Editing Brown rat (section)

=== Communication ===
Brown rats are capable of producing ultrasonic vocalizations. As pups, young rats use different types of ultrasonic cries to elicit and direct maternal search behavior,<ref>{{cite journal |doi=10.1037/0735-7036.108.3.298 | pmid = 7924260 | last1 = Brunelli | first1 = S.A.| last2 = Shair | first2 = H.N.| year = 1994 | last3 = Hofer | first3 = M.A. | title = Hypothermic vocalizations of rat pups (Rattus norvegicus) elicit and direct maternal search behavior |journal = [[Journal of Comparative Psychology]] | volume = 108 | issue = 3| pages = 298–303}}</ref> as well as to regulate their mother's movements in the nest.<ref>{{cite journal | doi = 10.1016/0163-1047(92)90363-9 | pmid = 1456932 |last1=White, N. | last2 = Adox, R. |name-list-style=amp |year=1992 |last3=Reddy, A. |last4 = Barfield, R. | title = Regulation of rat maternal behavior by broadband pup vocalizations |journal = [[Behavioral and Neural Biology]] | volume = 58 |issue = 2| pages = 131–137}}</ref> Although pups produce ultrasounds around any other rats at the age of 7 days, by 14 days old they significantly reduce ultrasound production around male rats as a defensive response.<ref>{{cite journal |doi=10.1037/0735-7036.106.1.69 | last1 = Takahashi | first1 = L.K. |year = 1992 | title = Developmental expression of defensive responses during exposure to conspecific adults in preweanling rats (''Rattus norvegicus'') |url=https://zenodo.org/record/1231486| journal = Journal of Comparative Psychology | volume = 106 | issue = 1| pages = 69–77 | pmid = 1313347}}</ref> Adult rats will emit ultrasonic vocalizations in response to predators or perceived danger;<ref>{{cite journal | doi = 10.1007/s10519-004-0858-3 | pmid = 15674535 | last1 = Brudzynski, S.M. | year = 2005 |title=Principles of Rat Communication: Quantitative Parameters of Ultrasonic Calls in Rats |url=http://www.cursoecologia.ufba.br/Arquivos/Comunicacao_Animal/rat_communication.pdf | journal = [[Behavior Genetics (journal)|Behavior Genetics]] | volume = 35 | issue = 1 | pages = 85–92 | citeseerx = 10.1.1.472.2300 | s2cid = 15888375 | access-date = 1 November 2017 | archive-url = https://web.archive.org/web/20170922005839/http://www.cursoecologia.ufba.br/Arquivos/Comunicacao_Animal/rat_communication.pdf | archive-date = 22 September 2017 }}</ref> the frequency and duration of such cries depends on the sex and reproductive status of the rat.<ref>{{cite journal | doi = 10.1037/0735-7036.106.3.270 | last1 = Blanchard | first1 = R.J. | last2 = Agullana | first2 = R. |name-list-style=amp | year = 1992 | last3=McGee |first3=L. |last4=Weiss | first4 = S. | last5 = Blanchard | first5 = D.C. | title = Sex differences in the incidence and sonographic characteristics of antipredator ultrasonic cries in the laboratory rat (''Rattus norvegicus'') |journal=Journal of Comparative Psychology | volume = 106 | issue = 3| pages = 270–277 | pmid = 1395496}}</ref><ref>{{cite journal | doi = 10.1037/0735-7036.107.4.373 | last1 = Haney | first1 = M. | last2 = Miczek |first2=K.A. | year = 1993 | title = Ultrasounds during agonistic interactions between female rats (''Rattus norvegicus'') | journal=Journal of Comparative Psychology |volume=107 |issue=4| pages=373–379 |pmid = 8112049}}</ref> The female rat also emit ultrasonic vocalizations during mating.<ref>{{cite journal | doi = 10.1016/S0003-3472(85)80002-6 | last1=Thomas |first1=D.A. | last2=Barfield | first2 = R.J. |name-list-style=amp |year=1985 |title=Ultrasonic vocalization of the female rat (''Rattus norvegicus'') during mating |journal=[[Animal Behaviour (journal)|Animal Behaviour]] |volume=33 | issue=3| pages=720–725 |s2cid=53193219}}</ref>

Rats may also emit short, high frequency, ultrasonic, socially induced vocalization during rough and tumble play, before receiving [[morphine]], or mating, and when tickled. The vocalization, described as a distinct "chirping", has been likened to [[laughter]], and is interpreted as an expectation of something rewarding.<ref>{{cite web|url=http://www.sciencenews.org/articles/20010728/fob9.asp|archive-url=https://web.archive.org/web/20040505115335/http://sciencenews.org/articles/20010728/fob9.asp|archive-date=2004-05-05|title=Search Content|work=Science News}}</ref> Like most rat vocalizations, the chirping is too high in pitch for humans to hear without special equipment. [[Bat detector]]s are often used by pet owners for this purpose.

In research studies, the chirping is associated with positive emotional feelings, and social bonding occurs with the tickler, resulting in the rats becoming conditioned to seek the tickling. However, as the rats age, the tendency to chirp appears to decline.<ref>{{cite journal |doi=10.1016/S0031-9384(03)00159-8 |last1=Panksepp |pmid= 12954448 |first1=J. |last2=Burgdorf |first2 = J. |name-list-style=amp |title="Laughing" rats and the evolutionary antecedents of human joy? |year=2003 |pages=533–47 |issue= 3 |volume=79 |journal=Physiology & Behavior |s2cid =14063615 |url=http://www.psych.umn.edu/courses/fall06/macdonalda/psy4960/Readings/PankseppRatLaugh_P&B03.pdf}}</ref>

Brown rats also produce communicative noises capable of being heard by humans. The most commonly heard in domestic rats is bruxing, or teeth-grinding, which is most usually triggered by happiness, but can also be 'self-comforting' in stressful situations, such as a visit to the vet. The noise is best described as either a quick clicking or 'burring' sound, varying from animal to animal. Vigorous bruxing can be accompanied by boggling, where the eyes of the rat rapidly bulge and retract due to movement of the lower jaw muscles behind the eye socket.<ref>{{cite web|url=https://petpartners.org/wp-content/uploads/2015/07/Rat-Behavior-Packet.pdf | title = Rat Behaviour Packet }}</ref>

In addition, they commonly squeak along a range of tones from high, abrupt pain squeaks to soft, persistent 'singing' sounds during confrontations.