Hello, all. I'm a student at UW, Seattle doing a project on a new
non-native animal to the Seattle area... the nutria (Myocastor Coypus).

I had some thoughts on invasives that reflect my recent observations of
nutria and other wildlife in Union Bay Natural area, Seattle. The plant
species composition in the bay is an interesting hodge-podge of native and
non-native species. Within the past few years, nutria started showing up in
the bay. I will share about this in a little bit, but first...

I have had the pleasure of spending many hours in the area observing the
wildlife, and have seen some surprising species show up in relation to some
well established non-natives. For instance, I have seen western sandpipers
show up in the bay in small flocks and wander across the dense summer mats
of Fragrant water lily (Nymphaea odorata) which is a non-native species to
the region. The presence of the invasive water lilies creates micro-habitat
for tiny animals such as unimaginable numbers of springtails and other tiny
insects. This attracts the western sandpipers during late summer. Without
the water lilies, there wouldn't be an microhabitat to attract these little
shorebirds to Union Bay.

Now, I am not saying we should encourage the introduction of non-native
species. I believe strongly that we should remain vigilant and active in
the management of non-native species; however, it seems wise to me to also
be open and aware to what is actually occurring in the habitat in question
and not just let out fears influence our management plans. This is not an
attack on anyone nor am I finger point in anyway, so please don't
misconstrue my words. But, I have noticed that management plans for
non-native species are often more political rather than based in real
observations and scientific data.

In areas where invasive species have been established for a long time, such
as in Union Bay with the fragrant water lilies it seems a good idea to do
some serious scientific investigation and observe what kind of interactions
are occurring in that area between native and non-native species of both
plants and animals. Instead of just jumping in and removing them because
they are invasive.

Union Bay Natural Area happens to be a intensely managed area, with strong
programs to control the invasive spread of Scotch Broom, Himalayan
Blackberry and other non-native species. The recent Arrival of nutria into
the system has raised a lot of questions. Currently, the nutria shares this
habitat with several families of beavers and many muskrats. Also, they seem
to be eating many non-native as well as some native plants in the ecosystem.
We are still investigating what species they prefer to eat at this time of
year as well as learning the locations of active dens, and trying to get a
general sense of how many nutria live in the area ( a rough idea, not an
exact population #). Actually, for those of you interested in contributing
observations from the Union Bay area or that are curious about the project,
please visit our webpage at:

students.washington.edu/ptv/

Another interesting bird-related observation I have made in Union Bay was
the large shift in number of breeding pairs of savannah sparrows in the
prairie habitat. Several years ago, large areas of the natural area were
covered in dense grasses made up mainly of native Puget-Sound prairie
species, some up to almost 6 feet tall. Many breeding pairs (perhaps up to
50) savannah sparrows nested in this well established habitat. However, due
to a management effort to control the invasive Himalayan Blackberry this
area was mowed repeatedly and the blackberry where pulled manual as well.
The mowing completely altered the habitat for the savannah sparrows and they
have not returned in such numbers for several years. Now, in the year of
2006 it appears once again the grasses are establishing themselves (though
not yet to the same extent) and the savannah sparrows are showing up in
large numbers.

So, was it and does it continue to be a good idea to removed the invasive
blackberry in this area?
What impact do we have on other species when we remove the blackberry?

These are basic questions, but are also much more involved that they seem at
first glance. There is no management plan perfect enough to include the
needs of all species. So the question becomes, what are we managing for???

Food for thought,

Filip T.

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