Editing Virginia opossum (section)

== Behavior ==
=== "Playing possum" ===
[[File:PlayingPossum.jpg|thumb|When injured or threatened (e.g., by a dog), the Virginia opossum is known to [[feign death]] or "play possum".|alt=]]If threatened, an opossum will either flee or take a stand. To appear threatening, an opossum will first bare its 50 teeth, snap its jaw, hiss, drool, and stand its fur on end to look bigger.<ref name=":72">{{Cite web|title=Virginia Opossum|url=https://www.psu.edu/dept/nkbiology/naturetrailOLD/speciespages/opossum.htm|access-date=2020-09-28|website=www.psu.edu |archive-url=https://web.archive.org/web/20100601193804/https://www.psu.edu/dept/nkbiology/naturetrailOLD/speciespages/opossum.htm |archive-date=2010-06-01 |url-status=dead}}</ref> If this does not work, the Virginia opossum is noted for [[Apparent death|feigning death]] in response to extreme fear.<ref name=":82">{{Cite web|title=Opossum Defense Mechanisms {{!}} Opossum Society of the United States|url=https://opossumsocietyus.org/general-opossum-information/opossum-defense-mechanisms/|access-date=2020-09-28|language=en-US}}</ref> This is the genesis of the term "playing possum", which means pretending to be dead or injured with intent to deceive.<ref>{{Cite web|title=PLAY POSSUM {{!}} definition in the Cambridge English Dictionary|url=https://dictionary.cambridge.org/us/dictionary/english/play-possum|access-date=2020-09-28|website=dictionary.cambridge.org|language=en-US}}</ref>

In this inactive state it lies limp and motionless on its side, mouth and eyes open, tongue hanging out, and feet clenched.<ref name=":72" /> Fear can also cause the opossum to release a green fluid from its anus with a putrid odor that repels predators.<ref name=":82" /><ref name=":142">{{Cite web|title=Give opossums a break|url=https://www.caryinstitute.org/news-insights/media-coverage/give-opossums-break|access-date=2020-09-30|website=Cary Institute of Ecosystem Studies|date=30 March 2015 |language=en}}</ref> Heart rate drops by half, and breathing rate is so slow and shallow it is hardly detectable.<ref name=":72" /> Death feigning normally stops when the threat withdraws, and it can last for several hours.<ref name=":72" /><ref name=":142" /> Besides discouraging animals that eat live prey, playing possum also convinces some large animals that the opossum is no threat to their young.<ref name=":82" /> "Playing possum" in response to threats from oncoming traffic often results in death.<ref name=":92">{{Cite web|title=Why you should brake for opossums|url=https://www.caryinstitute.org/news-insights/podcast/why-you-should-brake-opossums|access-date=2020-09-28|website=Cary Institute of Ecosystem Studies|date=23 July 2012 |language=en}}</ref>

=== Diet ===
[[File:Possum rejects bagel.webm|thumb|Night camera shows video of an opossum considering a bagel before walking away]]
Opossums are [[Omnivore|omnivorous]] (sometimes said to be [[insectivorous]]) and eat a wide range of plant-based food, as well as animal-based food like small invertebrates, [[carrion]], eggs, fish, amphibians, reptiles, birds, small mammals, and other small animals.<ref name=":102">{{Cite web|date=2018-01-05|title=Virginia opossum|url=https://nationalzoo.si.edu/animals/virginia-opossum|access-date=2020-09-28|website=Smithsonian's National Zoo|language=en}}</ref>

[[Insects]] such as grasshoppers, crickets, and beetles make up the bulk of the animal foods eaten by opossums.<ref name=":112">{{Cite web|title=Opossum {{!}} Adirondack Ecological Center {{!}} SUNY ESF {{!}} College of Environmental Science and Forestry|url=https://www.esf.edu/aec/adks/mammals/opossum.htm#:~:text=Social%20system%20-%20Opossums%20are%20solitary,may%20share%20a%20winter%20den.|access-date=2020-09-28|website=www.esf.edu}}</ref> It has been stated that opossums eat up to 95% of the [[tick]]s they encounter<ref name=":92"/><ref name=":13">{{Cite web|last=Maurer|first=Steph|title=The Helpful Opossum {{!}} Wildlife Medical Clinic at Illinois|url=https://vetmed.illinois.edu/wildlife/2019/06/05/the-helpful-opossum-2/|access-date=2022-04-24|language=en-US |archive-url=https://web.archive.org/web/20210716193836/https://vetmed.illinois.edu/wildlife/2019/06/05/the-helpful-opossum-2/ |archive-date=2021-07-16 |url-status=dead}}</ref> and may eat up to 5,000 ticks per season, helping to prevent the spread of tick-born illnesses, including [[Lyme disease]] and [[Rocky Mountain spotted fever]].<ref name=":13" /> This interpretation has been challenged.<ref name="Hennessy2021">{{cite journal |last1=Hennessy |first1=C. |last2=Hild |first2=K. |date=September 2021 |title=Are Virginia opossums really ecological traps for ticks? Groundtruthing laboratory observations |url=https://www.sciencedirect.com/science/article/abs/pii/S1877959X21001333 |journal=Ticks and Tick-Borne Diseases |volume=12 |issue=5 |page=101780 |doi=10.1016/j.ttbdis.2021.101780 |pmid=34298355 |access-date=2022-04-20}}</ref>  A widely publicized 2009 study by the [[Cary Institute of Ecosystem Studies|Cary Institute]] indicated that Virginia opossums in a laboratory setting could eat thousands of ticks per week [[Personal grooming#In animals|grooming]].<ref>{{cite web |last1=Kirchner |first1=Jane |title=Opossums: Unsung Heroes in the Fight Against Ticks and Lyme Disease |url=https://blog.nwf.org/2017/06/opossums-unsung-heroes-in-the-fight-against-ticks-and-lyme-disease/ |website=National Wildlife Federation |date=13 June 2017 |access-date=26 August 2019}}</ref><ref>{{cite news |last1=Bayly |first1=Julia |title=Turns out, opossums may not actually like eating ticks |url=https://www.bangordailynews.com/2022/03/24/homestead/turns-out-opossums-dont-really-like-eating-ticks-xoasq1i29i/ |access-date=27 October 2022 |work=Bangor Daily News |date=24 March 2022}}</ref> However, subsequent studies of the stomach contents of wild Virginia opossums have not found any ticks in their diet.<ref>{{cite journal |last1=Hennessy |first1=Cecilia |last2=Hild | first2=Kaitlyn |title=Are Virginia opossums really ecological traps for ticks? Groundtruthing laboratory observations |url=https://pubmed.ncbi.nlm.nih.gov/34298355/ |journal=Ticks and Tick-Borne Diseases |date=15 July 2021 |volume=12 |issue=5 |page=101780 |doi=10.1016/j.ttbdis.2021.101780 |pmid=34298355 |access-date=18 January 2021}}</ref>

Small animals include young rabbits, meadow voles, mice, rats, birds, snakes, lizards, frogs, fish, crayfish, gastropods, and earthworms.<ref name=":12">{{Cite web|title=Opossum Management Guidelines--UC IPM|url=http://ipm.ucanr.edu/PMG/PESTNOTES/pn74123.html#:~:text=Opossums%20carry%20diseases%20such%20as,fleas,%20especially%20in%20urban%20environments.|access-date=2020-09-28|website=ipm.ucanr.edu}}</ref><ref>{{Cite web|url=https://www.chesapeakebay.net/S=0/fieldguide/critter/virginia_opossum|title=Virginia Opossum &#124; Chesapeake Bay Program|website=www.chesapeakebay.net}}</ref><ref>{{Cite web|url=https://lafeber.com/vet/basic-information-sheet-virginia-opossum/|title=Basic Information Sheet: Virginia Opossum|date=June 11, 2018}}</ref><ref>{{Cite web|url=https://aaric.org/2020/09/11/virginia-opossum/|title=Virginia opossum|date=September 11, 2020}}</ref><ref name="Martina">{{Cite web|url=https://animaldiversity.org/accounts/Didelphis_virginiana/|title=Didelphis virginiana (Virginia opossum)|first=Leila Siciliano|last=Martina|website=Animal Diversity Web}}</ref> The Virginia opossum has been found to be very resistant to snake venom.<ref>{{cite journal|author=Sharon A. Jansa|author2=Robert S. Voss|year=2011|title=Adaptive evolution of the venom-targeted vWF protein in opossums that eat pitvipers|journal=PLOS ONE|volume=6|issue=6|pages=e20997|doi=10.1371/journal.pone.0020997|pmc=3120824|pmid=21731638|bibcode=2011PLoSO...620997J|doi-access=free}}</ref><ref name=":13" /> Attracted to carrion on the side of the highway, opossums are at an increased risk of being hit by motor vehicles.<ref name=":142"/>

Plant foods are mainly eaten in late summer, autumn, and early winter.<ref name=":112"/> These include raspberries, blackberries, apples, acorns, beechnuts, seeds, grains, bulbs, and vegetables.<ref name=":112"/><ref name="Martina"/> [[Diospyros virginiana|Persimmons]] are one of the opossum's favorite foods during the autumn.<ref>Sparano, Vin T. 2000. The Complete outdoors encyclopedia. St. Martin's Press. {{ISBN|0-312-26722-3}}</ref> Opossums in urban areas scavenge from bird feeders, vegetable gardens, compost piles, garbage cans, and food dishes intended for dogs and cats.<ref name=":112"/><ref name=":12" />[[File:Possum122708.JPG|thumb|Virginia opossum in northeastern Ohio]]

Opossums in captivity are known to engage in [[cannibalism]], though this is probably uncommon in the wild.<ref>[http://www.opossumsocietyus.org/cannibalism_in_the_opossum.htm Cannibalism in the Opossum]. Opossum Society. Accessed May 7, 2007.</ref> Because of this, placing an injured opossum in a confined space with its healthy counterparts is inadvisable.

=== Seasonality ===
The Virginia opossum is most active during the spring and summer.<ref name=":112" /> It does not hibernate but reduces its activity during the winter.<ref name=":102" /><ref>{{cite web|title=Virginia Opossum Didelphis virginiana|url=http://enature.com/fieldguides/detail.asp?allSpecies=y&searchText=opossum&curGroupID=5&lgfromWhere=&curPageNum=1|url-status=dead|archive-url=https://web.archive.org/web/20110517185002/http://enature.com/fieldguides/detail.asp?allSpecies=y&searchText=opossum&curGroupID=5&lgfromWhere=&curPageNum=1|archive-date=2011-05-17|access-date=2009-03-24|work=eNature.com|publisher=Shearwater Marketing Group}}</ref> It may not leave its den for several days if the temperature drops below {{convert|-7|to|-4|C|F}}.<ref name=":112" /> Both males and females are at greater risk of injury during breeding season.<ref name=":15">{{Cite web|title=Reproduction – Life Cycle {{!}} Opossum Society of the United States|url=https://opossumsocietyus.org/general-opossum-information/opossum-reproduction-lifecycle/|access-date=2020-09-30|language=en-US}}</ref> Males extend their range in search of mates which puts them at greater risk of injury from motor vehicles and predators as they venture into unfamiliar territory.<ref name=":15" /> Females carrying young are slower moving and have to forage earlier in the evening and later into the night, also increasing their risk of injury from motor vehicles and predation.<ref name=":15" />

===Reproduction===
[[File:Didelphis virginiana with young.JPG|thumb|Carrying her young]]The breeding season for the Virginia opossum can begin as early as December and continue through October with most young born between February and June.<ref name=":15" /> A female opossum may have one to three litters per year.<ref name=":15" /> During the mating season, the male attracts the female by making clicking sounds with his mouth.<ref name=":15" /> The female's [[Estrous cycle|estrus cycle]] is 28 days and lasts 36 hours.<ref name=":15" /> Gestation lasts 11–13 days and the average litter size is 8–9 infants, although over 20 infants may be born.<ref name=":15" />  Opossums have a very high [[mortality rate]] of their young; only one in ten offspring survive to reproductive adulthood.<ref>{{cite book|last1=Tyndale-Biscoe|first1=Hugh|title=Life of marsupials|date=2008|publisher=CSIRO|isbn=9780643092204|edition=[New.]|location=Collingwood|pages=105–138}}</ref>

Newborns are the size of a [[Honey bee|honeybee]].<ref name=":112" /> Once delivered through the median vagina or central birth canal, newborn opossums climb up into the female opossum's pouch and latch onto one of her 13 teats.<ref name=":15" /> The young remain latched for two months and in the pouch for {{frac|2|1|2}} months.<ref name=":15" /> The young then climb onto the mother's back, where she carries them for the remainder of their time together.<ref name=":15" /> It is during this time that the young learn survival skills.<ref name=":15" /> They leave their mother after about four or five months.<ref>{{cite web|title=Reproduction – Life Cycle - Opossum Society of the United States|url=http://opossumsocietyus.org/general-opossum-information/opossum-reproduction-lifecycle/|website=opossumsocietyus.org}}</ref>

Like all female [[marsupial]]s, the female's reproductive system is bifid, with two lateral vaginae, uteri, and ovaries.<ref name=":16">{{Cite book|last=Krause|first=William J.|title=The Opossum: Its Amazing Story|publisher=Department of Pathology and Anatomical Sciences, School of Medicine, University of Missouri, Columbia, Missouri|year=2005|isbn=0-9785999-0-X}}</ref> The male's penis is also bifid, with two heads, and as is common in New World marsupials, the sperm pair up in the testes and only separate as they come close to the egg.<ref name=":16" />  Males have three pairs of [[Cowper's gland]]s.<ref>Martan, Jan. [https://ilacadofsci.com/wp-content/uploads/2013/09/076-01-print.pdf "The genital tract of the male opossum Didelphis marsupialis virginiana and other marsupials."] Trans. I 11 (1983): 3-28.</ref>