Thursday, October 30, 2008
The Four Subspecies of the Common Eider in North America
The Hudson Bay Eider, note the band on it's leg...
Note: The new Downeast Duck Hunter site is over HERE...
Due to my proximity in Downeast Maine, I figure that almost 100% of my duck hunting takes place on the Atlantic Ocean. Within my bag exists the likes of the bufflehead, common goldeneye, old squaw, lesser scaup, merganser, butter bill scoter, surf scoter, white-winged scoter, mallard, black duck, and several other species. However, the duck that exists within my upmost passion for hunting is the common eider (somateria mollissima) and I have spent my entire life improving my practice to pursue these fantastic creatures. Recently, I have put a greater emphasis on understanding the common eider and exploring the science behind these interesting ducks. Since several of my high school students are very interested in duck hunting, I find myself explaining so much about my world and sometimes wondering if I could have answered their query better.
My education about the Northern eider came from a friend, Richard DiBiase, who guides in the Penobscot Bay region. Rich spoke of this Northern eider that would be brought in by the harsh Canadian winter. Before he could get a crack at them, they would have to get past me. I had always thought that all eiders were the same and now was constantly wondering about this Northern Eider. Before I knew it, I was reading and researching about the variety of common eider subspecies. Eventually, one of my students suggested that I write a research paper about my findings. I agreed and this is what I would like to share.
loral line- the black strip or line on an eider that begins just below the nostril and runs along the bill towards the black cap on top of the eiders head
lobes- part of the eider bill that separates towards the eye of the eider, varies in shape from subspecies to subspecies
Pacific Common Eider (somateria mollissima v-nigra)
Photo by Rene Pop
Range- Northwest Canada, Arctic Ocean, Alaska, Bering Strait, Russia, south to the Aleutian Islands
Notice the thickness of the black loral line running up the bill into the curved black cap
The largest and most brilliant of the common eiders, the Pacific common eider displays a vivid yellow orange bill that is defined by short, fine, pointed frontal lobes. It has a longer head with the greatest distance from the eye to the nostril of all common eiders. The Pacific Eider's bill has a fairly thick black loral line that extends to a deep curved black cap as the black emerges from the bill (loral line). In addition, the Pacific eider drake has a distinct black V on the chin unlike the other common eider races. Some have suggested that the head of the Pacific eider doesn't seem quite balanced.
The black V under the chin is unique to the Pacific Eider
Photo by Bruce MacTavish
Of particular note, this duck is the second most coveted in Alaskan waterfowl as it's cousin, the king eider, takes the top spot on the duck hunters list.
Hudson Bay Common Eider (Somateria mollissima sedentaria)
Range- Hudson and James Bay, Northern Canada (tundra region)
Named Mitia by the Inuit, the Hudson Bay eider is subject to a most demanding climate in the tundra region of Canada. Bred entirely in Hudson Bay, this subspecies is rarely acknowledged elsewhere but would be considered as an American eider if seen. They winter in a few isolated locations as they congregate in the ice free waters of Hudson Bay.
Because of the extreme climate and limited avenues for escape, these eiders continually live along the edge of the ice pack in order to access the water to feed. In addition, the Hudson Bay eider practices a survival tactic titled pullait. The Hudson Bay eider winters near areas of open water surrounded by sea ice called polynyas. In these small open areas, groups of eiders congregate and dive frequently for any available food. Due to the shear number of eiders, exhaled air meets the salt-water thin ice that rises to make a shallow dome. This naturally created shelter then exists for the eider to maintain their feeding patterns in these polynyas, which are rich in feed for all types of the food chain. Hudson Bay eider have become so reliant on polynyas for winter food they don't know how to migrate. Actually the scientific name sedentaria refers to the act of being sedentary or not moving around.
Arctic polynyas with Hudson Bay Eiders on the ice edge
However, there also exists a troubling act of nature by the ever-forming ice where Hudson Bay eiders become entrapped and perish. As the ice pack continues to form, the available areas for feeding become less prevalent. With limited access, areas become more crowded, the eiders create their own ice walls from frequent splashing. As this continues, the eiders become more desperate to escape and can not fly out of the hole. This then leads itself to several types of mortality. The eiders become easy prey, some drown, starve, or freeze as the hole continues to close. Most of these victims are immature eiders who haven't fled for safer waters. In some severely cold winters, there have been stories of thousands of eiders who have perished because of this phenomenon.
Through my research, I found a most interesting eider website produced by Joel Heath who seriously looks into the world of the Hudson Bay eider. His work is most amazing and I'm thankful for his dedication. I implore you to check out his site.
Surviving the Arctic Winter Research Site
If you want to see his movie trailer about his work, check this out
Trailer for Eider: Winter Survivor
American Eider (Somateria mollissima dresseri)
Notice how thin the black loral line is running up the side of the bill and the flatness of the the black cap against the white head
Photo by Bill Thompson
Range- Newfoundland, Labrador, New Brunswick, Nova Scotia, and the Northeastern United States
Identified by the slight protrusion of it's white sails contouring the white back, the American eider has a bill that varies in color from grey to olive to bright orange. The profile of the bill possesses large, broad, rounded frontal lobes that extend closer to the eye and it's head offers a more extensive translucent green extending along the lower back of the black cap. The black strip (loral line) between the white and the frontal lobe is the thinnest amongst of the eider subspecies.
Notice the profile of the bill and the rounded frontal lobes by the eye
Maine supports part of the Atlantic population of common eiders and is the only major eider breeding contiguous state with an abundance of uninhabited smaller islands.
The two main focus points I have chosen for this subspecies were the challenges of decreasing numbers over time and the feeding patterns to which I can relate to an article I published on Duck Hunting Chat.
During the 1800's and early 1900's, the American eider numbers decreased throughout coastal Maine for a variety of reasons. Offshore islands were becoming occupied by people for fishing and farming purposes. This human disturbance affected the eider's ability to breed and also increased gull predation as nest desertion became more prominent. Egg collecting and hunting without regulations also caused a significant decline. Eider down, famous for it's insulating properties, was in high demand for featherbeds and pillows. With the advent of hunting regulations and the abandonment of many coastal islands as some of the fishing industries declined in participation, the Maine eider population did in fact increase.
Factors such as avian predation, starvation, drowning, and human disturbance all tend to act interdependently to challenge the survival possibilities of the young ducklings. Organizations such as the Nature Conservancy, Ducks Unlimited, and other societies have put forth much effort to ensure that breeding habit remains free of development.
The feeding patterns of the eider are quite unique in that the majority of their dietary intake consists of animal matter. Primarily feeding on marine invertebrates, the eider will dive up to depths of 40 feet searching for blue mussels, sea urchins, periwinkles, and green crabs. Of notice, it has been determined that these ducks present a habitual feeding pattern coinciding with tidal level at mean low water. This is when the eiders can more easily pursue the above listed marine species.
For a video by Joel Heath showing a feeding eider click below
Eider Diving for Feed
Northern Eider (Somateria mollissima borealis)
Photo by Dick Newell
Notice how the lobes of the Northern eider aren't as rounded as the American Eider
Photo by Killian Mullarney
Notice the sails on the Northern Eider's back
Photo by Paul Kelly
Through my research, this subspecies provided the least information. However, it is quite apparent that one must take time to conisider the physical attributes to distinguish this arctic species against it's cousins southward.
The bill of the Northern Eider which frequents Maine in the late winter tends to exhibit a bright yellow orange bill base as evident of the Greenland and Northeastern Canadian residents.
From experience, these northern eiders are larger than their American cousins and sport a more fantastically brighter bill (a more vibrant yellow) with a less pronounced frontal lobe. The American eider has a much more rounded feature where the bill separates at the wedge of the black cap. In addition to the differences of the bill and size, the sails of the Northern eider are more apparent as the scapulars tend to be more exposed at rest as opposed to a more reserved appearance from the American eider. Finally, the loral line is thicker than the American eider (where the black begins by the nostril) and the black cap that exists on all subspecies of eider is relatively straight and uniform from the perspective of the Norther eider.
Throughout the remainder of my eider hunting career, I'll be sure to look for any interesting encounters. I'm sure of my taking of the American and Northern eider, but will be curious if either a Pacific or Hudson Bay eider find their way Downeast. However, when I do, the research and time taken will prove quite beneficial for proper identification.
Eiders in Ireland- Rare forms worth finding
Martin Garner & Wilton Farrelly
Habitat Suitability Index Model: Americian Eider (Breeding) Biological Report 2/1988
Arlene K. Blumton
Ray B. Owen, Jr.
William B. Krohn
Eider Duck Underwater Video
Joel Heath, 2002