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Hi Jim & All, July 14, 2007
I don't know what the official definition of brackish is, but 15 ppt
would be an extreme condition I think; near or at the upper end.
For example, some brackish samples, based on plants present, that I
took in the 1950s had median total solids of ~1 ppt and maximum of 12.3 ppt.
Yt, DW
Jim Wolford wrote:
>Here's what Randy Milton found about ducklings and brackish water:
>----------
>From: Randy G Milton <miltongr@gov.ns.ca> <mailto:miltongr@gov.ns.ca>
>Date: Fri, 13 Jul 2007 12:57:57 -0300
>To: Jim Wolford <jimwolford@eastlink.ca> <mailto:jimwolford@eastlink.ca>
>Subject: Re: FW: [NatureNS] salt water black ducks
>
>Hello Jim:
>
>I could not quickly find much information on this question but a paper by
>Barnes and Nudds (Auk 108: 898-98. 1991) reported that black duck ducklings
>had higher survival and growth rates than did mallard ducklings with salt
>concentrations increasing up to 15 ppt. Although survival increased with
>duckling age, salinities greater than 15 ppt resulted in the death of both
>species if less than 7 days old. At 21 days, there was no difference in
>duckling survival between the species up to 15 ppt.
>
>cheer
>s
>
>Randy Milton
>Manager - Wetlands and Coastal Habitats Program
>Department of Natural Resources
>136 Exhibition Street
>Kentville, Nova Scotia
>B4N 4E5, Canada
>
>>>>Jim Wolford <jimwolford@eastlink.ca> <mailto:jimwolford@eastlink.ca> 7/12/2007 6:02 PM >>>
>>>>
>I once heard on the soundtrack of a Ducks Unlimited film on the Bay of Fundy
>that black ducks are different from other surface-feeding ducks (vs. diving
>or bay ducks) in that their ducklings are able to tolerate salt or brackish
>water, whereas other dabblers' ducklings can only handle fresh water when
>they are young. Thus black ducks may have had a long history of breeding
>along brackish shores and in salt-marshes.
>
>Perhaps Randy Milton of N.S. Dept. Nat. Resources can comment on this?
>
>Cheers from Jim in Wolfville
>----------
>From: Fritz McEvoy <fritzmcevoy@hotmail.com> <mailto:fritzmcevoy@hotmail.com>
>Reply-To: naturens@chebucto.ns.ca <mailto:naturens@chebucto.ns.ca>
>Date: Thu, 12 Jul 2007 16:09:45 -0300
>To: naturens@chebucto.ns.ca <mailto:naturens@chebucto.ns.ca>
>S
>ubject: [NatureNS] salt water black ducks
>
>Hi All,
> While chatting to a chap in Ingonish today he mentioned that he had some
>Black Ducks that had raised their broods along the shore of North Bay in
>Ingonish. I was somewhat disbelieving but he told me where to look and I was
>able to video a family group feeding on snails?algae?seaweed? I'm not sure
>what among rocks along the shore.
> He said this behavior had begun when small ponds near the shore had
>frozen over in late fall and the ducks instead of migrating had adapted to
>coastal shoreline feeding.This spring they then fledged their young in the
>new feeding location. This has happened in at least two locations on North
>Bay.
> The location did have a strong sulfur smell that may indicate a sewage
>outfall which has attracted the ducks.
> Has this behavior occurred in other parts of the province and why would
>it occur? All the best.
> Fritz McEvoy
>
> Sunrise Valley CB (near Dingwall)
>
>
>
>
>Windows Live Hotmail, with safety bar colour coding, helps identify
>suspicious mail before it takes your daughter out on a date. Upgrade today
>for a better look. <http://g.msn.com/8HMBENCA/2752??PS=47575>
>
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