The only thing that comes to mind is a small Crabapple, Pink Princess, perhaps. The birds will eat the fruits.

The list of shrubs that have been trained into a sigle stem tree is impressive, but none fit so well with your tall order. A King Edward flowereng currant would be a hummingbird magnet, good fall color, peeling bark, and leaves that would be too small for what you want.

Crabapple gets my vote.

Cornus kousa
Maple (many to choose from)
Sourwood (may eventually become too large, but will take a long time doing so.
Aesculus Parviflora (Horse Chestnut)

how about a Cotinus (smoke bush) I have one that is suppose to get about 10-15' tall.

There are smaller Crabapples, those with small apples that persist are magnets for birds and they look cool in winter.

Paperbark Maple is a gorgeous small tree.

Japanese Snowbell is too.

Styrax obassia, awesome tree with large leaves, it blooms and then has interesting seed pods. Very cool tree!
Stewartia pseudocamillia, another amazing tree with something interesting going on all year! Leaves on the smaller side. Great fall color.

Your width restriction is a very limiting factor - nearly all small trees will develop a rather spreading habit over time and 12' is definitely on the low side. If you can tolerate a greater spread at maturity (nothing to worry about immediately), then either Cornus kousa or C. mas or most flowering crabs will work, although none of these are what I'd consider major shade providing trees. And if you consider the leaves on an Amelanchier too small, then these may be as well. Arbutus unedo is also an exceptional small tree for year round appeal and wildlife attraction.

Other than that, many of the previous suggestions have ommitted consideration of your condition #6, which you state is very important. Very little appeal to wildlife from maples, styrax, stewartias, cotinus, etc. And most nut producing trees for this area are going to get far larger that you wish or be rather weedy, suckering shrubs rather than small trees.

Being a genus with three native species, maples attract songbirds whereas I'm not sure what the big wildlife draw would be for Arbutus unedo. Presumably also being a native genus there would be a connection but I can't say I've ever seeing much going on in a strawberry tree here. I have seen the uneaten fruits all over the ground.

Here is a link that might be useful: Article - Trees that merit planting in Seattle by Arthur Lee Jacobson

Check out...

Chitalpa

Search the web for images.

There are some nice Catalpa trees in the Portland metro area as well as Milwaukie. they are pretty, but you do have to re shape them every few years or the limbs sort of self prune from the weight of the leaves. They are really nice old trees and you can shape them to some extent. Be prepared to have to prune extensively every other year or so. The "Hazelnut" or Filbert, to this 3rd generation Oregonian has some draw backs as well. It is not a tree that makes a long standard trunk, then branches out, rather the crotch of the tree is naturally about 3 ft off the grond frequently. You may find some that are more to a taller standard, but they tend to limb out wide and low. this makes them good for a kids fort, or an orchard, but not tall and narrow, unless you can train up a "sucker" which will shoot up tall and straight off the base of the trunk. These are usually not seen as desirable, and removed, how ever, if one does "get away from you" they tend to be taller than the parent tree. these trees must be trimed, suckers cut, sprayed for bugs, unless you never intend to eat the nuts, but leave them all for the birds, and I am not sure if you can find anything in an organic for this. It is a beautifull tree, but I doubt its what you want. Elderberry trees that are nice, but so far the crab apple seems like it might be your best bet. you can get a dwarf, and that will help some.

You must be talking about pollarded catalpas.

Most arbutus species are commonly included on lists of wildlife-friendly plants. Flowers of arbutus are quite pollen-rich and attract honey bees. Butterflies and hummingbirds are attracted to the flowers because of nectar content and the fruit is eaten by a number of small mammals and native songbirds.

If #6 is 'really important' one tree or even many trees of one species, no matter how fabulous, isn't going to make much of an impact. If you haven't already, you might consider using wildlife friendly concepts in most of your landscape.
Cheers

Here is a link that might be useful: creating wildlife habitat

Wildlife value can be very region and species specific. During a study described in an article published in the UW Arboretum 'Bulletin' it was found that native songbirds tended to focus on native tree species, even when the foreign ones planted on the same site (the Seattle arboretum) were in the same genus.

Another variation is that foreign origin (exotic) trees and shrubs that are magnets for birds (foreign and native) when in fruit can have become pest species here partly as a result of birds spreading them around. Examples are English holly, ivy, cotoneasters and European mountain ash.

I'm with the person who suggested an Arbutus species- my first thought was a Pacific Madrone (some people in Washington refer to them as Madrona), as they've evergreen, have nice berries for birds, have an attractive red bark, and once established, don't need any water in the summer.

That said, it will take some pruning to stay in your size restrictions, but it does tolerate pruning quite well.

Here's some links to give you an idea of what I'm talking about:
http://www.laspilitas.com/plants/35.htm
http://www.rainyside.com/features/plant_gallery/nativeplants/Arbutus_menziesii.html
http://www.fs.fed.us/database/feis/plants/tree/arbmen/index.html
http://plants.usda.gov/java/profile?symbol=ARME

Lots of pictures included in the links.

In case anyone responded to my post, I did not say Catalpa.

The "Chitalpa" is still what I meant.

See link below.

Here is a link that might be useful:

That photo is beautifull, Id LOVE to have one like that in my Garden!

Once it got picked up by one or two large wholesale container nurseries many of the garden centers here had x Chitalpa tashkentensis but it seemed they were often being sent tall poorly branched sticks that also often developed a foliage mildew under the less-than-perfect watering regimes of local outlets. Probably these two points resulted in their rapid disappearance as a common item. There are some good specimens growing in local gardens (see TREES OF SEATTLE - SECOND EDITION) and phone calls would probably produce a source somewhere nearby. If not, can be ordered through the mail.

I first saw a Chitalpa in Beaverton. It was an awesome small street tree. But I had no idea what it was. College didn't cover it in ID class, nor had I come across any while pruning for 10 years.

The form, size, and especially the flowers, caught my attention. A worker at Teufel Nursery - who came from California - told me what it was.

I can't say that the flowers are like foxglove, but they remind me of foxglove.