PSSS Protocol Training Video 

Audubon

Seattle

Using a ruler and a compass, surveyors gather data that allows scientists to estimate bird density through ‘distance sampling’. Simply counting the number of birds in a given location is a simpler approach, but it forces scientists to assume that all birds are detected by observers. In reality, detection of any species declines with the distance from the observer: poor sighting conditions, quality of observing equipment, and observer inexperience all contribute to declining detection likelihood as distance increases. Distance sampling provides a robust approach to estimating density and allow for calculation of less biased density estimates.