Resources related to Abundance

Sex-biased winter philopatry in Harlequin Ducks: are waterfowl really an exception to the rule?

Many birds species exhibit a resource based mating system where males defend breeding territories. This mating system is thought to have lead to male-biased philopatry as male birds are better able to defend familiar territories. In contrast, female waterfowl are more likely than males to return to their breeding grounds. Waterfowl are the exception because males cannot economically defend breeding territories and a mate-defense system has evolved. However, waterfowl pair in the winter.

Modeling The Population Demography Of Harlequin Ducks

Population demography models are valuable tools in detecting population trends and identifying crucial components in the life history of a species. They are also useful in determining critical research needs to estimate needed parameters. A matrix-based p opulation model was expanded for Harlequin Ducks (Histrionicus histrionicus) originally developed by Goudie et al. (1994, Trans. North Am. Wildl. Nat. Resour. Conf. 59:27- 49.).

Environmental Health Issues

We review nesting sea duck population declines in Alaska during recent decades and explore the possibility that contaminants may be implicated. Aerial surveys of the surf scoter (Melanitta perspicillata) , white-winged scoter (M. fusca) , black scoter (M. nigra) , oldsquaw (Clangula hyemalis) , spectacled eider (Somateria fischeri) , and Steller's eider (Polysticta stelleri) show long-term breeding population declines, especially the latter three species. The spectacled eider was recently classified threatened under the Endangered Species Act.

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http://ehpnet1.niehs.nih.gov/docs/1995/Suppl-4/henny.html

Parasitism, Population Dynamics And Hybridization In Cavity- Nesting Seaducks

Intraspecific and interspecific brood parasitism occur frequently in waterfowl. We examine the consequences of these behaviors to the population dynamics of Barrow's and Common Goldeneyes during a 10 year study period in central British Columbia. The frequency of parasitism was significantly related to population density and to the availability of nest sites. High levels of parasitism, in turn, resulted in reduced reproductive success of females.

Philopatry In Nesting Adult Female Spectacled Eiders At Kigigak Island, Yukon Delta National Wildlife Refuge, Alaska

In response to the dramatic decline of the species (early 1970's to 1990's) on the Yukon-Kuskokwim Delta, I conducted a nesting ecology study on spectacled eiders (Somateria fischeri) at Kigigak Island from 1992-1996. The Kigigak Island population has had relatively high nest success between 1992-1996 (92%, 63%, 70%, 64%, and 82%, respectively). More than 50% of the nesting females have been marked (n=161). Preliminary results show that 70% of the marked females have returned to nest at least once following their banding year and that 52% returned at least two consecutive years.

Population Dynamics Of Spectacled Eiders On The Yukon- Kuskokwim Delta, Alaska

Spectacled Eider (Somateria fischeri) populations in western Alaska have declined precipitously since the late 1970's. Subsequently, the species was listed as threatened in 1993. To investigate the potential causes of the decline, we developed a deterministic model of Spectacled Eider population dynamics based on demographic data we collected on the Yukon-Kuskokwim Delta, Alaska, from 1991-1996. The model incorporated estimates of nest success, clutch size at hatch, duckling survival, age of first reproduction, and adult female survival collected at a two locations.

Mitochondrial DNA control region sequence variation in Common Eiders reveals extensive mixing of subspecies

We sequenced a hypervariable 319 bp portion of the control region of mitochondrial DNA in five subspecies of Common Eiders (Somateria mollissima) and an outgroup sample of King Eiders (S. spectabilis). Variation was found at 71 sites (22%), which defined 56 haplotypes in the total sample. A genealogical tree relating the haplotypes revealed three major clades, but with the exception of Common Eiders (S. v-nigra) from Alaska, they did not correspond with putative subspecies identities.

Status of the common eider (Somateria mollissima) in New Brunswick

In 1995 we conducted a pilot study of brood ecology of the Common Eider Somateria mollissima with specific reference to movements, habitat use and behaviour of both adult females and ducklings on the Wolves Archipelago in the Bay of Fundy. Information generated from this colony, particularly recruitment, over the next 3 years was to be used in conjunction with information collected from other breeding colonies to develop a model of the role of post-hatch ecology in the demographics of Common Eiders in the Bay of Fundy.

The effect of body condition on subsequent creche attendance in Common Eiders (Somateria mollissima)

Creches are groups containing any number of adult female(s) and duckling(s), two or more of which are parentally unrelated. Several authors have suggested that the body condition of ducks is a determining factor in parental care and that females in poor condition more readily abandon their young. In 1997 and 1998, 285 adult female Common Eiders breeding on Green Island were captured and nasal tagged. Our objective was to examine the relationship between adult female condition, using multiple measures of body size, and subsequent membership in creche.

Importance Of Common Eiders In An Intertidal Community: Predation, Disturbance, And Indirect Effects

Intertidal community ecology is an extremely well developed field. However, sea ducks are frequently neglected in intertidal community studies, because they are viewed as transient or not sufficiently numerous to have an effect. This may be a mistake, because recent work with other aquatic birds indicates that they can be very important in structuring communities. We examined the importance of Common Eiders (Somateria mollissima) as predators in an intertidal invertebrate community in Passamaquoddy Bay, New Brunswick, Canada.

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