Birders,

I enjoyed Mike Patterson's commentary on introduced populations, and I
tend to agree with most of what he says-- especially the "don't even
get me started on Turkeys"! I've seen introduced Turkeys in southern
B.C., a couple of places in Washington, and near Elgin, Oregon. It
seems that some of these populations are much more dependent on man--
at least in winter-- than American Black Ducks ever were. Counting
Turkeys seen in a farmer's barnyard (even sitting on top of a hay
wagon, in the case of some of the birds near Elgin) feels a bit like
counting chickens on your life list. However, to give Turkeys some
credit, the main introduced population in B.C., in the Creston and
Cranbrook area, didn't even originate from birds released in B.C. It
originated from birds introduced in NE Washington, which spread across
the International Border under their own power.

Deciding whether an introduced population is "established", whether
it's a question of counting it on one's list or of deciding whether to
include it in a state or provincial bird book, is no easy task. Case
in point: Crested Myna. Mynas were first reported on the loose in
Vancouver in 1897, and they are still there now. However, a population
estimated at about 20,000 birds in the 1920s is now down to probably
fewer than 20 birds, and I expect they will be gone within 5 years. As
recently as 1970, I estimated the Vancouver area population at about
5,000. However, a catastrophic decline began about 1980, and the end
seems inevitable.

When the last Vancouver myna cashes in its chips, will the ABA declare
that they never existed, and that no one can count them on their ABA
area list? Baloney! They have survived in Vancouver for more than a
century, and were a significant part of Vancouver's birdlife for much
of that time. Of all the ultimately unsuccessful bird introductions in
North America, this is the one that came closest to succeeding. It is
ironic that the demise of mynas appears to be mainly a result of
nest-site competition with another introduced species, the European
Starling.

Whether one "counts" introduced birds on one's list or not, Mike's
point is well taken-- we should keep track of the numbers and
distribution of escaped/introduced species, just in case they do get
firmly established and become a huge problem like Starlings. One can
never assume that a population even in the tens of thousands is here
to stay. By the same token, we should not assume that a species whose
numbers have been bouncing along at a low level may not "break out"
next year and begin to spread like wildfire. The Mandarin Ducks around
Vancouver may not yet be kaput!

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


-----Original Message-----
From: Mike Patterson <celata at pacifier.com>
To: Multiple recipients of list OBOL <OBOL at BOBO.NWS.ORST.EDU>;
tweeters <tweeters at u.washington.edu>
Date: Wednesday, November 01, 2000 1:09 PM
Subject: A slippery slope - the ten year rule


>A slippery slope - the ten year rule
>
>Yeah, I have a life-list, and a state list and a year list and a
>yard list. I even once extrapolated for the year I'd likely hit
>400 in Oregon based on average new state birds seen per year
>(how's that for being a data wonk?). But having said all that, I
>don't take the 10 year rule very seriously and tend to exclude all
>"exotics" except unequivocally established species like starlings,
>House Sparrows and Rock Doves.
>
>I've seen Eurasian Tree Sparrow in Astoria... on the ABA list
>having passed the 10 year test in St.Louis, MO. I've seen Mute
>Swan and Black Swan, Monk Parakeets and Budgerigars in Clatsop Co.
>Mute Swan has even passed the 10 year test in Oregon in very
>localized circumstances, though it's not countable on the Oregon
>list. Monk Parakeets have been nesting near the Portland Airport
>for at least 20 years, but are not countable.
>
>Then there are the California Quail here in Clatsop Co that would
>almost certainly not pass the 10 year muster. Ring-necked
>Pheasant in Clatsop Co, without continuous reintroduction, is
>also precarious... and don't even get me started on Turkeys.
>
>Many of these "stable" introduced populations are so localized and
>so difficult to genuinely prove non-assisted that counting them as
>wild seems like cheating. And many allegedly wild populations
>(Ring-necked Pheasant being a case in point) probably would not
>remain in some areas if not for introduced food sources like grain
>stubble (or bird seed in backyards or french fries in parking
>lots). Once an exotic becomes countable we tend to lose our
>interest in whether it really deserves to be counted, but claiming
>a countable feral population in Bend does not make birds on
>Trestle Bay any less suspect or any more countable there.
>
>On the other hand, the 20,000 European Starlings that roost under
>the Columbia River Bridge got to the lower Columbia by the sheer
>force of their own biology. They were not introduced to Clatsop
>County. They've earned the right to be ticked
>
>Durrell Kapan and I once did a thought experiment. How many
>Wrentits would one have to capture from Fort Stevens and drive
>across the bridge to Fort Columbia to make a viable population?
>Once released, how many years would it take for them to reach the
>British Columbia border? What environmental impact would such a
>release have? How many birders would wait 10 years before they
>put them on their Washington list?
>
>Dubious exotics (including American Black Duck) should be
>counted, but in my opinion, they should not be countable.
>
>But as Wayne said, it's your list.
>
>--
>Mike Patterson Alas, to wear the mantle of Galileo,
>Astoria, OR it is not enough to be persecuted
>celata at pacifier.com by an unkind establishment,
> you must also be right.
> ---Robert Park
>http://www.pacifier.com/~mpatters/bird/bird.html