Birders,

In response to my message about the status of American Black Ducks in
the Pacific Northwest, Daniel Bastaja asked whether the introduced
population on Vancouver Island is "countable". The answer is yes-- if
you choose to follow the rule used for many years by the ABA (American
Birding Association) Checklist Committee. This rule stated, in brief,
that an introduced population is countable if "it has been breeding in
the wild for at least ten years, and is increasing in abundance or
maintaining a stable population without direct help from man".

Recently, the ABA Checklist Committee has adopted a more complex
definition of when an introduced population is "established", and
therefore "countable". Unfortunately, this definition is so complex
that it is hard to determine whether many small introduced populations
meet the criteria. However, the "ten-year rule" is still a reasonable
test for whether an introduced population is established and therefore
"countable", and is widely accepted among birders and field
ornithologists. The exception would be for long-lived species such as
parrots, in which a "stable" population could be maintained by
continued escapes from captivity, without any breeding taking place.

Of course, it should be stressed that no one should presume to tell a
birder what to count on his personal life list, state list, etc. The
ABA Checklist Committee and Listing Rules Committee rules apply only
to lists submitted to the ABA for publication. Nevertheless, their
recommendations are reasonable ones that many of us choose to follow
on our personal lists.

American Black Ducks in B.C. are certainly "countable" using the old
ABA rule, with a population of around 100 birds, and plenty of
evidence that they have been breeding in the wild since the late
1970s. However, they do not appear to be still increasing. Mute Swan
has a similar status on Vancouver Island, except that it has been
breeding since at least the late 1950s. On the other hand, Mandarin
Ducks have never become "established" in B.C., despite counts of up to
12 birds around Vancouver. I know of no positive evidence of breeding
in the wild, and numbers have decreased in the last 10 years.

As for Washington, although one could have taken the position that
American Black Ducks were established and "countable" 10 years ago, it
would be harder to take that position now that the population has
virtually died out. I doubt that the Everett area population was ever
as high as 100 birds. Only time will tell if the B.C. population of
Black Ducks follows the Everett-area population into oblivion.

By the way-- using ABA rules-- Burrowing Owls are not currently
countable in B.C., unless you can be certain that a particular bird
was hatched outside B.C. The B.C. population was extirpated in 1970 or
shortly afterward, and reintroduction efforts begun in the 1980s are
still continuing-- with massive "direct help from man".

Wayne C. Weber
Kamloops and Delta, BC
wayne_weber at bc.sympatico.ca



-----Original Message-----
From: Daniel Bastaja <birdingfaqs at hotmail.com>
To: bcintbird at egroups.com <bcintbird at egroups.com>;
bcvanbirds at egroups.com <bcvanbirds at egroups.com>
Cc: wayne_weber at bc.sympatico.ca <wayne_weber at bc.sympatico.ca>
Date: Saturday, October 28, 2000 10:03 PM
Subject: [bcvanbirds] Black Ducks in the Pacific Northwest


>Hi Wayne. This is Daniel Bastaja on Sat. Oct. 28th, 2000. Thank you
for your
>posting on the history and status of the Black Duck in the Pacific
>Northwest. It was very informative. I recall reports on the bird
alert line
>of the one that used to show up at the compensation lagoon at the
Tsawwassen
>Ferry terminal and I always wondered whether it could be included on
my BC
>list. Here's my question....You mentioned an established population
at
>Yellow Point on Vancouver Island. Are those birds "countable" as a BC
bird?
>I would think that if they are feral, have been there for many years,
and
>are breeding, they would be wouldn't they? Sort of like the Crested
Mynahs
>in Vancouver? Anyway....just wondering. I never did see the one at
>Tsawwassen so that's a species I don't have for BC yet.
>
>Regards,
>Daniel Bastaja
>e-mail: birdingfaqs at hotmail.com
>_____________________________________________________________________
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