How many mammal species are there now? Updates and trends in taxonomic, nomenclatural, and geographic knowledge Author Burgin, Connor J Department of Biology, University of New Mexico, Albuquerque, NM 87106, United States connorjburgin@gmail.com Author Zijlstra, Jelle S Hesperomys Project, Orinda, CA 94563, United States Author Becker, Madeleine A Smithsonian-Mason School of Conservation, Smithsonian Institution and George Mason University, Front Royal, VA 22630, United States & Center for Conservation Genomics, Smithsonian’s National Zoo and Conservation Biology Institute, Washington, DC 20008, United States & College of Science, George Mason University, Fairfax, VA 22030, United States Author Handika, Heru Museum of Natural Science and Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, United States Author Alston, Jesse M School of Natural Resources and the Environment, University of Arizona, Tucson, AZ 85721, United States Author Widness, Jane Department of Anthropology, Yale University, New Haven, CT 06511, United States Author Liphardt, Schuyler Division of Biological Sciences, University of Montana, Missoula, MT 59812, United States Author Huckaby, David G Department of Biological Sciences, California State University, Long Beach, Long Beach, CA 90840 - 3702, United States Author Upham, Nathan S School of Life Sciences, Arizona State University, Tempe, AZ 85287, United States nathan.upham@asu.edu text Journal of Mammalogy 2025 2025-09-14 106 5 1082 1117 https://doi.org/10.1093/jmammal/gyaf047 journal article 10.1093/jmammal/gyaf047 PMC12526941 41103548 17381510

Table 1. Taxon counts for major mammalian taxonomic compendia since 1980 (see Fig. 1 for graphical representation of species totals for each, except IUCN totals), including the 3 editions of Corbet and Hill’s (C&H) A World List of Mammalian Species; editions 4 through 6 of Walker’s Mammals of the World (WMW); Anderson and Jones’ Orders and Families of Recent Mammals of the World (A&J); Duff and Lawson’s Mammals of the World: A Checklist (D&L); 3 editions of the Mammal Species of the World (MSW); Illustrated Checklist of the Mammals of the World (CMW); International Union for the Conservation of Nature (IUCN) 2008 and 2024-1 listings; and 2 major versions of the Mammal Diversity Database (MDD1 and MDD2).

Taxa	C&H1 1980	MSW1 1982	WMW4 1983	A&J 1984	C&H2 1986	C&H3 1991	WMW5 1991	MSW2 1993
aIUCN 2008 totals based on Schipper et al. (2008). bLists 4,007 species, but we identified 2 duplicates (what is now Brucepattersonius iheringi is listed under both Microxus and Oxymycterus, and Prosciurillus leucomus is listed under both Prosciurillus and Callosciurus). cTotal provided in Solari and Baker (2007) and used in Burgin et al. (2018) was found to be incorrect while counting the MSW2 species total and we here provide a corrected total. dIncludes species classified as Extinct in the Wild and does not include humans. eThe IUCN does not assess domestic species.
Species	4,005b	4,170	4,151	4,199	4,231	4,336	4,444	4,629c
Wild extant	N A	N A	N A	N A	N A	N A	N A	N A
Recently extinct	N A	N A	N A	N A	N A	N A	N A	N A
Domestic	N A	N A	N A	N A	N A	N A	N A	N A
Genera	1,014	1,033	1,017	1,057	1,055	1,066	1,116	1,135
Families	129	135	133	131	132	131	135	132
Orders	21	20	20	21	20	21	21	26
Taxa	WMW6 1999	D&L 2004	MSW3 2005	IUCN 2008 a	MDD1 2018	CMW 2020	IUCN 2024	MDD2 2024
Species	4,809	5,115	5,416	5,489	6,495	6,554	5,983	6,753
Wild extant	N A	N A	5,338	5,410d	6,382	6,451	5,899d	6,629
Recently extinct	N A	N A	75	79	96	103	84	113
Domestic	N A	N A	3	0e	17	20	0e	17
Genera	1,192	1,117	1,230	1,241	1,316	1,343	1,308	1,353
Families	146	128	153	156	166	167	164	167
Orders	28	27	29	27	27	27	27	27