Dennis et al.,

I've been following the flycatcher thread with interest because in my
central Wallingford yard, surrounded by your average Seattle garden
mosaic of lawns, driveways, landscaped flowerbeds and the occasional
tree, I seem to have a pair of olive-sided flycatchers. I've got about
15 trees growing in my little backyard, including a mature black locust
and a crowd of 10-20-foot high saplings I planted when I moved in five
years ago. One branch of the locust is dead and two of the saplings
have lots of bare branches -- I've left these as habitat. I also have a
5-year-old largely native understory of herbs and shrubs that is doing
quite nicely, a couple of watering holes and a few feeders. So on the
face of things, I have a pretty decent bird yard developing. However,
there's no getting around the fact that it's a tiny island in a sea of
even more marginal habitat. So why do I have a pair of olive-sided
flycatchers?

My guess is that reduced habitat is forcing the late-comers, the young
and inexperienced, the very lost, or the least fit birds to seek out
whatever patch of ground they can find, sort of like the the bedraggled
spotted owl that roosted in Everett for awhile a few years ago. Just
because they're here doesn't mean it's good habitat. It may just be the
best they can find at the moment. I do love my pair of flycatchers, and
they do seem to be finding plenty of insects -- I lean back in a chair
on my back deck and look up at them flycatching off the dead branches
each evening. But I wonder about them.

I've had a bunch of new yard birds this year, which may be testament to
the growing maturity of my garden (western wood-peewee, cedar waxwing,
orange-crowned warbler), but they've all blown through pretty quickly.
I'm curious what others have to say about my olive-sided flycatchers,
who have been courting and demanding beers quickly for three weeks now.

Katie

-----Original Message-----

Message: 28
Date: Tue, 17 Jun 2008 10:24:07 -0700
From: Dennis Paulson <dennispaulson at comcast.net>
Subject: Re: [Tweeters] very late migrant?
To: tweeters at u.washington.edu
Message-ID: <42FF568C-3710-450E-8920-9FF6DE1081FD at comcast.net>
Content-Type: text/plain; charset="us-ascii"

Dianne and Amy et al,

I think Pacific-slope Flycatchers are one of many species that breed
in forested environments all around Seattle but probably don't breed
in the city any more, except perhaps in our most spacious parks. We
badly need continued censuses of birds in the city parks, just to see
if I'm right. I'm certainly right about my yard and the well-wooded
Thornton Creek ravine behind it, where I have never before detected a
PSFL in the summer in 17 years of living here.

The city is losing birds, particularly migrant birds, especially
those that migrate to the tropics. These are birds that have to
arrive in migration and set up territories anew every spring. It is
fairly well known that cities can be POPULATION SINKS, places where
populations would decline, because mortality exceeds natality
(production of young), if it weren't for continuing immigration from
the surrounding natural habitats (which are POPULATION SOURCES). As
we develop and expand the suburbs around the city more and more, we
are essentially pushing the population sources farther and farther
away, to the point at which certain species disappear completely from
the city, even though there are appropriate habitats here and there.
This really seems to affect migrants more than residents, which can
make do with reduced habitat quality. One reason they do, I suppose,
is because so many of the resident species are aided and abetted by
bird feeders. Not so with Pacific-slope Flycatchers.

In some species, individual male birds continue to come into what
seem like acceptable habitats in the city, sing their little hearts
out, but fail to attract a female. Perhaps the females are better at
assessing the value of habitats. If I were a female, I would
certainly try to find the very best breeding habitat when I arrived
from a winter in Mexico, and it wouldn't be a 10-acre patch of
woodland in a city park surrounded by development.

We also need a lot more research on, for example, the density of
insects available to an insect-eating bird in a wooded city park as
opposed to a similar forest outside the city. I suspect there will be
a substantial difference. Having wooded parks and green belts in a
city is a great idea, and a wonderful amenity for both humans and
some subset of wildlife, but we are kidding ourselves if we think
these habitats will support the same biodiversity as the expanse of
natural forest that used to be here.

Dennis