From the 2-gram bumblebee bat to the 150-ton blue whale, the Mammal Diversity Database catalogs all 6,600+ known species — and the list keeps growing. This is the taxonomy that conservation policy depends on.
You cannot protect what you have not named. This deceptively simple principle sits at the heart of the Mammal Diversity Database, a continuously updated catalog of every known mammal species on Earth. Maintained by the American Society of Mammalogists — the world's oldest professional society dedicated to the study of mammals — the MDD has become the authoritative reference for mammalian taxonomy, used by the IUCN Red List, the Convention on Biological Diversity, and national wildlife agencies worldwide. When a government asks how many endangered species inhabit a proposed mining concession, the taxonomy underlying that answer almost certainly traces back to this database.
The numbers are staggering in their specificity. As of the latest release, the MDD recognizes over 6,600 species of mammals across 27 orders, 167 families, and more than 1,300 genera. But the database is not static — it is a living document that absorbs the constant churn of taxonomic science. Each year, roughly 20 to 25 new mammal species are formally described, while existing species are split, lumped, or reclassified as molecular phylogenetics reveals hidden diversity or collapses artificial distinctions. The MDD tracks every one of these changes, providing a versioned, citable record that researchers and policymakers can pin their analyses to.
What makes the MDD irreplaceable is not just its comprehensiveness but its curation. Unlike automated aggregations that scrape names from literature, every taxonomic decision in the MDD has been reviewed by expert mammalogists. The database records not only the accepted name for each species but the synonyms, the original description, the type locality, distribution notes, and the IUCN conservation status. With 62,000 views and 44,000 downloads, it has become foundational infrastructure for biodiversity science — the denominator against which extinction rates, protected area coverage, and evolutionary distinctiveness are measured. In a century where mammals face unprecedented habitat loss, climate disruption, and overexploitation, this catalog is both a scientific achievement and a conservation imperative: the definitive list of what we stand to lose.
Number of recognized species in the largest mammalian orders, showing that rodents and bats together account for over 60% of all mammal diversity
Every protected area assessment, extinction risk analysis, and biodiversity target depends on accurate species counts. The MDD provides the denominator — without it, we cannot measure what we are losing or whether our efforts are working.
By tracking taxonomic revisions driven by molecular phylogenetics, the MDD captures the ongoing discovery of cryptic species and the reshaping of mammalian evolutionary trees in real time.
National endangered species lists, CITES appendices, and international biodiversity frameworks all depend on standardized taxonomy. The MDD provides the authoritative species list that these legal instruments reference.
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