Evaluating the contribution of wading bird populations to avian biodiversity and wildlife managers' ability to maintain viable wading bird populations requires accurate information on population levels and trends. Wading bird population surveys often use multiple observers in single or over multiple years, but inter-observer variability is seldom evaluated. We conducted a study to test for significant inter-observer variability among experienced biologists and to determine the impact of variability on biologists' ability to accurately survey colonies and to monitor statewide trends in colonial wading bird populations. Interobserver variability was not significantly diiferent, but statistical power was low. Based on the results of this study, we believe that an analysis of inter-observer variability should be a component of any wading bird survey that includes multiple observers in single or over multiple years.