COSEWIC assessment and status report on the eastern yellow-bellied racer, Coluber constrictor flaviventris, and the western yellow-bellied racer, Coluber constrictor mormon, in Canada

'Since the previous status report (COSEWIC 2004), new survey information has helped refine distributions of both the Eastern and Western Yellow-bellied Racers, and several previously unknown den sites have been documented. New molecular work completed on 150 Eastern Yellow-bellied Racers from two river valleys (Frenchman and the Big Muddy river valleys) indicates that there may be several genetically distinct subpopulations in Canada. A major terrain slump event occurred in the spring of 2011 at the largest known den site of the Eastern Yellow-bellied Racer and displaced or killed a potentially significant but unknown proportion of racers at the den. No new information exists on population size and trends of Western Yellow-bellied Racers, but threats have been assessed and remain substantial”--Preface (p. xvi).