Subject: Re Re: Grebes, grebes, grebes...
Date: Sep 23 22:38:42 1998
From: Steve Hallstrom - toltfarm at jps.net


Bonnie,

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Steve Hallstrom

> Date: Wed, 23 Sep 1998 13:04:38 -0700
> To: TWEETERS at u.washington.edu
> From: Bonnie Stout <bestout at sfu.ca>
> Subject: Grebes, grebes, grebes...
> Mime-Version: 1.0
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>
> Hello Tweeters!
>
> I am a birder and graduate student researching grebes (Red-necked, Horned,
> and Western). I am hoping to enlist your help in my quest to locate
> important moult and wintering sites of grebes on the Wash/BC coast.
>
> My work so far has identified Boundary Bay as a major moult site for
> Red-necked and Western Grebes. Yesterday, for example, I counted 2,576
> Red-necked Grebes in Boundary Bay (1,481 from Crescent Beach, BC; 283 from
> "1001 steps" [Surrey, BC]; and 812 from Lily Point, Point Roberts, WA).
> There are also at least as many Western Grebes. Though a few thousand
> Western Grebes is not a terribly impressive figure for this gregarious
> species, the number of Red-necked Grebes using Boundary Bay is significant.
> Smaller numbers of Horned Grebes (140+) are also now present.
>
> I observed similar numbers last fall, and the grebes are consistent from
> year to year in their use of specific sites within Boundary Bay. The
> Red-necked and Western Grebes are using Boundary Bay during the fall
> (pre-basic) moult, which occurs anytime from August-mid October. During
> this moult the grebes have simultaneous moult of flight feathers, rendering
> them flightless for at least 3 weeks. I have been able to confirm that
> these birds are undergoing the wing-moult in Boundary Bay by watching them
> when they flap their wings. A bird which has recently molted its flight
> feathers is quite obvious as the wings are a shadow of their former selves,
> appearing very stubby! We know very little about grebes during the
> non-breeding seasons, especially during moult - a time when they are quite
> vulnerable. Interestingly, the grebes appear to clear out of Boundary Bay
> after completion of moult - with numbers falling off rapidly in October and
> not recovering until spring migrants move back into the area. I have no
> idea where the Boundary Bay grebes spend the winter...
>
> Horned Grebes are also a mystery - I just saw my first Horned Grebe in
> wing-moult yesterday. Otherwise I have only seen basic-plumaged birds and
> no sign of wing moult. At Boundary Bay HOGR show up later that RNGR and
> WEGR. I spent the summer studying Horned and Red-necked Grebes in the
> Northwest Territories (a tough job, but somebody has to do it), and adult
> Horned Grebes leave the nesting ponds as early as June, with most gone by
> early August. Where do HOGR moult - on interior lakes or on the coast?
>
> My questions for my fellow birders then are:
>
> Do you know of any sites which host concentrations of grebes during August
> and September (note that many are quite distant from shore and you may only
> see a fraction of the birds present, depending on viewing conditions - so I
> am interested any any observations of, say, 30 or more birds for Red-necked
> and Horned Grebes and 100 or more birds for Western Grebes at a site at a
> time)?
>
> Does anyone see Horned Grebes in August/early September, AND does anyone
> see alternate or intermediate-plumaged Horned Grebes anywhere on the coast
> in late summer/fall?
>
> Do you know of any sites which host concentrations of grebes during winter
> and/or during spring migration - if so, when do the birds usually arrive?
>
> Thank you in advance for your help!!
>
> Bonnie Stout
> Simon Fraser University, Burnaby, BC
> bestout at sfu.ca
>