Tweeters:

Seems we have a vigorous discussion on how differing plant ecosystems impact
our birds and other wildlife underway, just couldn't resist the chance to
chime in. I think the observer who stated that Douglas' Hawthorn and the
other native shrubs are better overall for insectivores than non-native
Himalayan Blackberry (Rubus discolor) and Evergreen (R. laciniatus) is
correct. Those deciduous shrubs do seem to attract more insectivores; Red
Elderberry (Sambucus arborescens) and sapling Red Alders (Alnus rubra) do as
well.

Still, some of the natives strike me from a practical standpoint as being
far harder to establish quickly and in quantity than the non-native
blackberries, especially in suburban habitats, whereas the non-native
blackberries usually just show up themselves on disturbed ground. Yet we
seem to all agree that as far as habitat, the Himalayan Blackberry patch is
a lot more uniform than a native shrub community covering the same ground.
We have an expanding patch ourselves in n. Lake Stevens at the edge of the
lawn, it's remarkable how fast that species overruns natives; speaking of
how monotone the resulting stand is, ever look at the ground below a dense
thicket? Nothing or almost nothing there under the closed canopy...I've
been watching with the machete at the ready as the thorny canes now are
sprawling onto a Pacific Madrona (Arbutus menziesii) that took years to
prosper.

So it's easy to see the downside of the Himalayan and some of the other
non-native Rubus, but I think various observers have made good counterpoints
about how certain avifauna has adapted. Beyond the mention of species that
consume the berries, ever think about winter Zono flocks, say, in Snohomish
and Skagit counties? I'd venture to say that before land-clearing for
agriculture up there, leaving brambly thickets at the roadside edges and
margins, Zono numbers were probably vastly less when only native thickets
bordered forest along rivers, shorelines, etc. And what of the raptors, and
especially accipiters that pick off Zonos? At Graysmarsh near Sequim, same
deal--species like Spotted Towhee, Zonos, Song, Fox and Lincoln's Sparrows,
and Bewick's Wren, non-native blackberry thickets are the place to look.
Other than providing cover, one gets the impression that the monotone
thickets provide a sort of artifical warming effect, providing milder
internal conditions and more wind protection in winter than native shrub
thickets, which often tend to be more open. Those elusive wintering
Orange-crowns some to mind here, they also often seem to show in low
Himalayan thickets. Yet all these species noted above will show in the
native shrub-hedgerow as well, although not always as abundantly.

Scott Atkinson
Lake Stevens
mail to: scottratkinson at hotmail.com