On Sun, 6 Jan 2002, Jamie Acker wrote:

> As for their interaction with Barred Owls, I have not personnally
> witnessed one. I would think that they being significantly smaller and
> more prone to hugging tree trunks than WSOW that they would fare better.
> I do have indirect evidence that suggests that Barred Owls do impact
> their population, or at least their response. When NSWO first become
> responsive to calls in October, they can be found fairly easily in
> suitable habitat. By December, I frequently no longer get responses from
> NSWO if the habitat is also BDOW habitat. I also think that NSWO are
> more nomadic and that may be a reason for fewer responses.

I've been whistling a Saw-whet call and had a barred owl come down the
path at me with obvious evil intentions. This was at a site where I'd had
a Saw-whet answer a week earlier, but I never heard one at that spot
again. I also got buzzed by a large owl (unidentified) when whistling
like a saw-whet in a pasture one winter in Ontario (at night).

However, at the same time, though much of the range of both owls they
share habitat, and NSWOs are not shy about calling. I doubt the influx of
Barred Owls into the Pacific Northwest would be responsible for a regional
decline in NSWOs. More likely it's just normal fluctuations in the local
wintering population of this *extremely* erratic owl. Remember, one pair
of Saw-whets can raise more than a half dozen young in a good year, so the
population might, what, triple if conditions were right across a broad
area? And Saw-whets both migrate and move around during the winter (shown
by banding recoveries in the midwest), so it's easy for local numbers to
fluctuate. Here are total saw-whets counted for a Christmas count in
Massachusetts (Quabbin Reservoir count) in each of the last 12 years:

1990 this year
2 15 42 13 38 61 5 7 15 11 12 na 9

Bounces all over the place. Are the owls declining since their mid
nineties peak? If so, they did it awful fast, and there have been Barred
Owls there all along.

One explanation for owls being more widespread in October than later is
that October is probably the migration peak (it is in the east at
comparable latitudes to WA).

It's logically possible that Barred Owls are affecting NSWO numbers, but
it seems to me like a real stretch to even suggest a regional decline.

Chris Hill
Far Away
chill at coastal.edu