Yosida |first1=T. H. |last2=Tsuchiya |first2=K. |last3=Moriwaki |first3=K. |date=1971 |title=Karyotypic differences of black rats, ''Rattus rattus'', collected in various localities of East and Southeast Asia and Oceania |journal=Chromosoma |volume=33 |issue=3 |pages=252–267 |doi=10.1007/BF00284943 |pmid=5088494 |s2cid=12454478}}</ref> Its closest relative is the Asian house rat (''R. tanezumi'') from Southeast Asia. The two diverged about 120,000 years ago in southwestern Asia. It is unclear how the rat made its way to Europe due to insufficient data, although a land route seems more likely based on the distribution of European haplogroup "A". The black rat spread throughout Europe with the Roman conquest, but declined around the 6th century, possibly due to collapse of the Roman grain trade, climate cooling, or the Justinianic Plague. ''R. rattus'' specimens have been found dating back to 800 BCE in Britain, although it is unclear how they migrated there.<ref>{{cite journal |last=Rackham |first=J. |date=1979 |title=Rackham J. Rattus rattus: the introduction of the black rat into Britain |journal=Antiquity |volume=53 |pages=112–120 |doi=10.1017/S0003598X00042319 |pmid=11620121}}</ref> A genetically different rat population of haplogroup A replaced the Roman population in the medieval times in Europe.<ref>{{cite journal |last1=Yu |first1=He |last2=Jamieson |first2=Alexandra |last3=Hulme-Beaman |first3=A. |last4=Conroy |first4=C. J. |last5=Knight |first5=B. |last6=Speller |first6=C. |last7=Al-Jarah |first7=H. |last8=Eager |first8=H. |last9=Trinks |first9=A. |last10=Adikari |first10=G. |last11=Baron |first11=H. |last12=Böhlendorf-Arslan |first12=B. |last13=Bohingamuwa |first13=W. |last14=Crowther |first14=A. |last15=Cucchi |first15=T. |date=2022 |title=Palaeogenomic analysis of black rat (''Rattus rattus'') reveals multiple European introductions associated with human economic history |journal=Nature Communications |volume=13 |issue=1 |page=2399 |bibcode=2022NatCo..13.2399Y |doi=10.1038/s41467-022-30009-z |pmc=9064997 |pmid=35504912 |last16=Esser |first16=K. |last17=Fleisher |first17=J. |last18=Gidney |first18=L. |last19=Gladilina |first19=E. |last20=Gol'din |first20=Pavel |last21=Goodman |first21=S. M. |last22=Hamilton-Dyer |first22=S. |last23=Helm |first23=R. |last24=Hillman |first24=J. C. |last25=Kallala |first25=N. |last26=Kivikero |first26=H. |last27=Kovács |first27=Zsófia E. |last28=Kunst |first28=G. K. |last29=Kyselý |first29=R. |last30=Linderholm |first30=A. |last31=Maraoui-Telmini |first31=B. |last32=Marković |first32=N. |last33=Morales-Muñiz |first33=A. |last34=Nabais |first34=M. |last35=O'Connor |first35=T. |last36=Oueslati |first36=T. |last37=Quintana Morales |first37=E. M. |last38=Pasda |first38=K. |last39=Perera |first39=J. |last40=Perera |first40=Nimal |last41=Radbauer |first41=S. |last42=Ramon |first42=J. |last43=Rannamäe |first43=E. |last44=Sanmartí Grego |first44=J. |last45=Treasure |first45=E. |last46=Valenzuela-Lamas |first46=S. |last47=van der Jagt |first47=I. |last48=Van Neer |first48=W. |last49=Vigne |first49=J.-D. |last50=Walker |first50=T. |last51=Wynne-Jones |first51=S. |last52=Zeiler |first52=J. |last53=Dobney |first53=K. |last54=Boivin |first54=N. |last55=Searle |first55=J. B. |last56=Krause-Kyora |first56=B. |last57=Krause |first57=J. |last58=Larson |first58=G. |last59=Orton |first59=D.}}</ref>

It is a resilient vector for many diseases because of its ability to hold so many infectious bacteria in its blood. It was formerly thought to have played a primary role in spreading bacteria contained in fleas on its body, such as the plague bacterium (''Yersinia pestis'') which is responsible for the Plague of Justinian and the Black Death.<ref name="McCormick">{{cite journal |author=McCormick, M. |year=2003 |title=Rats, communications, and plague: Toward an ecological history |url=http://dash.harvard.edu/bitstream/handle/1/3208221/McCormick_RatsPlague.pdf |journal=Journal of Interdisciplinary History |volume=34 |issue=1 |pages=1–25 |doi=10.1162/002219503322645439 |s2cid=128567627}}</ref> However, recent studies have called this theory into question and instead posit humans themselves as the vector, as the movements of the epidemics and the black rat populations do not show historical or geographical correspondence.<ref>{{cite web |last=Little |first=Becky |date=28 May 2025 |orig-date=17 January 2018 |title=Rats Didn't Spread the Black Death—It Was Humans |url=https://www.history.com/news/rats-didnt-spread-the-black-death-it-was-humans |website=history.com}}</ref><ref>{{Cite news |date=15 January 2018 |title=Black Death 'spread by humans not rats' |url=https://www.bbc.com/news/science-environment-42690577 |access-date=6 March 2023 |work=BBC News |language=en-GB}}</ref> A study published in 2015 indicates that other Asiatic rodents served as plague reservoirs, from which infections spread as far west as Europe via trade routes, both overland and maritime. Although the black rat was certainly a plague vector in European ports, the spread of the plague beyond areas colonized by rats suggests that the plague was also circulated by humans after reaching Europe.<ref>{{cite journal |last1=Schmid, B.V. |last2=Büntgen, U. |last3=Easterday, W.R. |last4=Ginzler, C. |last5=Walløe, L. |last6=Bramanti, B. |last7=Stenseth, N.C. |date=2015 |title=Climate-driven introduction of the Black Death and successive plague reintroductions into Europe |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=112 |issue=10 |pages=3020–3025 |bibcode=2015PNAS..112.3020S |doi=10.1073/pnas.1412887112 |pmc=4364181 |pmid=25713390 |doi-access=free}}</ref>

==Distribution and habitat== The black rat originated in India and Southeast Asia, and spread to the Near East and Egypt, and then throughout the Roman Empire, reaching Great Britain as early as the 1st century AD.<ref>{{cite book |last=Engels |first=Donald W. |url=https://books.google.com/books?id=VkqtGl7VN44C&pg=PA111 |title=Classical Cats: The Rise and Fall of the Sacred Cat |publisher=Routledge |year=1999 |isbn=978-0-415-21251-9 |page=111}}</ref> Europeans subsequently spread it throughout the world. The black rat is again largely confined to warmer areas, having been supplanted by the brown rat (''Rattus norvegicus'') in cooler regions and urban areas. In addition to the brown rat being larger and more aggressive, the change from wooden structures and thatched roofs to bricked and tiled buildings favoured 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.<ref>{{cite web |last=Rowland |first=Teisha |date=4 December 2009 |title=Ancient Origins of Pet Rats |url=http://www.independent.com/news/2009/dec/04/ancient-origins-modern-pet-rats/?print |archive-url=https://web.archive.org/web/20150924200319/http://www.independent.com/news/2009/dec/04/ancient-origins-modern-pet-rats/?print |archive-date=24 September 2015 |website=Santa Barbara Independent}}</ref>

Black rat populations can increase exponentially under certain circumstances, perhaps having to do with the timing of the fruiting of the bamboo plant, and cause devastation to the plantings of subsistence farmers; this phenomenon is known as ''mautam'' in parts of India.<ref>{{cite episode |title=Nova: Rat Attack |series=Nova |network=PBS |date=7 April 2010}}</ref>

Black rats are thought to have arrived in Australia with the First Fleet, and subsequently spread to many coastal regions in the country.<ref>{{cite web |last=Evans |first=Ondine |date=1 April 2010 |title=Animal Species: Black Rat |url=https://australian.museum/learn/animals/mammals/black-rat/ |access-date=31 December 2010 |work=Australian Museum website |publisher=Australian Museum |location=Sydney, Australia}}</ref>

Black rats adapt to a wide range of habitats. In urban areas they are found around warehouses, residential buildings, and other human settlements. They are also found in agricultural areas, such as in barns and crop fields.<ref name=":1">{{cite web |title=Black Rats |url=https://www.depts.ttu.edu/nsrl/mammals-of-texas-online-edition/Accounts_Introduced_Rodentia/Rattus_rattus.php |access-date=15 February 2024 |website=Natural Science Research Laboratory |publisher=Texas Tech University |department=Mammals of Texas: Online Edition}}</ref> In urban areas, they prefer to live in dry upper levels of buildings, so they are commonly found in wall cavities and false ceilings. In the wild, black rats live in cliffs, rocks, the ground, and trees.<ref>{{cite web |date=22 November 2022 |title=Rattus Rattus |url=https://www.pestsolutions.co.uk/pest-library/rodent-pest-species/black-rats-rattus-rattus |access-date=15 February 2024 |website=Pest Solutions}}</ref> They are great climbers and prefer to live in palms and trees, such as pine trees. Their nests are typically spherical and made of shredded material, including sticks, leaves, other vegetation and cloth. In the absence of palms or trees, they can burrow into the ground.<ref name="black">{{cite web |author=Bennet, Stuart M. |title=The Black Rat (''Rattus Rattus'') |url=http://www.the-piedpiper.co.uk/th1b.htm |access-date=22 April 2011 |work=The Pied Piper}}</ref> Black rats are also found around fences, ponds, riverbanks, streams, and reservoirs.<ref name="roof">{{cite web |author=Marsh, Rex E. |year=1994 |title=Roof Rats |url=http://icwdm.org/handbook/rodents/RoofRats.asp |archive-url=https://web.archive.org/web/20110521025949/http://icwdm.org/handbook/rodents/RoofRats.asp |archive-date=21 May 2011 |access-date=22 April 2011 |work=Internet Center for Wildlife Damage Management |publisher=Prevention and Control of Wildlife Damage}}</ref>

==Behaviour and ecology== The black rat has a wide home range, typically foraging in a home range of {{cvt|0.28|-|1.2|ha}}. Its home range is highly dependent on its gender, as male rats range can be up to thrice that of female rats.<ref>{{cite journal |last1=Whisson |first1=D. |last2=Quinn |first2=J. |last3=Collins |first3=K. |date=2007 |title=Home range and movements of Roof Rats (''Rattus rattus'') in an old-growth riparian forest, Californiac |journal=Journal of Mammalogy |volume=88 |issue=3 |pages=589–594 |bibcode=2007JMamm..88..589W |doi=10.1644/06-MAMM-A-239R1.1}}</ref> Its home range also differs depending on the type of forest; home ranges in the southern beech forests of the South Island, New Zealand appear to be much larger than the non-beech forests of the North Island. Due to the limited number of rats that are studied in home range studies, the estimated sizes of rat home ranges in different rat demographic groups are inconclusive.<ref name="Beech">{{cite journal |last1=Pryde |first1=M. |last2=Dilks |first2=P. |last3=Fraser |first3=I. |date=2005 |title=The home range of ship rats (''Rattus rattus'') in beech forest in the Eglinton Valley, Fiordland, New Zealand: A pilot study |journal=New Zealand Journal of Zoology |volume=32 |issue=3 |pages=139–142 |doi=10.1080/03014223.2005.9518406}}</ref>

===Social behaviour=== The black rat is generally territorial, although the territory is typically a small subset of the full range. Female black rats have no hierarchy, and are generally more aggressive, while male rats tend to flee when attacked unless females are present.<ref>{{cite book |last=Barnett |first=S. A. |url=https://www.taylorfrancis.com/books/mono/10.4324/9781315134468/rat-barnett |title=The rat: A Study in Behaviour |date=2017 |isbn=978-0-7081-0108-7 |page=129 |doi=10.4324/9781315134468}}</ref> Like its relative ''R. norvegicus'', ''R. rattus'' often huddle in groups.<ref name="SocialBehaviour">{{cite journal |last=Barnett |first=S. A. |date=1958 |title=An analysis of social behaviour in wild rats |journal=The Zoological Society of London |volume=130 |pages=130–132 |doi=10.1111/j.1096-3642.1958.tb00565.x}}</ref> Rats are at their most aggressive when they have just reached adulthood, but do not tend to lose status as they grow older, and younger rats are often singled out as enemies by older females. Older females and male rats of high status rarely fight among themselves, although they are occasionally fought by younger rats.<ref name="dnb">{{cite web |last=Ewer |first=R. F. |title=The Biology and Behaviour of a Free-Living Population of Black Rats (Rattus rattus) |url=https://d-nb.info/115688330X/34}}</ref> Although ''rattus'' and ''norvegicus'' can coexist in the same habitat, ''R. rattus'' will typically attack any ''norvegicus'' that enter an established colony.{{r |SocialBehaviour |p=134-135}} [[File:20191212 Szczury w Świątyni Karni Maty w Deśnok 1052 8152 DxO.jpg|thumb|Thousands of black rats live at the Karni Mata Temple, the "Temple of Rats"]] Rats may mark their territory by rubbing themselves against trees, and typically prefer to mark areas that are the least secure from other rats.{{r |dnb |p=154-155}} Scents produced in their preputial gland are also used to identify rats to the opposite sex during mating.<ref>{{cite journal |last1=Bala |first1=Bindu |last2=Kaur Babbar |first2=Bhupinder |date=2024 |title=Behavioural responses and characterization of preputial gland extract of black rat, Rattus rattus |url=https://link.springer.com/article/10.1007/s11756-024-01685-7 |journal=Biologia |volume=79 |issue=7 |pages=2079–2093 |bibcode=2024Biolg..79.2079B |doi=10.1007/s11756-024-01685-7|url-access=subscription }}</ref>

===Mating and reproduction=== Black rats typically breed year-round, and females can produce up to 5 litters in one season.<ref name="ArizonaRat">{{cite web |date=July 2018 |title=Roof Rats: Identification, Ecology, and Signs |url=https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1775-2018.pdf}}</ref> In populations where most rats are closely related, rats may leave the colony as they reach sexual maturity in order to avoid inbreeding.<ref name="RatBehavioral">{{cite journal|title=Behavioral Aspects of Rodent Population Biology1|journal=American Zoologist|url=https://academic.oup.com/icb/article-abstract/27/3/953/210890|doi=10.1093/icb/27.3.953|first=Lee|last=Drickamer|url-access=subscription}}</ref> During copulation, male rats seldom mount females for more than one second, but can continue to mount a female repeatedly for up to ten minutes.{{r|dnb|p=33}} Female rats' gestation period can range from 12 to 29 days.{{r|dnb|p=35}} Black rats typically live for about one year in the wild and up to four years in captivity.<ref name="adw" />

===Diet and foraging=== [[File:Rattus rattus 01.JPG|thumb|Taxidermy of a black rat eating grain at the State Museum of Natural History Karlsruhe|alt=A taxidermied rat sitting on a sack of grain]] The black rat is considered to be an omnivore and eats a wide range of foods, including seeds, fruit, stems, leaves, fungi, and a variety of invertebrates and vertebrates. It is a generalist, and thus not very specific in its food preferences, which is indicated by its tendency to feed on any meal provided for cows, swine, chickens, cats and dogs.<ref name=roof/> It eats about {{cvt|15|g}} per day and drinks about {{cvt|15|ml}} per day.<ref name=black/> Its diet is high in water content.<ref name=roof/> It feeds on birds and insects, and also on a variety of agricultural-based crops, such as cereals, sugar cane, coconuts, cocoa, oranges, and coffee beans.<ref name="rattus">{{cite web |date=22 November 2022 |title=''Rattus rattus'' – Roof rat |url=https://www.pestsolutions.co.uk/pest-library/rodent-pest-species/black-rats-rattus-rattus |access-date=15 February 2024 |work=Pest Solutions}}</ref>

The black rat displays flexibility in its foraging behaviour. It is a predatory species and adapts to different micro-habitats. It often meets and forages together in close proximity within and between sexes.<ref name=Dowding/> It tends to forage after sunset. If the food cannot be eaten quickly, it searches for a place to carry and hoard to eat at a later time.<ref name=roof/> Although it eats a broad range of foods, it is a highly selective feeder; only a restricted selection of the foods is dominating.<ref name="Clark">{{cite journal |author=Clark, D. A. |year=1982 |title=Foraging behavior of vertebrate omnivore (''Rattus rattus''): Meal structure, sampling, and diet breadth |journal=Ecology |volume=63 |issue=3 |pages=763–772 |bibcode=1982Ecol...63..763C |doi=10.2307/1936797 |jstor=1936797}}</ref> When offered a wide diversity of foods, it eats only a small sample of each. This allows it to monitor the quality of foods that are present year round, such as leaves, as well as seasonal foods, such as herbs and insects. This method of operating on a set of foraging standards ultimately determines the final composition of its meals. Also, by sampling the available food in an area, it maintains a dynamic food supply, balances its nutrient intake, and avoids intoxication by secondary compounds.<ref name=Clark/>

===Nesting behaviour=== Through the usage of tracking devices such as radio transmitters, rats have been found to occupy dens located in trees, as well as on the ground. In Puketi Forest in the Northland Region of New Zealand, rats have been found to form dens together. Rats appear to den and forage in separate areas in their home range depending on the availability of food resources.<ref name="Dowding">{{cite journal |last1=Dowding |first1=J.E. |last2=Murphy |first2=E.C. |year=1994 |title=Ecology of Ship Rats (''Rattus rattus'') in a Kauri (''Agathis australis'') Forest in Northland, New Zealand |url=https://newzealandecology.org/nzje/1947.pdf |journal=New Zealand Journal of Ecology |volume=18 |issue=1 |pages=19–28}}</ref> Research shows that, in New South Wales, the black rat prefers to inhabit lower leaf litter of forest habitat. There is also an apparent correlation between the canopy height and logs and the presence of black rats. This correlation may be a result of the distribution of the abundance of prey as well as available refuges for rats to avoid predators. As found in North Head, New South Wales, there is positive correlation between rat abundance, leaf litter cover, canopy height, and litter depth. All other habitat variables showed little to no correlation.<ref name="Cox">{{cite journal |author1=Cox, M.P.G. |author2=Dickman, C.R. |author3=Cox, W.G. |name-list-style=amp |year=2000 |title=Use of habitat by the black rat (''Rattus rattus'') at North Head, New South Wales: an observational and experimental study |journal=Austral Ecology |volume=25 |issue=4 |pages=375–385 |bibcode=2000AusEc..25..375C |doi=10.1046/j.1442-9993.2000.01050.x}}</ref> Unlike brown rats, black rats have a tendency to nest inside trees or the upper floors of a house,.<ref>{{cite web |date=July 2018 |title=Roof Rats: Identification, Ecology, and Signs |url=https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1775-2018.pdf}}</ref>

===Diseases=== Black rats (or their ectoparasites<ref>{{cite journal |last1=Hafidzi |first1=M.N. |last2=Zakry |first2=F.A.A. |last3=Saadiah |first3=A. |year=2007 |title=Ectoparasites of ''Rattus'' sp. from Petaling Jaya, Selangor, Malaysia |journal=Pertanika Journal of Tropical Agricultural Science |volume=30 |issue=1 |pages=11–16}}</ref>) can carry a number of pathogens,<ref>{{cite journal |author=Meerburg, B.G. |author2=Singleton, G.R. |author3=Kijlstra A. |year=2009 |title=Rodent-borne diseases and their risks for public health |journal=Crit Rev Microbiology |volume=35 |issue=3 |pages=221–270 |doi=10.1080/10408410902989837 |pmid=19548807 |s2cid=205694138}}</ref> of which bubonic plague (via the Oriental rat flea), typhus, Weil's disease, toxoplasmosis and trichinosis are the best known. It has been hypothesized that the displacement of black rats by brown rats led to the decline of the Black Death.<ref>Last, John M. [http://www.enotes.com/public-health-encyclopedia/black-death "Black Death"], ''Encyclopedia of Public Health'', eNotes website. Retrieved 31 December 2010.</ref><ref>Barnes, Ethne (2007). ''Diseases and Human Evolution'', University of New Mexico Press, {{ISBN|978-0-8263-3066-6}}, [https://books.google.com/books?id=wnlB7EMtqFYC&pg=PA247 p. 247].</ref> This theory has, however, been deprecated, as the dates of these displacements do not match the increases and decreases in plague outbreaks.<ref>Bollet, Alfred J. (2004). ''Plagues & Poxes: The Impact of Human History on Epidemic Disease'', Demos Medical Publishing, 2004, {{ISBN|978-1-888799-79-8}}, [https://books.google.com/books?id=bHIj5PJdZbkC&pg=PA23 p. 23]</ref><ref>Carrick, Tracy Hamler; Carrick, Nancy and Finsen, Lawrence (1997). ''The Persuasive Pen: An Integrated Approach to Reasoning and Writing'', Jones and Bartlett Learning, 1997, {{ISBN|978-0-7637-0234-2}}, [https://books.google.com/books?id=6miPAUtQUO4C&pg=PA162 p. 162].</ref><ref>Hays, J. N. (2005). ''Epidemics and Pandemics: Their Impacts on Human History'', ABC-CLIO, {{ISBN|978-1-85109-658-9}}, [https://archive.org/details/epidemicspandemi0000hays/page/64 p. 64].</ref>

====Plague==== Black rats are the main transmitter of bubonic plague, or ''Yersinia pestis'', which they spread indirectly through the fleas they carry.<ref name="FleaRat">{{cite journal |last=Liston |first=W. G. |date=1905 |title=Plague, Rats, and Fleas |journal=Bombay Natural History Society |volume=40 |issue=2 |pages=43–49 |pmc=5163050 |pmid=29004844}}</ref> Although other animals such as coyotes, bobcats, and rabbits can serve as plague reservoirs, the flea species ''Xenopsylla cheopis'' commonly carried by ''R. rattus'' is one of the most effective spreaders.<ref>{{cite journal |last=Ell |first=Stephen R. |date=1980 |title=Interhuman Transmission of Medieval Plague |url=https://www.jstor.org/stable/44441288 |journal=Bulletin of the History of Medicine |volume=54 |issue=4 |pages=497–510 |jstor=44441288 |pmid=7004542 }}</ref> However, archaeological evidence indicates that ''R. rattus'' might not have been present during the Black Death in England, suggesting that the plague was spread by another species.<ref>{{cite journal |last=Davis |first=David E. |date=1986 |title=The Scarcity of Rats and the Black Death: An Ecological History |url=https://www.jstor.org/stable/204499 |journal=Journal of Interdisciplinary History |volume=16 |issue=3 |pages=455–470 |doi=10.2307/204499 |jstor=204499|url-access=subscription }}</ref> Although ''R. rattus'' populations often die out after a plague, causing transmission to cease, rats that survive the plague can serve as reservoirs for the disease, as well as transmitting it from wild reservoir populations to human settlements.<ref>{{cite journal |last1=Andrianaivoarimanana |first1=Voahangy |last2=Telfer |first2=Sandra |last3=Rajerison |first3=Minoarisoa |last4=Ranjalahy |first4=Michel A. |last5=Andriamiarimanana |first5=Fehivola |last6=Rahaingosoamamitiana |first6=Corinne |last7=Rahalison |first7=Lila |last8=Jambou |first8=Ronan |date=2012 |title=Immune Responses to Plague Infection in Wild ''Rattus rattus'', in Madagascar: A Role in Foci Persistence? |journal=PLOS ONE |volume=7 |issue=6 |bibcode=2012PLoSO...738630A |doi=10.1371/journal.pone.0038630 |doi-access=free |article-number=e38630|pmid=22719908 |pmc=3377696 }}</ref> Rats in regions where plague is present may also develop immunity, allowing rats and their associated fleas to survive longer than in other regions.<ref>{{cite journal |last1=Andrianaivoarimanana |first1=Voahangy |last2=Rajerison |first2=Minoarisoa |last3=Jambou |first3=Ronan |date=2018 |title=Exposure to ''Yersinia pestis'' increases resistance to plague in black rats and modulates transmission in Madagascar |url=https://link.springer.com/content/pdf/10.1186/s13104-018-3984-3.pdf |journal=BMC Research Notes |volume=11 |issue=1 |doi=10.1186/s13104-018-3984-3 |pmc=6295079 |pmid=30551741 |doi-access=free |article-number=898}}</ref> Black rats' transmission of the Black Death in Europe was likely halted by a change in the ''Yersinia pestis'' bacterium that produced a milder version, inoculating rat populations against the plague.<ref>{{cite journal |last=McEvedy |first=Colin |date=1988 |title=The Bubonic Plague |url=https://www.jstor.org/stable/24988987 |journal=Scientific American |volume=258 |issue=2 |pages=118–123 |bibcode=1988SciAm.258b.118M |doi=10.1038/scientificamerican0288-118 |jstor=24988987 |pmid=3055286}}</ref>

Rats serve as outstanding vectors for transmittance of diseases because they can carry bacteria and viruses in their systems. A number of bacterial diseases are common to rats, and these include ''Streptococcus pneumoniae'', ''Corynebacterium kutsheri,'' ''Bacillus piliformis'', ''Pasteurella pneumotropica'', and ''Streptobacillus moniliformis'', to name a few. As well as carrying zoonotic infections, ''R. rattus'' is also capable of transmitting diseases to native rat species, causing their decline when ''rattus'' is introduced.<ref name="RatEco"/> In some cases, these diseases are incurable.<ref name="bacterial">{{cite web |author=Boschert, K. |date=1991 |title=Rat Bacterial Diseases |url=http://netvet.wustl.edu/species/rats/ratbact.txt |archive-url=https://web.archive.org/web/19961018162831/http://netvet.wustl.edu/species/rats/ratbact.txt |archive-date=18 October 1996 |access-date=22 April 2011 |work=Net Vet and the Electronic Zoo}}</ref> In addition to transmitting bacterial infections, black rats can also cary parasites such as ''Calodium'', and protozoas including ''Toxoplasma gondii'', many of which can be transmitted to humans.<ref name=":0">{{Cite journal |last1=Banks |first1=Peter B. |last2=Hughes |first2=Nelika K. |date=2012-02-27 |title=A review of the evidence for potential impacts of black rats (Rattus rattus) on wildlife and humans in Australia |url=https://connectsci.au/wr/article/39/1/78/40414/A-review-of-the-evidence-for-potential-impacts-of |journal=Wildlife Research |language=en |volume=39 |issue=1 |pages=78–88 |doi=10.1071/WR11086 |bibcode=2012WildR..39...78B |issn=1035-3712|url-access=subscription }}</ref><ref>{{cite journal |last1=Huffhammer |first1=Anne Karin |last2=Walloe |first2=Lars |title=Rats cannot have been intermediate hosts for Yersinia pestis during medieval plague epidemics in Northern Europe |url=https://www.uib.no/sites/w3.uib.no/files/attachments/rats-plague-arch-akh-lw.pdf |journal=Journal of Archaeological Science}}</ref>

===Predators=== The black rat is prey to cats and owls in domestic settings. In less urban settings, rats are preyed on by weasels, foxes and coyotes. These predators have little effect on the control of the black rat population because black rats are agile and fast climbers. In addition to agility, the black rat also uses its keen sense of hearing to detect danger and quickly evade mammalian and avian predators.<ref name=roof/>

==As an invasive species==

===Damage caused=== After ''Rattus rattus'' was introduced into the northern islands of New Zealand, they fed on the seedlings, adversely affecting the ecology of the islands. ''R. rattus'' is known to destroy the nests of native birds, causing up to 96% of total nest predations.<ref name=":0" /> When consuming these seabirds and seabird eggs, these rats reduce the pH of the soil. This harms plant species by reducing nutrient availability in soil, thus decreasing the probability of seed germination. For example, research conducted by Hoffman et al. indicates a large impact on 16 indigenous plant species directly preyed on by ''R. rattus''. These plants displayed a negative correlation in germination and growth in the presence of black rats.<ref name="Grant-Hoffman">{{cite journal |author1=Grant-Hoffman, MN |author2=Mulder, CP |author3=Belingham, PJ |year=2009 |title=Invasive Rats Alter Woody Seedling Composition on Seabird-dominated Islands in New Zealand |journal=Oecologia |volume=163 |issue=2 |pages=449–60 |doi=10.1007/s00442-009-1523-6 |issn=1442-9993 |pmid=20033216 |s2cid=25286223}}</ref> Rats prefer to forage in forest habitats. In the Ogasawara islands, they prey on the indigenous snails and seedlings. Snails that inhabit the leaf litter of these islands showed a significant decline in population on the introduction of ''Rattus rattus''. The black rat shows a preference for snails with larger shells (greater than 10&nbsp;mm), and this led to a great decline in the population of snails with larger shells. A lack of prey refuges makes it more difficult for the snail to avoid the rat.<ref name="Chiba">{{cite journal |author=Chiba, S. |year=2010 |title=Invasive Rats Alter Assemblage Characteristics of Land Snails in the Ogasawara Islands |journal=Biological Conservation |volume=143 |issue=6 |pages=1558–63 |bibcode=2010BCons.143.1558C |doi=10.1016/j.biocon.2010.03.040}}</ref>

===Complex pest=== The black rat is a complex pest, defined as one that influences the environment in both harmful and beneficial ways. In many cases, after the black rat is introduced into a new area, the population size of some native species declines or goes extinct. This is because the black rat is a good generalist with a wide dietary niche and a preference for complex habitats; this causes strong competition for resources among small animals.<ref name="RatEco">{{cite journal |last1=Banks |first1=Peter |last2=Smith |first2=Helen |date=2015 |title=The ecological impacts of commensal species: black rats, Rattus rattus, at the urban–bushland interface |url=https://www.researchgate.net/publication/280291644 |journal=Wildlife Research |volume=42 |issue=2 |pages=86–97 |bibcode=2015WildR..42...86B |doi=10.1071/WR15048}}</ref> This has led to the black rat completely displacing many native species in Madagascar, the Galapagos, and the Florida Keys. In a study by Stokes ''et al.'', habitats suitable for the native bush rat, ''Rattus fuscipes'', of Australia are often invaded by the black rat and are eventually occupied by only the black rat. When the abundances of these two rat species were compared in different micro-habitats, both were found to be affected by micro-habitat disturbances, but the black rat was most abundant in areas of high disturbance; this indicates it has a better dispersal ability.<ref name="Vernes">{{cite journal |author1=Vernes, K |author2=Mcgrath, K |year=2009 |title=Are Introduced Black Rats (''Rattus rattus'') a Functional Replacement for Mycophagous Native Rodents in Fragmented Forests? |journal=Fungal Ecology |volume=2 |issue=3 |pages=145–48 |bibcode=2009FunE....2..145V |doi=10.1016/j.funeco.2009.03.001}}</ref>

Despite the black rat's tendency to displace native species, it can also aid in increasing species population numbers and maintaining species diversity. The bush rat, a common vector for spore dispersal of truffles, has been extirpated from many micro-habitats of Australia. In the absence of a vector, the diversity of truffle species would be expected to decline. In a study in New South Wales, Australia it was found that, although the bush rat consumes a diversity of truffle species, the black rat consumes as much of the diverse fungi as the natives and is an effective vector for spore dispersal. Since the black rat now occupies many of the micro-habitats that were previously inhabited by the bush rat, the black rat plays an important ecological role in the dispersal of fungal spores. By eradicating the black rat populations in Australia, the diversity of fungi would decline, potentially doing more harm than good.<ref name=Vernes/>

===Control methods=== Large-scale rat control programs have been taken to maintain a steady level of the invasive predators in order to conserve the native species in New Zealand such as kokako and mohua.<ref name="Pryde">{{cite journal |author1=Pryde, M. |author2=Dilks, P. |author3=Fraser, I. |year=2005 |title=The home range of ship rats (''Rattus rattus'') in beech forest in the Eglinton Valley, Fiordland, New Zealand: a pilot study |journal=New Zealand Journal of Zoology |volume=32 |issue=3 |pages=139–142 |doi=10.1080/03014223.2005.9518406 |s2cid=84513492}}</ref> Pesticides, such as pindone and 1080 (sodium fluoroacetate), are commonly distributed via aerial spray by helicopter as a method of mass control on islands infested with invasive rat populations. Bait, such as brodifacoum, is also used along with coloured dyes (used to deter birds from eating the baits) in order to kill and identify rats for experimental and tracking purposes. Another method to track rats is the use of wired cage traps, which are used along with bait, such as rolled oats and peanut butter, to tag and track rats to determine population sizes through methods like mark-recapture and radio-tracking.<ref name=Dowding/> Tracking tunnels (coreflute tunnels containing an inked card) are also commonly used monitoring devices, as are chew-cards containing peanut butter.<ref>{{Cite journal |last1=Jackson |first1=M. |last2=Hartley |first2=S. |last3=Linklater |first3=W. |date=2016 |title=Better food-based baits and lures for invasive rats ''Rattus'' spp. and the brushtail possum ''Trichosurus vulpecula'': a bioassay on wild, free-ranging animals |journal=Journal of Pest Science |volume=89 |issue=2 |pages=479–488 |bibcode=2016JPesS..89..479J |doi=10.1007/s10340-015-0693-8 |s2cid=13095387}}</ref> Poison control methods are effective in reducing rat populations to nonthreatening sizes, but rat populations often rebound to normal size within months. Besides their highly adaptive foraging behaviour and fast reproduction, the exact mechanisms for their rebound is unclear and are still being studied.<ref name="Innes">{{cite journal |author1=Innes, J. |author2=Warburton, B. |author3=Williams, D. |year=1995 |title=Large-scale Poisoning of Ship Rats (''Rattus rattus'') in Indigenous Forests of the North Island, New Zealand |url=http://www.nzes.org.nz/nzje/free_issues/NZJEcol19_1_5.pdf |journal=New Zealand Journal of Ecology |volume=19 |issue=1 |pages=5–17 |archive-url=https://web.archive.org/web/20110927230417/http://www.nzes.org.nz/nzje/free_issues/NZJEcol19_1_5.pdf |archive-date=27 September 2011 |access-date=22 April 2011}}</ref>

In 2010, the Sociedad Ornitológica Puertorriqueña (Puerto Rican Bird Society) and the Ponce Yacht and Fishing Club launched a campaign to eradicate the black rat from the Isla Ratones (Mice Island) and Isla Cardona (Cardona Island) islands off the municipality of Ponce, Puerto Rico.<ref>Wege, David (4 August 2010) [http://www.birdlife.org/community/2010/08/restauran-habitat-del-lagartijo-del-seco-anolis-cooki-en-la-isla-de-cardona-y-cayo-ratones/ Restauran hábitat del lagartijo del seco Anolis cooki en la Isla de Cardona y Cayo Ratones] {{Webarchive|url=https://web.archive.org/web/20110814173530/http://www.birdlife.org/community/2010/08/restauran-habitat-del-lagartijo-del-seco-anolis-cooki-en-la-isla-de-cardona-y-cayo-ratones/ |date=14 August 2011 }}. birdlife.org.</ref>

===Specific areas=== ====New Zealand==== The first species of rat introduced to New Zealand from Europe was ''Rattus norvegicus'', or the brown rat, as ''R. norvegicus'' was then the dominant rat in England. However, ''r. rattus'' became more common on ships in the mid-1800s, and black rats spread throughout the North Island from probably the early 1860s and the South Island from probably the late 1880s.<ref>{{cite journal |last1=Atkinson |first1=I.A.E. |year=1973 |title=Spread of the Ship Rat (''Rattus r. rattus'' L.) in New Zealand |journal=Journal of the Royal Society of New Zealand |volume=2 |issue=3 |pages=457–472 |bibcode=1973JRSNZ...3..457A |doi=10.1080/03036758.1973.10421869 |doi-access=free}}</ref> Brown rats were soon replaced as the dominant species by black rats, possibly due to their more optimal foraging habits.<ref>{{cite journal |last1=King |first1=Carolyn |last2=Miller |first2=Steven |date=2011 |title=Invasive European rats in Britain and New Zealand: Same species, different outcomes |url=https://www.researchgate.net/publication/230223984 |journal=Journal of Zoology |volume=285 |issue=3 |pages=172–179 |bibcode=2011JZoo..285..172K |doi=10.1111/j.1469-7998.2011.00827.x}}</ref> Due to their common behaviour of stealing eggs from bird nests, ship rats have caused a number of native bird species in New Zealand to become extinct, most recently the bush wren.<ref>{{cite web |last1=Brown |first1=Kerry |last2=Elliott |first2=Graeme |last3=Innes |first3=John |last4=Kemp |first4=Josh |title=Ship rat, stoat and possum control on mainland New Zealand: An overview of techniques, successes and challenges |url=https://www.doc.govt.nz/Documents/conservation/threats-and-impacts/animal-pests/ship-rat-stoat-possum-control.pdf}}</ref> Since the 1980s, many successful rat eradications have been performed across New Zealand's islands of ''R. rattus'', ''R. norvegicus'', and ''R. exulans'' (Polynesian rat), sometimes jointly, on islands such as Awaiti and Tawhitinui.<ref name="FortyYears">{{cite journal |last1=Towns |first1=David R. |last2=Broome |first2=Keith G. |date=2003 |title=From small Maria to massive Campbell: Forty years of rat eradications from New Zealand islands |url=https://www.tandfonline.com/doi/pdf/10.1080/03014223.2003.9518348 |journal=New Zealand Journal of Zoology |volume=30 |issue=4 |pages=377–398 |doi=10.1080/03014223.2003.9518348|url-access=subscription }}</ref> However, black rats continue to have a major presence on mainland New Zealand, and are at one of the highest risks for reinfestation out of all species of invasive rodents.{{r |FortyYears}}

=== Decline in population === Eradication projects have eliminated black rats from Lundy in the Bristol Channel (2006)<ref>{{Cite journal |last=Lock |first=J. |date=2006 |title=Eradication of brown rats ''Rattus norvegicus'' and black rats ''Rattus rattus'' to restore breeding seabird populations on Lundy Island, Devon, England |url=https://conservationevidencejournal.com/reference/pdf/2241 |volume=3 |journal=Conservation Evidence |pages=111–113}}</ref> and from the Shiant Islands in the Outer Hebrides (2016).<ref>{{Cite book |url=https://portals.iucn.org/library/node/48358 |title=Island invasives: scaling up to meet the challenge |date=2019 |publisher=IUCN |isbn=978-2-8317-1962-7 |editor-last1=Veitch |pages=138–146 |language=en |chapter=Scaling down (cliffs) to meet the challenge: the Shiants’ black rat eradication |doi=10.2305/iucn.ch.2019.ssc-op.62.en |hdl=1893/29131 |editor-last2=Clout |editor-first2=M.N. |editor-last3=Martin |editor-first3=A.R. |editor-last4=Russell |editor-first4=J.C. |editor-last5=West |editor-first5=C.J. |first=C.E. |last=Main |first2=E. |last2=Bell |first3=K. |last3=Floyd |first4=J. |last4=Tayton |first5=J. |last5=Ibbotson |first6=W. |last6=Whittington |first7=P.R. |last7=Taylor |first8=R. |last8=Reid |first9=K. |last9=Varnham |first10=T. |last10=Churchyard |first11=L. |last11=Bambini |first12=A. |last12=Douse |first13=T. |last13=Nicolson |first14=G. |last14=Campbell}}</ref> Populations probably survive on other islands (e.g. Inchcolm) and in localised areas of the British mainland.<ref>{{Cite news |work=The Scotsman |date=31 December 2018 |title=Revealed: Historic Scottish island home to black rats |url=https://www.scotsman.com/heritage-and-retro/heritage/revealed-historic-scottish-island-home-black-rats-2463871 |first=George |last=Mair}}</ref> Recent National Biodiversity Network data indicates very sparse populations around the U.K.,<ref>{{Cite web |title=''Rattus rattus'' (Linnaeus, 1758) |department=NBN Atlas |url=https://data.nbn.org.uk/Taxa/NHMSYS0000080213 |access-date=11 August 2016 |website=National Biodiversity Network}}</ref> and The Mammal Society has no records in the major port towns of Manchester, Liverpool or Glasgow for over 40 years,<ref>{{Cite web |title=Black rat |url=https://mammal.org.uk/british-mammals/black-rat |access-date=14 August 2025 |website=The Mammal Society}}</ref> areas which were historically population strongholds.

==See also== * Karni Mata Temple, Deshnoke, Rajasthan, India. * Urban plague

==References== {{Reflist}}

==Further reading== * List of books and articles about rats

==External links== {{Commons category|Rattus rattus}} *[https://web.archive.org/web/20080430202159/http://www.arkive.org/species/ARK/mammals/Rattus_rattus/ Photos and video] at ARKive

{{Murinae (Rattus)}}

{{Taxonbar|from=Q106133}} {{Authority control}}

Category:Rattus Category:Rodents of Asia Category:Rodents of Europe Category:Mammals of Azerbaijan Category:Mammals of Nepal Category:Stored-product pests Category:Mammals described in 1758 Category:Animal taxa named by Carl Linnaeus Category:Rodents of Borneo