{{Short description|Extinct species of rodent}} {{speciesbox | fossil_range = Late Pleistocene- Early Holocene | extinct = yes | genus = Peromyscus | species = nesodytes | authority = Wilson 1936 | synonyms = }}
The '''giant island deer mouse'''<ref name="Ainis">Ainis, Amira F. and Rene L. Vellanoweth (2012). [https://www.academia.edu/9829471/Expanding_the_Chronology_for_the_Extinct_Giant_Island_Deer_Mouse_Peromyscus_nesodytes_on_San_Miguel_Island_California_USA_PLEASE_SCROLL_DOWN_FOR_ARTICLE Expanding the Chronology for the Extinct Giant Island Deer Mouse (''Peromyscus nesodytes'') on San Miguel Island, California, USA.] ''Journal of Island & Coastal Archaeology'' 7:146–152.</ref> ('''''Peromyscus nesodytes''''') is believed to have become extinct approximately 8,000 years BP and lived during the late Pleistocene on California’s Channel Islands.<ref name="Guthrie, D.A. 1993, p. 405-416">Guthrie, D.A. (1993). New information on the prehistoric fauna of San Miguel Island: in F.G. Hochberg, ed., Third Channel Islands symposium, Santa Barbara, CA, Santa Barbara Museum of Natural History, p. 405-416.</ref> The giant island deer mice were about 35% larger than the current-day eastern deer mouse.<ref name="Ainis" />
==Overview== In 1934, Robert W. Wilson designated ''P. nesodytes'' as a new species after discovering a mouse bone (a right ramus of the mandible).<ref name="Wilson, R.W. 1936, p. 408-10">{{cite journal|last1= Wilson|first1=R. W.|title=A New Pleistocene Deer-Mouse from Santa Rosa Island, California|journal=Journal of Mammalogy|volume= 17|issue= 4|year= 1936|pages= 408–410|doi= 10.2307/1374408|jstor=1374408|s2cid=88366025 |url= https://authors.library.caltech.edu/99573/1/1374408.pdf}}</ref> He writes, “The outstanding character of ''P. nesodytes'' is its large size, which is greater than any living species of ''Peromyscus'' native to the United States.”<ref name="Wilson, R.W. 1936, p. 408-10"/> The only larger mice known are the extant mice of the genus ''Megadontomys'' found in Mexico and Central America.<ref name="Wilson, R.W. 1936, p. 408-10"/>
The mouse “generally considered ancestral to ''P. nesodytes''” is ''Peromyscus anyapahensis''.<ref>Guthrie, D.A. (1998). Fossil Vertebrates From Pleistocene Terrestrial Deposits on the Northern Channel Islands, Southern California: in Weigand, P.W., ed., Contributions to the geology of the Northern Channel Islands, Southern California: American Association of Petroleum Geologists, Pacific Section. MP 45.</ref>''P. anyapahensis'' is also extinct; it is smaller in body size than ''P. nesodytes''.<ref>White, J.A. (1966). [https://nhm.org/site/sites/default/files/pdf/contrib_science/CS96.pdf A new Peromyscus from the late Pleistocene of Anacapa Island, California, with notes on variation in ''Peromyscus Nesodytes'']: Los Angeles County Museum Contributions in Science no. 96, p. 1-8.</ref>
The extreme size of ''P. nesodytes'' follows Foster's rule of insular gigantism and dwarfism, in which some rodent species attain greater body size following their occupation of islands lacking a multitude of predators.<ref name="Wenner, A.M p 497-530">Wenner, A.M. and D.L. Johnson (1980). Land vertebrates on the California Channel Islands: Sweepstakes or Bridges? in D.M. Powers, ed. The California Islands, proceedings of a multi-disciplinary symposium, Santa Barbara, CA, Santa Barbara Museum of Natural History, p 497-530.</ref>
==Habitat== The habitat of ''P. nesodytes'' was confined to the northern Channel Islands. Remains of ''P. nesodytes'' have been found on San Miguel Island and Santa Rosa Island. The northern Channel Islands once comprised a “super-island” called Santa Rosae; increased sea levels have separated the islands for thousands of years.<ref name="Wenner, A.M p 497-530"/>
==Extinction== ''P. nesodytes'' probably became extinct following the possibly accidental introduction of a smaller mouse, ''Peromyscus maniculatus'', by the Chumash people, who originate from the Santa Barbara area.<ref name="Wenner, A.M p 497-530"/> The Chumash traded on the northern Channel Islands and could have been unknowing transporters of ''P. maniculatus'' to the islands. It has been noted that, on occasion, individuals of ''P. maniculatus'' could have secreted themselves in baskets of food and been unintentionally conveyed by boat to the islands for trading purposes.<ref>Walker, P. (1980). Archaeological evidence for the recent extinction of three terrestrial mammals on San Miguel Island: in D.M. Powers, ed. The California Islands, proceedings of a multi-disciplinary symposium, Santa Barbara, CA, Santa Barbara Museum of Natural History, p. 703-717.</ref>
''P. maniculatus'' probably fared better at avoiding the most frequent mouse predator on the islands, the barn owl, than did ''P. nesodytes''. A possible example of this appears in Daisy Cave, an archaeological site on San Miguel Island. Cave floor layers show fewer ''P. maniculatus'' remains in the older, deeper levels than in the newer, upper levels. Barn owls may have preferentially preyed on the larger species, ''P. nesodytes'', rather than on the smaller ''P. maniculatus''.<ref name="Guthrie, D.A. 1993, p. 405-416"/>
==References== {{Reflist}}
{{Taxonbar|from=Q7169429}}
Category:Pleistocene rodents Category:Peromyscus Category:Fauna of the Channel Islands of California Category:Pleistocene mammals of North America Category:Pleistocene species first appearances Category:Holocene species Category:Holocene extinctions Category:Endemic fauna of California Category:Pleistocene California Category:Fauna without expected TNC conservation status