TRIM (TRends and Indices for Monitoring data) is used to determine species‘ population trends. It allows for missing counts using estimation and yields yearly indices and standard errors using Poisson regression. TRIM is a freeware program developed by Statistics Netherlands in the framework of wildlife statistics. PECBMS uses a set of three R scripts called RTRIM-shell, which is developed by Statistics Netherlands, using the RTRIM package to calculate national species indices. Read more.
BirdSTATs (The Species Trends Analysis Tool for birds) is an open-source Microsoft Access database for preparing and statistical analysis of bird counts data in a standardized way. The BirdSTATs tool is programmed to use and automatically run the program TRIM (TRends and Indices for Monitoring data) in batch mode to perform the statistical analysis for a series of bird counts in the dataset. In this way, it is suitable for all European countries participating in the Pan European Common Bird Monitoring Scheme (PECBMS). Using the BirdSTATs tool results in standardized indices used as subsets by the PECBMS to calculate overarching European wild bird indicators. Read more.
The updated version of the BirdSTATs, released in March 2016, can be downloaded here (3.2 MB).
The software and further information to undertake these analyses are freely available at distancesampling.org
Distance sampling considers that the number of birds seen or heard declines with distance from the observer. The shape of this decline, the distance function, differs among species, among observers, and, importantly, among habitats. Distance sampling models the ‘distance function’ and estimates density taking into account both the birds observed and those present but not detected.
More advanced software, such as the programs MARK, BROWNIE, CAPTURE, ESTIMATE, OREMARK, RELEASE, and radio-tracking programs, are available on the page of professor Gary C. White, Colorado State University.