{{Short description|Species of rodent}} {{About| the North American species|the South American genus also known as "Oldfield mice"|Thomasomys}} {{Speciesbox | status = LC | status_system = IUCN3.1 | status_ref = <ref name=iucn>{{cite iucn|last=Cassola|first=F.|year=2016|errata=2017|title=''Peromyscus polionotus''|doi=10.2305/IUCN.UK.2016-3.RLTS.T42654A22359556.en|article-number=e.T42654A115199876|access-date=24 April 2023}}</ref> | status2 = G5 | status2_system = TNC | status2_ref = <ref name=NS>{{cite NatureServe |id=2.106418 |title=''Peromyscus polionotus'' |access-date=15 May 2025}}</ref> | image = Peromyscus polionotus ammobates.jpg | image_caption = Oldfield mouse at the beach, Alabama | genus = Peromyscus | species = polionotus | authority = (Wagner, 1843) | synonyms = {{Collapsible list|bullets=yes|''Peromyscus polionotus'' subsp. ''polionotus'' <small>(Wagner, 1843)</small> |''Peromyscus polionotus'' subsp. ''ammobates'' <small>Bowen, 1968</small> |''Peromyscus polionotus'' subsp. ''phasma'' <small>Bangs, 1898</small> |''Peromyscus polionotus'' subsp. ''allophrys'' <small>Bowen, 1968</small> |''Peromyscus polionotus'' subsp. ''trissyllepsis'' <small>Bowen, 1968</small> |''Peromyscus polionotus'' subsp. ''niveiventris'' <small>(Chapman, 1889)</small> |''Mus polionotus'' <small>Wagner, 1843</small> |''Peromyscus subgriseus'' subsp. ''baliolus'' <small>Bangs, 1898</small> |''Peromyscus phasma'' <small>Bangs, 1898</small> |''Hesperomys niveiventris'' <small>Chapman, 1889</small> |''Peromyscus polionotus'' subsp. ''albifrons'' <small>Osgood, 1909</small> |''Peromyscus polionotus'' subsp. ''colemani'' <small>Schwartz, 1954</small> |''Peromyscus polionotus'' subsp. ''decoloratus'' <small>A.H. Howell, 1939</small> |''Peromyscus polionotus'' subsp. ''leucocephalus'' <small>A.H. Howell, 1920</small> |''Peromyscus leucocephalus'' <small>A.H. Howell, 1920</small> |''Peromyscus polionotus'' subsp. ''lucubrans'' <small>Schwartz, 1954</small> |''Peromyscus polionotus'' subsp. ''peninsularis'' <small>A.H. Howell, 1939</small> |''Peromyscus polionotus'' subsp. ''rhoadsi'' <small>Bangs, 1898</small> |''Peromyscus subgriseus'' subsp. ''rhoadsi'' <small>Bangs, 1898</small> |''Peromyscus polionotus'' subsp. ''subgriseus'' <small>(Chapman, 1893)</small> |''Sitomys viveiventris'' subsp. ''subgriseus'' <small>Chapman, 1893</small> |''Peromyscus polionotus'' subsp. ''griseobracatus'' <small>Bowen, 1968</small> |''Sitomys niveiventris'' subsp. ''subgriseus'' <small>Chapman, 1893</small> |''Peromyscus polionotus'' subsp. ''sumneri'' <small>Bowen, 1968</small> }} |synonyms_ref=<ref name=itis>{{ITIS|taxon=''Peromyscus polionotus'' (Wagner, 1843)|id=180290|access-date=24 April 2023}}</ref> | range_map = Elife06813f002.jpg | range_map_caption = {{legend0|#004c1f|&nbsp;native range}} }}

The '''oldfield mouse''', '''oldfield deermouse'''<ref name=itis/> or '''beach mouse''' ('''''Peromyscus polionotus''''') is a nocturnal species of rodent in the family Cricetidae. It is a species of the genus ''Peromyscus'', a closely related group of New World mice often called "deermice", that primarily eats seeds. It lives in holes throughout the Southeastern United States in beaches and sandy fields. Predators to these mice include birds and mammals. In 2016, these mice were in the least concern category on the IUCN Red List with certain subspecies classified as extinct, critically endangered, endangered or near threatened.

==Distribution and habitat== The oldfield mouse occurs only in the southeastern United States, ranging from Florida to Tennessee.<ref name=iucn/> They primarily live in beaches and sandy fields.<ref name="Wtr308">Whitaker 1998, p. 308</ref>

==Description== The mouse has fawn-colored upperparts and grey to white underparts through most of its range, but on white sandy beaches, the mouse is light or even white. Inland populations are darker and smaller with shorter tails that are dusky above and white below. General body and tail color may vary slightly depending upon geographical location.<ref name="Wtr308"/> {| class="wikitable" style="margin:1em auto;" ! colspan="3" |Measurements (20 adults from Alabama, Florida, and Georgia)<ref name="Wtr308"/> |- !Statistic !Average !Range |- |Length |{{convert|127|mm|abbr=on}} |{{convert|122|-|138|mm|abbr=on}} |- |Tail |{{convert|47|mm|abbr=on}} |{{convert|40|-|51|mm|abbr=on}} |- |Hind foot |{{convert|16.5|mm|abbr=on}} |{{convert|15|-|18|mm|abbr=on}} |- |Weight | colspan="2" |{{convert|8|-|19|g|abbr=on}} |- |Diploid number | colspan="2" |48 |- |Tooth formula | colspan="2" |{{DentalFormula|upper=1.0.0.3|lower=1.0.0.3}} = 16 |- |}

==Behavior== The mouse is primarily nocturnal.<ref name=iucn/> Oldfield mice construct elaborate burrow systems with entrance tunnels, nest chambers, and escape routes.<ref>{{cite journal |last=Weber |first=J. N. |author2=Peterson, B. K. |author3=Hoekstra, H. E. |title=Discrete genetic modules are responsible for complex burrow evolution in Peromyscus mice |journal=Nature |year=2013 |volume=493 |issue=7432 |pages=402–405 |doi=10.1038/nature11816}}</ref>

===Diet=== ''P. polionotus'' is omnivorous and the principal diet is seasonal seeds of wild grasses and forbs, but blackberries, acorns, and wild peas may be consumed.<ref name=iucn/><ref>Whitaker 1998, p. 309</ref><ref name="Wooten">Wooten</ref>

===Shelter=== These mice dig holes in earth to create homes. Spiders, snakes, and other animals may move into a burrow.<ref name="Wtr308-9">Whitaker 1998, p. 308&ndash;9</ref>

===Reproduction=== {| class="wikitable" style="margin:1em auto;" !colspan="2"|Reproduction<ref>Whitaker 1998, p. 309–10</ref> |- |Sexual maturity (female) |30 days |- |Gestation |23–24 days |- |Litter size |3–4 (viviparous) |- |Weight at birth |{{convert|1.1|-|2.2|g|abbr=on}} |- |Weaning |20–25 days |- |Adult weight |{{convert|8|-|10|g|abbr=on}} |- |}

===Survival=== Birds and mammals prey upon the oldfield mouse. Various types of parasites can effect oldfield mice, with nematodes being the main ones.<ref>Whitaker 1998, p. 310</ref> One mouse survived in captivity for 5.5 years.<ref name="Peromyscus polionotus">''Peromyscus polionotus''</ref>

==Conservation== In 2010, the beach mouse was in the least concern category on the IUCN Red List. For the beach mouse's subspecies, out of sixteen known, one is extinct, one was listed critically endangered, four endangered and two near threatened.<ref name=iucn/>

Under the Endangered Species Act of 1973, the following beach mice are protected as endangered or threatened subspecies: *Southeastern beach mouse (''P. p. niveiventris'') – Threatened<ref>{{cite web|url=https://ecos.fws.gov/ecp/species/3951|title=Southeastern beach mouse (''Peromyscus polionotus niveiventris'')|access-date=24 April 2023|website=Environmental Conservation Online System|publisher=U.S. Fish & Wildlife Service}}</ref><ref name=FR54>{{Federal Register|54|20598}}</ref> *Anastasia Island beach mouse (''P. p. phasma'') – Endangered<ref name=FR54/><ref>{{cite web|url=https://ecos.fws.gov/ecp/species/5522|title=Anastasia Island beach mouse (''Peromyscus polionotus phasma'')|website=Environmental Conservation Online System|publisher=U.S. Fish & Wildlife Service|access-date=24 April 2023}}</ref> *Alabama beach mouse (''P. p. ammobates'') – Endangered<ref>{{cite web|url=https://ecos.fws.gov/ecp/species/6956|title=Alabama beach mouse (''Peromyscus polionotus ammobates'')|website=Environmental Conservation Online System|publisher=U.S. Fish & Wildlife Service|access-date=24 April 2023}}</ref><ref name=FR50>{{Federal Register|50|23872}}</ref> *Perdido Key beach mouse (''P. p. trissyllepsis'') – Endangered<ref name=FR50/><ref>{{cite web|url=https://ecos.fws.gov/ecp/species/7394|title=Perdido Key beach mouse (''Peromyscus polionotus trissyllepsis'')|website=Environmental Conservation Online System|publisher=U.S. Fish & Wildlife Service|access-date=24 April 2023}}</ref> *Choctawhatchee beach mouse (''P. p. allophrys'') – Endangered<ref name=FR50/><ref>{{cite web|url=https://ecos.fws.gov/ecp/species/3520|title=Choctawhatchee beach mouse (''Peromyscus polionotus allophrys'')|website=Environmental Conservation Online System|publisher=U.S. Fish & Wildlife Service|access-date=24 April 2023}}</ref> *St. Andrew beach mouse (''P. p. peninsularis'') – Endangered<ref>{{cite web|url=https://ecos.fws.gov/ecp/species/4111|title=St. Andrew beach mouse (''Peromyscus polionotus peninsularis'')|website=Environmental Conservation Online System|publisher=U.S. Fish & Wildlife Service|access-date=24 April 2023}}</ref><ref>{{Federal Register|63|70053}}</ref>

The pallid beach mouse (''P. p. decoloratus'') is presumed extinct.<ref>{{cite web|url=https://animaldiversity.org/accounts/Peromyscus_polionotus/|title=''Peromyscus polionotus''|last=Foust|first=Desirae|editor-last=Demastes|editor-first=Jim|year=2002|website=Animal Diversity Web|access-date=24 April 2023}}</ref><ref>{{cite web|url=https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.100123/Peromyscus_polionotus_decoloratus|title=''Peromyscus polionotus decoloratus''|website=NatureServe Network Biodiversity Location Data accessed through NatureServe Explorer|author=NatureServe|publisher=NatureServe|location=Arlington, Virginia|date=7 April 2023|access-date=24 April 2023}}</ref> The Santa Rosa beach mouse (''P. p. leucocephalus'')<ref>{{cite web|url=https://ecos.fws.gov/ecp/species/2419|title=Santa Rosa beach mouse (''Peromyscus polionotus leucocephalus'')|website=Environmental Conservation Online System|publisher=U.S. Fish & Wildlife Service|access-date=24 April 2023}}</ref> is listed as critically imperiled by NatureServe.<ref>{{cite web|url=https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.101599/Peromyscus_polionotus_leucocephalus|title=''Peromyscus polionotus leucocephalus''|website=NatureServe Network Biodiversity Location Data accessed through NatureServe Explorer|author=NatureServe|publisher=NatureServe|location=Arlington, Virginia|date=7 April 2023|access-date=24 April 2023}}</ref>

==Predation== In Florida, beach mice may be eaten by some growth stage of invasive snakes such as Burmese pythons, reticulated pythons, Southern African rock pythons, Central African rock pythons, boa constrictors, yellow anacondas, Bolivian anacondas, dark-spotted anacondas, and green anacondas.<ref>{{Cite book|title=Final Environmental Assessment For The Large Constrictor Snakes Listed As Injurious Wildlife Lisyed As Injurious Wildlife under the Lacey Act|date=January 2012|publisher=U.S. Fish and Wildlife Service}}</ref>

==References== {{Commons category|Peromyscus polionotus}} ;Footnotes {{Reflist}} ;Works cited {{Refbegin}} *{{citation |title=''Peromyscus polionotus'' |publisher=Human Ageing Genomic Resources |url=http://genomics.senescence.info/species/entry.php?species=Peromyscus_polionotus |access-date=February 10, 2010}} *{{citation |author=Whitaker, John O. Jr. |author2=Hamilton, William J. Jr. |year=1998 |title=Mammals of the Eastern United States |edition=3 |location=Ithaca, NY |publisher=Cornell University Press |isbn=0-8014-3475-0|url=https://books.google.com/books?id=5fVymWAez-YC}} *{{citation |author=Wooten, Michael C. |title=Peromyscus polionotus: Oldfield mouse |publisher=Auburn University, SC |url=http://wotan.cse.sc.edu/perobase/systematics/p_polion.htm |access-date=February 11, 2010 |archive-url=https://web.archive.org/web/20100613060003/http://wotan.cse.sc.edu/perobase/systematics/p_polion.htm |archive-date=June 13, 2010 }} {{Refend}}

{{Neotominae}} {{Taxonbar|from=Q575053}} {{Authority control}}

Category:Peromyscus Category:Mammals described in 1843 Category:Endemic rodents of the United States Category:Taxonomy articles created by Polbot