This is a list of the mammal species recorded on Christmas Island. The island had five native and endemic land mammal species, of which three are now presumed to be extinct.^[1] In addition, five wild mammals have been introduced to Christmas Island since settlement.

Introduced cats and dogs are a threat to native wildlife on Christmas Island and can carry potentially dangerous pathogens, such as Leptospira.^[2] In 2014, the Australian Government announced a $500,000 investment to help eradicate stray and feral cats on the island, with the aim of complete eradication by 2020.^[3] As of 2016, all pet cats on Christmas Island have been registered and de-sexed and no further cats will be permitted onto the island.^[4]

Name	Species authority	Order	Family	Notes
Feral cat[5]	Felis catus Linnaeus, 1758	Carnivora	Felidae	introduced
Feral dog[5]	Canis lupus familiaris Linnaeus, 1758	Carnivora	Canidae	introduced

Christmas Island was once home to two native bat species, of which only one is extant. The Christmas Island pipistrelle was endemic to the island until 2009, when the last individual was recorded. In 2016, the species was assessed as extinct by the International Union for Conservation of Nature.^[6] The remaining native bat species Pteropus natalis (Christmas Island flying fox) is classified as critically endangered.^[7]

Name	Species authority	Order	Family	Notes	Red List
Christmas Island pipistrelle	Pipistrellus murrayi Andrews, 1900	Chiroptera	Vespertilionidae	endemic, extinct – last reported in 2009[8]	7 [6]
Christmas Island flying fox	Pteropus natalis Thomas, 1887	Chiroptera	Pteropodidae	endemic[9]	7 [7][9]

The Christmas Island shrew, once abundant on the island, has been very rare since the early twentieth century.^[10] Since 1909, only four confirmed individuals have been recorded: two in 1958, and two in 1985.^[10]

Name	Species authority	Order	Family	Notes	Red List
Christmas Island shrew	Crocidura trichura Dobson, 1889	Eulipotyphla	Soricidae	endemic – possibly extinct – last observed in 1985[1]	7 [10]

At the time of human settlement, Christmas Island hosted two endemic rodents, the bulldog rat and Maclear's rat. However, both species were extinct by 1908.^[11][12] There is evidence that black rats, introduced to the island in 1899, carried the infectious parasite Trypanosoma lewisi, which was fatal to the native rodents.^[13]

Name	Species authority	Order	Family	Notes	Red List
House mouse[5]	Mus musculus Linnaeus, 1758	Rodentia	Muridae	introduced	7 [14]
Polynesian rat[15]	Rattus exulans Peale, 1848	Rodentia	Muridae	introduced	7 [15]
Maclear's rat	Rattus macleari Thomas, 1888	Rodentia	Muridae	endemic – extinct	7 [11]
Bulldog rat	Rattus nativitatis Thomas, 1888	Rodentia	Muridae	endemic – extinct	7 [12]
Black rat[5]	Rattus rattus Linnaeus, 1758	Rodentia	Muridae	introduced in 1899[13]	7 [16]

Name	Species authority	Order	Family	Notes	Red List
Humpback whale	Megaptera novaeangliae Gray, 1846	Cetacea	Balaenopteridae	native migrant[17]	7 [18]
Blue whale	Balaenoptera musculus Linnaeus, 1758	Cetacea	Balaenoptiidae	migrant[17]	7 [19]
Southern fin whale	Balaenoptera physalus quoyi Linnaeus, 1758	Cetacea	Balaenoptiidae	native migrant or resident	7
Sei whale	Balaenoptera borealis schlegelii Linnaeus, 1758	Cetacea	Balaenoptiidae	native migrant[17]	7 [20]
Bryde's whale	Balaenoptera brydei Olsen, 1913[21]	Cetacea	Balaenoptiidae	native migrant or resident	7
Antarctic minke whale	Balaenoptera bonaerensis Linnaeus, 1758	Cetacea	Physeteridae	native migrant	7
Sperm whale	Physeter macrocephalus Linnaeus, 1758	Cetacea	Physeteridae	native migrant or resident	7 [22]
Short-finned pilot whale	Globicephala macrorhynchus Gray, 1846	Cetacea	Globicephala	native migrant or resident	7 [23]
Killer whale	Orcinus orca Linnaeus, 1758	Cetacea	Delphinidae	native migrant or resident	7 [24]
Spinner dolphin	Stenella longirostris Gray, 1828	Cetacea	Delphinidae	native migrant or resident	7
Short-beaked common dolphin	Delphinus delphis Linnaeus, 1758	Cetacea	Delphinidae	native migrant or resident	7
Common bottlenose dolphin	Tursiops truncatus Montagu, 1821	Cetacea	Delphinidae	possible migrant	7

Name	Species authority	Order	Family	Notes	Red List
Dugong	Dugong dugon Lacépède, 1799	Sirenia	Dugongidae	possible vagrant	7 [24]

• List of birds of Christmas Island
• List of mammals of the Cocos (Keeling) Islands

• "The IUCN Red List of Threatened Species: Mammals of Christmas Island". IUCN. 2001. Retrieved 22 May 2007. ^{[dead link‍]}
• "Mammal Species of the World". Smithsonian National Museum of Natural History. 2005. Archived from the original on 27 April 2007. Retrieved 22 May 2007.
• "Animal Diversity Web". University of Michigan Museum of Zoology. 1995–2006. Retrieved 22 May 2007.