Subject: -Holly Trees (DEGRADE) bird habitat
Date: Feb 24 21:17:00 2004
From: Stewart Wechsler - ecostewart at quidnunc.net


In the dialogue of the advisability of killing a Holly shrub and not
mistaking it for a native Oregon Grape (Mahonia sp.) another tweeters
subscriber writes:

"Hummingbirds love Mahonias ... We have planted a Mahonia 'Charity' in our
yard recently, and will be ordering some 'Arthur Menzies' ..."

On buying named cultivars of Mahonia:

Yes, hummers like Mahonias, but if Tweeters subscribers want to contribute
to the preservation and restoration of the natural environment for the birds
and all other organisms I wouldn't buy just any Mahonia species or varietal
Mahonias. Not all Mahonias (considered a subgroup of the genus Berberis by
some) are our native Oregon Grapes. There are about 70 species worldwide.
Only 2 of them are native to western Washington. A third also occurs in
eastern WA. If the Mahonia varieties mentioned are actually the correct
species, i.e. M. nervosa or M. aquifolium, they are still aparantly
cultivars, which are normally less "natural" and are likely not to be from
local genetic sources. It is generally better to use local, wild gene stock
for locally appropriate native planting.

Nurseries that specialize in selling new and exotic species make trips to
other parts of the world with similar growing conditions to collect new
plant species and varieties to grow here. It is exactly this kind of moving
of organisms around the world that is responsible for a good deal of
degradation of natural environments and continuing extinctions around the
world. Many of you just read about two pacific Island birds that were just
declared extinct. Introductions of non-native species are the biggest
reason that a large percentage of island species of the world have gone
extinct. Some nurseries now claim to test these plants for potential
invasiveness, but there is no such test. While some species will have
greater potential for becoming the Starlings of the plant world, there is no
guarantee that something they bring over from a place like Korea, with
similar growing conditions won't spread here. If it does spread it almost
surely will replace native organisms. It could well be that one of the 67
species of Mahonia from another part of the world, that has never made it to
Washington, would survive better here than our native species. Our beloved
insects are less likely to be adapted to using them and our beloved birds
could have less food and our native Mahonais or other plants could be
out-competed and set on the path towards extinction along with the other
organisms adapted to co-exist with the declining or lost natives.

The native plant society has a website (wnps.org) that includes nurseries
that specialize in native plants. It is also sometimes possible to salvage
plants that are in a site scheduled for bulldozing or to grow them from wild
cuttings. If you want natives and have the patience to grow them from seed
you can easilly collect the seeds of many kinds from nature. A common
guideline for that is not to collect more than 5% of the seed from a given
area and not to collect seed of endangered species. Seeds of both native
Oregon Grape species - Mahonia nervosa and M. aquifolium are easy to find in
the wild. Just pick the ripe berries (nervosa start to ripen in August,
aquifolium start to ripen in late June, but uneaten berries may be found any
time of the year), eat them if you'd like (they're usually a bit sour - but
older berries are less so) and spit the seeds into a container.

Stewart Wechsler
West Seattle
mailto:ecostewart at quidnunc.net