Skip to main content
U.S. flag

An official website of the United States government

Unmarked: An R package for fitting hierarchical models of wildlife occurrence and abundance

January 1, 2011

Ecological research uses data collection techniques that are prone to substantial and unique types of measurement error to address scientific questions about species abundance and distribution. These data collection schemes include a number of survey methods in which unmarked individuals are counted, or determined to be present, at spatially- referenced sites. Examples include site occupancy sampling, repeated counts, distance sampling, removal sampling, and double observer sampling. To appropriately analyze these data, hierarchical models have been developed to separately model explanatory variables of both a latent abundance or occurrence process and a conditional detection process. Because these models have a straightforward interpretation paralleling mechanisms under which the data arose, they have recently gained immense popularity. The common hierarchical structure of these models is well-suited for a unified modeling interface. The R package unmarked provides such a unified modeling framework, including tools for data exploration, model fitting, model criticism, post-hoc analysis, and model comparison.

Publication Year 2011
Title Unmarked: An R package for fitting hierarchical models of wildlife occurrence and abundance
DOI 10.18637/jss.v043.i10
Authors Ian J. Fiske, Richard B. Chandler
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Statistical Software
Index ID 70006019
Record Source USGS Publications Warehouse
USGS Organization Patuxent Wildlife Research Center
Was this page helpful?