Audubon Core

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Warning: This is not the current version of this document. It is kept for archival purposes. For up-to-date information, go to

The Audubon Core is a set of vocabularies designed to represent metadata for biodiversity multimedia resources and collections. These vocabularies aim to represent information that will help to determine whether a particular resource or collection will be fit for some particular biodiversity science application before acquiring the media. Among others, the vocabularies address such concerns as the management of the media and collections, descriptions of their content, their taxonomic, geographic, and temporal coverage, and the appropriate ways to retrieve, attribute and reproduce them. Contributors: Robert A. Morris, Vijay Barve, Mihail Carausu, Vishwas Chavan, Jose Cuadra, Chris Freeland, Gregor Hagedorn, Patrick Leary, Dimitry Mozzherin, Annette Olson, Greg Riccardi, Ivan Teage.

See also: the normative documents Audubon Core Structure and Audubon Core Term List, the Audubon Core Non Normative Document and the Audubon Core Implementations (non-normative). Issue reports and resolutions are at the Audubon Core Issue Tracker.


The Audubon Core Multimedia Resources Metadata schema (“AC schema”, or simply “AC”) is a set of metadata vocabularies for describing biodiversity-related multimedia resources and collections. The specification is independent of how these vocabularies may be represented for machine use.

Multimedia Resources are digital or physical artifacts which normally comprise more than text. These include pictures, artwork, drawings, photographs, sound, video, animations, presentation materials, and interactive online media including, e.g., identification tools. A multimedia collection is an assemblage of such objects, whether curated or not, and whether electronically accessible or not. For the purposes of this document we regard a collection of multimedia resources itself as a ‘multimedia resource’. Wherever discussion or specification can apply only to a collection or only to a single media resource, we say so explicitly.

Multimedia descriptions are digital records that document underlying multimedia resources or collections. AC is focused on biodiversity-related multimedia resources. It shares terminology and concerns with many well-known and important standards for describing access to resources such as Dublin Core (DC), Darwin Core (DwC), the Adobe Extensible Metadata Platform (XMP), the International Press and Telecommunications Council (IPTC), the Metadata Working Group (MWG) schema, the Natural Collections Schema (NCD), and others. Where there is an exact match to the usage of such standards, AC adopts their identifiers and definitions. Many collections of biodiversity multimedia already have descriptions of their media expressed in DwC or DC. By using those vocabularies where suitable, AC particularly intends to make it easy for such collections to reuse their existing descriptions, augmented where necessary by other terms.

Audubon Core Terms

An Audubon Core record is a description of a multimedia resource using the Audubon Core terms. Two kinds of terms are specified by AC: record-level terms and access-level terms. Record-level terms apply to the media resource being described. Almost all terms are record-level terms. One such term, hasServiceAccessPoint plays a special role in helping to retrieve the resource that the record describes. A multimedia resource may have more than one hasServiceAccessPoint, each of which provides values of one or more access-level terms. The access-level terms document such things as a web address at which a digital representation of the resource can be retrieved, the size of such a retrieved object, etc. An Audubon Core record is thus a description using a set of terms that conforms to the normative documents, and contains at least the four mandatory terms, which provide an identifier, a resource type, the language of the description, and copyright information. Every such record describes a single multimedia resource (possibly including a Collection). The identifier may have been assigned to the resource by an external authority or by the provider of the record. Strictly speaking, the identifier is required only for Collections, but is strongly recommended in general.

Every Audubon Core term has a plain text Name, a term identifier and a plain text normative Definition. Term identifiers conform to the Universal Resource Identifier (URI) specification. Typically these identifiers have a form familiar to browser users as the addresses of web pages, beginning with "http://". Informally, one may understand this thusly: an http URI has the syntax of a web address, but there is no expectation that putting it in a web browser will result in any information being returned to the browser, and if it does, the return may have no relevance.

Because http URIs are rather lengthy, AC documents follow a standard practice of introducing a short prefix comprising a "namespace qualifier" separated by a colon from a mnemonic name closely related to the term's Name. The namespace of the roughly 50% of the terms that are borrowed from other vocabularies is the namespace of the original. The namespace of denovo AC terms is In the Audubon Core Term List, each term entry has a row with the term name. Following the practice of the Darwin Core terms, this term name is generally an "unqualified name" preceded by a widely accepted prefix designating an abbreviation for the namespace. The result is known as a qualified name. For example the normative wiki documentation for the borrowed term dcterms:identifier has URI The first part, "" corresponds to the namespace. Most of the URIs for terms borrowed from external vocabularies do in fact produce relevant documentation for that external standard when used as a web page URL. Sometimes it is not precise because the documentation is a PDF document and several (different!) URIs might apparently apparently lead to the same place.


The normative AC Term List and Audubon Core Structure documents represent a data model. For actual use of Audubon Core, it is necessary to select an implementation, preferably one with some status designated by TDWG. A list of known implementations is at Audubon Core Implementations


[ACISS] AC issue tracker
[DCMIU] Dublin Core User Guide
[DWCCP] Darwin Core change policy; also followed by AC
[IMPLS] Known AC implementations
[STRCT] Normative introduction to AC structure
[TERMS] Normative Term List
[OFFLN] Non-normative AC documents
[RDFAC] Example simple RDF Implementation

This page is a Non-normative introduction to the Audubon Core Multimedia Metadata specification.

See also: Discovery and Publishing of Primary Biodiversity Data associated with Multimedia Resources: The Audubon Core Strategies and Approaches. R. Morris et al., Biodiversity Informatics, 8, jul. 2013.