Differentation and Interchange of Harlequin Duck Populations Within the North Pacific

Goatcher, Buddy; Zwiefelhofer, Denny; Lanctot, Richard; Talbot, Sandy; Pierson, Barbara; Esler, Dan; Scribner, Kim; US Fish and Wildlife Service

Concerns about constraints to harlequin duck (Hzsirionicus histrionicus)p opulation recovery following the Exxon Vuldez oil spill led biologists to ask whether birds in different molting and wintering areas belong to genetically distinct and, thus, demographically independent population segments. Because of the lack of direct observations of movements among marine areas, genetic markers, which differed in mode of inheritance (two sex-linked Z-specific microsatellite loci, four biparentally inherited microsatellite loci and maternally inherited mitochondrial deoxyribonucleic acid sequences), were used to evaluate the degree of genetic differentiation among wintering areas within Prince William Sound, Alaska Peninsula (Katmai National Park) and Kodiak Archipelago (Kodiak National Wildlife Refuge). We also used colored leg bands to detect population interchange within and among these regions. Our genetic results show that differences in genotype frequencies among wintering locations within Alaska were low and non significant for all three classes of markers. An analysis of genetic samples collected throughout the West Coast of North America revealed significant structuring at larger geographic scales. No interchange of banded birds was observed among regions and movements within regions were uncommon. Our failure to detect movements in banded birds may have been a function of the short duration sotfu dy (e.g., two years of banding with one year of recoveries and resightings), whereas our genetic analyses reflected demographic characteristics acquired over greater time scales. We conclude harlequin ducks are likely to recolonize or enhance populations in areas recovering from environmental damage via emigration of birds from unaffected areas, Our demographic results, and those from other studies, suggest that the levels of movements are low, and that population recovery by emigration may be a long-term process.