Tweeters,

I want to echo Wayne's statements that this doesn't seem too unusual for siskins, but needs to be watched closely. The discussion brings up a really interesting question. How can we track population trends in nomadic or irruptive species whose population size can't be determined from their abundance in any one place? It's a difficult thing to do, especially with species whose ranges stretch across large, sparsely-inhabited areas.

It's quite possible that the number of siskins in North America hasn't changed from last year. The low numbers that we are seeing could just be short-term changes in distribution. The low continent-wide numbers on the CBCs could be due to the birds being in areas where there aren't many observers. It's also possible that the total number of siskins in North America has gone way down in the last few years. There could be concentrations of birds in certain areas this year, but they may not make up for the low numbers in Washington and other places.

I'm tempted to agree with the folks that say the siskins are somewhere else this year, and that they'll return as local food availability changes. This has happened for decades with siskins and other irruptive species.

But I'm also wary of making that assumption without a lot of data to support it. When Passenger Pigeons were declining precipitously, many people said, "The birds are still around, they're just somewhere else this year." It took a long time for most people to realize that wasn't the case - that the birds were actually gone. By that point, it was too late for the species to recover.

I'm not trying to be alarmist about the lack of siskins in our area this year, but we do need to be cautious about assuming the birds have just moved. I'm definitely going to be looking at the CBC data on them this winter. And I hope they come back to Washington soon!

Matt Dufort
Seattle, WA
zeledonia AT yahoo DOT com


----- Original Message ----
From: Wayne C. Weber <contopus at telus.net>
To: TWEETERS <tweeters at u.washington.edu>
Cc: GUY MONTY <ex_nihlo at hotmail.com>
Sent: Thursday, July 13, 2006 12:00:15 PM
Subject: Re: [Tweeters] RE: Pine Siskins


Tweeters,

As Guy states, numbers of siskins vary dramatically from year to year,
not just in the winter, but also in the breeding season. However, the
number of siskins present this year in southern BC, both east and
west of the Cascades, is lower than I can ever remember.

As an example, I have two BBS routes in the Nicola Valley
of southern BC (near Merritt) which I have surveyed most years since 1974.
Pine Siskins, on average, have been the 4th commonest bird on both
of these routes, with an average of 33 on the Brookmere route and
26 on the Canford route. This year, I tallied 4 siskins on the Brookmere
route (2nd lowest count ever), and none at all on the Canford route.
On the latter route, I also missed them in 2005-- the only two times
I have missed them in 16 years on that route.

Perhaps Guy is correct that they will "bounce back" in the near future--
I hope so. However, a quick look at Christmas Bird Count results
for last winter suggested that continental populations of Pine Siskins
were way below average. They were scarce to absent almost throughout
the western US and Canada, and numerous only in the Great Lakes
region.

If there is a disease problem with siskins, it is much more likely to be
salmonellosis rather than West Nile virus. There have been some
massive die-offs of siskins in the past due to salmonella outbreaks,
although I'm not aware of a major outbreak in the past year or so.

The numbers of siskins should be closely watched in the near future.
However, there is no question that disease outbreaks, as well as
food availability, can have a big effect on their numbers over
large areas.


Wayne C. Weber
Delta, BC
contopus at telus.net








----- Original Message -----
From: "Guy L. Monty" <guylmonty at hotmail.com>
To: <tweeters at u.washington.edu>
Sent: Thursday, July 13, 2006 11:24 AM
Subject: [Tweeters] RE: Pine Siskins


Hi siskin seekers,

The situation is much the same on Vancouver Island. Pine Siskins have
been virtually absent for almost a year now, after being pretty much ever
present and sometimes abundant, for at least 15 years. This isn't unusual
though, it's a natural function of finches moving around as their food
resources change.

I spent this spring in the NW corner of BC near the BC/Alaska border. Pine
Siskins, along with White-winged Crossbills and Common Redpolls, were
amazingly abundant there. The number of recently fledged young was
impressive as well. Last year in the same areas at the same time of year, we
had only a very few Pine Siskins, and no crossbills or redpolls.

In short, they will be back.

Guy L. Monty
Port McNeil, BC




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