Geography Reference
In-Depth Information
Laura Farwell cranked up the volume as the previously recorded Pacii c wren
call boomed from a speaker she concealed in the nearby bushes. Like a heat-
seeking missile, a perturbed Bewick's wren streaked in looking for a i ght.
That's right, a
Bewick's
wren responded to Laura's “playback experiment”
although she intended to coax a territorial response from the resident Pacii c
wren. Laura was learning how hard it is to be a Pacii c wren—the icon of un-
settled northwestern forests—when your forest becomes a suburb. Urbaniza-
tion not only reduces and isolates what forest remains, but also invites a new
bully onto the block, the streetwise Bewick's wren.
Bewick's wrens thrive in the shaggier parts of cities and towns across the
United States. I always enjoy watching them l ag their long, cocked tails as they
bounce among the undergrowth. They are big for northern wrens—a quarter
again the size of a tiny Pacii c wren. Their song,
t-t- riiing- aling- ling- ling,
zips
through the gray gloom of an urban spring day. Out west, Bewick's wrens are
classic adapters, taking to new suburbs as soon as the trees begin to fall. They
are never particularly abundant, but what they lack in numbers, they make up
in chutzpah. Not only are they aggressive in the face of a challenge—both from
within their own and from closely related species—as Laura discovered, but
they are also known to puncture the eggs of a rival. Their occurrence in newly
created subdivisions puts them in unusually close contact with their forest-
dwelling brethren, and this proximity is a second punch from urbanization to
the gut of the Pacii c wren.
When we watch wildlife respond to urbanization, in both positive and
negative ways, we tend to focus on the fortunes and failures of a single species.
But as the birds of a forest adjust to human settlement, the entire community is
reshul ed. The changing abundance of one species may ripple through the
full web of life. The web is refashioned, as new strings are added and old ones
are diminished or reconnected into a new architecture. For example, research-
ers from Perth, Australia, noted that some of the decline in species diversity at
Kings Park may have been due to the predatory prowess of a particular adapter,
