• Pacific Loon

    Common NamePacific Loon
    Scientific NameGavia pacifica
    Type of ReportRare Species
    Date of Observation10/29/2017
    Number Observed1
    Reporting Observer's NameMichael Locher
    Mailing Address71 Hockanum Road
    Hadley, MA 01035
    United States
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    EmailEmail hidden; Javascript is required.
    Date Completed10/30/2017
    Latitude of Observation44.1829° N
    Longitude of Observation73.3503° W
    Place NameButton Bay, Lake Champlain
    TownshipFerrisburgh
    CountyAddison
    Vermont eBird Checklist URLebird.org
    Time of Day02:30 PM
    Length of Time Observed30 minutes
    Maximum Estimated Distance from Bird (in feet)1000 feet (?)
    Minimum Estimated Distance from Bird (in feet)1500 feet (?)
    Noteworthy Weather Conditions

    Overcast and drizzly.

    Optical Equipment Used for Observation

    Swarovski 10x42 binoculars; Swarovski 20-60 spotting scope.

    Observer’s Previous Acquaintance With This or Similar Species

    I have seen a few Pacific Loons on a trip to Alaska. I am primarily familiar with Common Loons (Summer and winter plumage) because they are resident where I live, and Red-throated Loons (primarily winter plumage) which I see typically on trips to coastal Massachusetts in the winter.

    I certify that that attachments included with this report were captured during this observation event​​.
    Description of Habitat

    Lake Champlain, open water. In a group with 5 Common Loons and 2 Ring-billed Gulls.

    Behaviors Observed

    The bird was actively feeding when we first saw it, and continued through the half an hour we studied it. At one point nearby Ring-billed Gulls seemed to be harassing it as it rose to the surface (although they left the larger Common Loons alone).

    Description of Vocalizations

    None.

    Verbal Narrative & Description of Observation

    As stated above, the bird was actively feeding for the entire 30 minutes of observation, and afforded only brief views. At first it was alone, and stood out as a small, dark, slender-necked loon. As time went on a school of small fish must have been in the area, and two Ring-billed Gulls joined it. The gulls appeared to harass the loon at times, striking at it as it rose to the surface. Soon five Common Loons joined the group, allowing comparison.
    Unfortunately, the bird never sat quietly on the water. It would surface for a second or two, then dive again, making observation difficult.

    Relative Size & Shape

    The bird was clearly a loon in shape, although it was much smaller and more slender than the surrounding Common Loons.

    Head

    The bird had a very dark head, and the black mask covered the eye. The cheeks and throat were white (I did not see a "chinstrap"). Once or twice I got a look that seemed to indicate that the bird was darkest through the eye, and slightly lighter on top of the head.
    The neck was bright white, and there was a strong vertical demarkation between this white and the black feathering of the sides of the throat and the back of the neck.

    Feet & Bill

    I could not see the feet. The bill was dark (gray or black), and appeared to be less bulky than that of a Common Loon, but not so slender as a Red-throated Loon's. It did not hold its bill at an upward angle.

    Upper Back

    The upper back was very dark/black; much darker than the surrounding Common Loons.

    Lower Back & Rump

    The lower back was also very dark/black. (I can't say that I saw the rump.)

    Wings

    It briefly flared its wings when diving, and they appeared solid black.

    Breast, Belly, Flanks, Under Tail Coverts

    When the bird (briefly) sat in the water, I saw no white except on the throat and upper breast. When it dove, the belly appeared bright white in contrast to dark upper feathers. I could not see the color of the undertail coverts as it dove.

    Tail

    I didn't look at the tail enough to give any description.

    IMPORTANT: What similar species were eliminated when making the identification and how was this bird different?

    The two main candidates for similar species are Common Loon and Red-throated Loon.
    The bird was much smaller than the surrounding Common Loons (and they were within several feet for easy comparison). Additionally, the bill was less bulky, the neck and body appeared to be much more slender, the back was very dark gray/black (not light gray or mottled), and the dark feathers of the neck showed no hint of the paler "spike" that Common Loons frequently have.
    This bird did not have the very slender upwardly-angled bill of a Red-throated Loon. The black of the head covered the eye, and the white of the cheek was limited, eliminating an adult non-breeding Red-throated Loon. The throat on the bird was bright white, unlike the juvenile Red-throated Loon, and in my experience, in winter plumage, Red-throated Loons appear lighter than Common Loons on the water. This bird was darker.
    Horned Grebes (which were nearby) don't have big enough bills, Red-necked Grebes don't have enough white on the throat. Other grebes have bills that are too slender, and other loons (Arctic) seem even more unlikely than Pacific.

    Other Notes & Comments

    I thought at the time that it seem closest to the juvenile plumage, because the juveniles don't show the chinstrap as strongly as adults, and their crowns may be lighter.

    This report was written from notes taken:Written from Memory

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