This important piece of any dataset helps analysts determine absence or lack of detection.  For example, if you download a dataset for a single species, you might want not only the positive observations of the species, but also the data representing when birds were sampled in a given area and the species was not detected.

How to get Sampling Event Data

The sampling event data are available using the Data Download Tool. Follow the same instructions for using this tool found on the right hand column of the page, but select "Sampling Event Data" from the options in Download Data Type.  When downloading sampling event data you can only specify a geographic region and date range; leave the species selection blank.  Make sure that your date range and geographic region are the same as those you chose when downloading your dataset of positive observations.

How to use Sampling Event Data

Some work will need to be done on the back-end by your analysts to combine the sampling event data with the positive observations dataset.  The sampling event data contain ALL sampling events for the given date range and geographic region, not just those failed to detect the species.  Thus, you'll need to merge the two tables so that the sampling event IDs from the positive observation dataset are only represented once in the combined table.  This can be done easily using Microsoft Access or other commericial database programs.  The resulting file should contain all the positive observations of the species in question, as well as a separate row containing the sampling data for each time a survey was conducted in the region and the species was not detected.