Dennis,

Your comments touch on two interests of mine-- urban birds and
bird food habits-- which date back to my M.Sc. thesis on birds
of residential areas in Vancouver, BC.

If you are trying to make the point that people in cities in the
Northwest don't grow many native plant species in their yards,
you are quite correct. In large cities like Seattle and Vancouver,
for the most part, we destroyed most of the native vegetation long ago,
and then began replanting with mostly exotic species. I would expect
that at least 90% of plant species stocked by most nurseries are
exotic, and they will not stock many native species until their customers
start demanding it (if then).

However, this pattern of mostly-exotic species in people's yards does
not hold everywhere. In suburbs and smaller towns, where lot sizes
are often larger, there are often sizable chunks of native vegetation left
in people's yards. For example, most of the madrones I have seen
around Victoria are in people's yards, not "out in the country".
True, most of the areas with lots of madrones are in suburbs such
as Saanich, Metchosin, and North Saanich, rather than in Victoria
itself. Zoning regulations which require a large minimum lot size will
generally result in much more native vegetation being retained, and
I suspect that these large minimum lot sizes are the rule in many
smaller municipalities and "semi-urban" areas around Georgia Strait
and Puget Sound.

At any rate, the important role of madrones in the winter ecology
of American Robins (and several other species, including Varied
Thrushes and Band-tailed Pigeons) cannot be ignored.
I would disagree with you that madrones are local in distribution.
Although they are commonest in areas with less than 40 inches
annual precipitation, and on thin soils, they occupy large areas
on southeastern Vancouver Island, around Puget Sound, in western
Oregon, and in northern California. They are one of the most
important food sources in the region for frugivorous birds, and tend to
retain their berries much longer into the winter than most other
trees and shrubs.

Among exotic species, hollies are certainly important, as you note.
There are several commercial holly farms near Victoria, which help
to sustain the high wintering numbers of Robins in that area.

Bohemian Waxwings are another kettle of fish entirely. In most areas
(e.g. the Okanagan Valley of BC, where I grew up) they seem to
subsist in winter on a diet of 90% or more non-native species.
The main food sources there seem to be mountain-ash berries
(probably one suburban yard out of 3 or 4 has a mountain-ash tree)
and unharvested apples, which of course are abundant in this
apple-growing area. In fact, the ONLY native species that I have seen
Bohemians using extensively is wild rose. (It's impressive to see
a flock of 1000 or more Bohemians "swarming" a patch of wild rose.)
There is so much cultivated fruit available in the winter in the
intermountain areas of the Northwest, and in the Great Plains, that
I suspect it has caused a permanent, and significant, increase in
the world population of Bohemian Waxwings, by removing winter
food supply as a key limiting factor for the species. The same cannot be
said for American Robins, although cultivated fruits may have
resulted in an increase in numbers wintering in some areas.


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



----- Original Message -----
From: "Dennis Paulson" <dennispaulson at comcast.net>
To: "Tweeters" <tweeters at u.washington.edu>
Sent: Monday, December 04, 2006 6:41 PM
Subject: [Tweeters] follow-up on berry interesting


I think I wasn't clear enough in my message, as some people have
responded by telling me which native plants are used by birds,
something I knew. What I really wanted to know was how many yards
have native plants that fruit-eating birds are visiting. Seems to me
that the vast majority of plants that robins use right in the city
are non-native, same true with waxwings in eastern Washington. I
assume the native plants that have bird-dispersed fruits are
presumably much used out in the country, but you sure don't see many
of them in people's yards. The note from Ruth Sullivan confirmed
this. She wrote about all the native plants she had planted, very
commendable, then mentioned the robins feeding on her pyracantha and
cotoneaster! Perhaps the non-natives, especially if they are
cultivars that have been bred for it, produce more fruits than the
natives, perhaps also later in winter, and are more important in
supporting flocks of robins and other fruit-eaters here in winter in
urban/suburban areas. It may be that the native shrubs and trees that
grow scattered through the woods are important, but we just don't see
concentrations of birds at them because the plants aren't that abundant.

Madrones are a good example of an important native species, and they
grow in large enough stands that sometimes there are great numbers of
frugivores in them, but they are local in distribution (and, I
believe, declining in some areas), and those stands aren't usually in
people's yards. Ed Swan's mention of 15-20 species in madrones
boggles my mind a bit, though, and I wonder if you would provide a
list, Ed. I've seen Steller's Jays, Band-tailed Pigeons, Cedar
Waxwings, Varied Thrushes, and robins, and I'm curious about the
species list beyond that.

I didn't mention hollies, which are probably as important as madrones
in attracting huge flocks of robins. Hollies are planted in big
stands in some areas, and I've seen hundreds and hundreds of robins
in them, as well as other fruit-eating species. I've always thought
that if you wanted to spend time looking for Dusky and Eyebrowed
Thrushes and the like, you should hang out in holly groves. Probably
madrone groves also.

Thanks, everyone, for all the great response!

Dennis
-----
Dennis Paulson
1724 NE 98 St.
Seattle, WA 98115
206-528-1382
dennispaulson at comcast.net