A data deficient (DD) species is one which has been categorized by the International Union for Conservation of Nature (IUCN) as offering insufficient information for a proper assessment of conservation status to be made. This does not necessarily indicate that the species has not been extensively studied; but it does indicate that little or no information is available on the abundance and distribution of the species.
Comparison of Red list classes above
and NatureServe status below
The IUCN recommends that care be taken to avoid classing species as "data deficient" when the absence of records may indicate dangerously low abundance: "If the range of a taxon is suspected to be relatively circumscribed, if a considerable period of time has elapsed since the last record of the taxon, threatened status may well be justified" (see also precautionary principle).
- IUCN Red List data deficient species
- List of data deficient amphibians
- IUCN Red List data deficient species (Annelida)
- List of data deficient arthropods
- List of data deficient birds
- IUCN Red List data deficient species (Cnidaria)
- List of data deficient fishes
- List of data deficient insects
- List of data deficient invertebrates
- List of data deficient mammals
- List of data deficient molluscs
- List of data deficient reptiles
- "The Categories," in IUCN (1994).
- IUCN (2001). "2001 Categories & Criteria (version 3.1)". 2014 IUCN Red List. Retrieved 2014-08-26.