U.S. Department of Agriculture: Animal and Plant Health Inspection Service


Date of this Version

January 2003


Double-crested Cormorant (Phohoiornx audus) numbers are increasing throughout eastern North America. We compared variation for five portions of mtDNA to determine if genetic differences existed among portions of the breeding range that would need to be considered when formulating management programs. Sequences for four mtDNA regions were identical across sample locations: frequencies of two haplotpes of the mitochondria1 Control Region were similar across sampling locations. There is no evidence of restricted gene flow among breeding areas, or between subspecies with different migratory patterns.