Data deficient

A data deficient species is one which has been categorized by the International Union for Conservation of Nature as offering insufficient information for a proper assessment of conservation.

Qualifications

DD species may have been extensively studied, but in some cases little or no information is available on the abundance and distribution of the species. It can also indicate uncertainty about the taxonomic classification of an organism; for example, the IUCN classifies the orca as "data deficient" because of the likelihood that two or more types of the whale are separate species.
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".