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Here's what Randy Milton found about ducklings and brackish water:
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From: Randy G Milton <miltongr@gov.ns.ca>
Date: Fri, 13 Jul 2007 12:57:57 -0300
To: Jim Wolford <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.
cheers
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> 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
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From: Fritz McEvoy <fritzmcevoy@hotmail.com>
Reply-To: naturens@chebucto.ns.ca
Date: Thu, 12 Jul 2007 16:09:45 -0300
To: naturens@chebucto.ns.ca
Subject: [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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