Date: 12/19/17 9:29 pm
From: Jim Mountjoy <jmountjo...> [ILbirds] <ILbirds-noreply...>
Subject: IBET That goose in McLean County
On Sunday I received a phone call from a birder friend who asked "Are you
looking at a Barnacle Goose?". My reply was "Why would I be looking at an
escapee?". However, on Monday I was at a car dealership in East Peoria and
my business did not take TOO long, so I figured that Towanda was not so far
away...

I arrived at the borrow pit and had my scope on The Goose almost
immediately, thanks to some direction from Ted Hartzler. It is a pretty
bird. I also enjoyed the Snow Geese there (a county tick that I knew I
could actually count), but was disappointed by the lack of Cackling Geese,
although Ted's info on a couple of other spots to check eventually led me
to that species as well. Later I tracked down the State Farm White-winged
Scoter, so I definitely added a few county birds.

But about that goose. This is not my first Barnacle Goose, but the species
is not yet on any of my official lists. I would like to be relatively
confident that any bird I add to my list has a high probability of being a
wild bird. What does 'high probability' mean exactly? I am not sure. The
scientist in me says that it should be a 95% probability or greater, but I
suspect my standards could slip a bit below that level, from a listing
point of view. But would I be satisfied with 'a preponderance of the
evidence' (say, a 60-40 probability that this particular bird is wild)? I
don't think so. And the argument that 'you can't prove that the bird isn't
wild' does not seem right to me.

I know that Barnacle Geese are not rare in the ornamental waterfowl trade
(the prices are generally at or below $400 it seems, from a quick web
search). And Illinois, in particular, is a long way from Greenland or even
New England, where records are now routinely accepted. But I also know
that it is quite plausible that a wild Barnacle Goose could show up here,
so I do expect debate to ensue.

Today I opened my newly arrived copy of 'Ontario Birds' (Dec. 2017, Vol. 35
No. 3), and was surprised to see that the lead article was "The case for
accepting Ontario reports of Barnacle Goose" by Mike V.A. Burrell. It lays
out an argument for considering (many? some?) Ontario records of Barnacles
as valid wild birds. He presents what I feel are some strong points (I
didn't know that there have been seven Greenland banded Barnacle Geese
recovered in NE North America) as well as acknowledging some points that
might not support the 'wild' hypothesis so well. I would also add that
Illinois is not Ontario, and the arguments may not hold up as well in the
center of the continent. However, if you are pondering the provenance of
Barnacle Geese in North America, I think that you should try to read this
article if you can. (And yes, that certainly includes any IORC members who
may be reading ;) ).

Jim Mountjoy
Galesburg IL


D. James Mountjoy

Associate Professor

(on Sabbatical Spring and Fall Terms 2017)

Knox College

Department of Biology

2 East South Street

Galesburg, Illinois 61401-4999

309-341-7086
www.knox.edu

 
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