The primary method for estimating species populations is the use of sampling techniques, including direct counts, mark-recapture, and statistical models. Direct counts involve observing and recording individuals in a defined area, while mark-recapture allows researchers to estimate population size by capturing, marking, and releasing individuals back into the wild. Statistical models, such as linear regression, help analyze data collected from these methods to make predictions about population dynamics. Accurate estimations are crucial for understanding species health and informing conservation management strategies.