Byron J.T. Morgan, Ph.D., is Emeritus Professor at the University of Kent. His research interests include applied statistics, biometry, statistical ecology, parameter redundancy, population dynamics and applications of Bayesian methods.Emily B. Dennis, Ph.D., is a Senior Ecological Statistician at Butterfly Conservation. Her research interests include modeling species abundance and distribution, citizen science data and biodiversity indicators, in particular with application to butterflies and moths.Stephen T. Buckland, Ph.D., is Emeritus Professor of Statistics at the University of St. Andrews. His research interests include modeling population dynamics, wildlife resource management, wildlife population assessment, distance sampling and biodiversity monitoring