The Corvids Literature Database--500 years of ornithological research from a crow's perspective.

Corvids (Corvidae) play a major role in ornithological research. Because of their worldwide distribution, diversity and adaptiveness, they have been studied extensively. The aim of the Corvids Literature Database (CLD, http://www.corvids.de/cld) is to record all publications (citation format) on all extant and extinct Crows, Ravens, Jays and Magpies worldwide and tag them with specific keywords making them available for researchers worldwide. The self-maintained project started in 2006 and today comprises 8000 articles, spanning almost 500 years. The CLD covers publications from 164 countries, written in 36 languages and published by 8026 authors in 1503 journals (plus books, theses and other publications). Forty-nine percent of all records are available online as full-text documents or deposited in the physical CLD archive. The CLD contains 442 original corvid descriptions. Here, we present a metadata assessment of articles recorded in the CLD including a gap analysis and prospects for future research. Database URL: http://www.corvids.de/cld.