Geography Reference
In-Depth Information
sions were constructed and inhabited by suburban people. Three species, the
northern spotted owl, the yellow-billed cuckoo, and the marbled murrelet,
which are hypersensitive to forest loss, had disappeared from our inhabited,
lowland forests decades earlier. They were also the only extinctions recorded
just north of the border in Vancouver, British Columbia. Ten of the forty-four
species that we found before development were avoiders, and each declined as
construction ensued. In contrast, the abundance of these species was stable in
nearby forested reserves over the same period of time, and they were much
more abundant in these forests than they were in the established neighbor-
hoods we also surveyed. The recent and ongoing avoidance of development
by the ten extant species we studied suggests that others may soon follow the
owl, cuckoo, and murrelet. Certainly avoidance of built areas is an important
reason why many of them are declining throughout western North America at
rates of up to 2.5 percent per year.
We can rank our ten avoiders according to their sensitivity to development
by considering the frequency with which they were locally eliminated. Atop that
list is the Townsend's warbler, a stunning black-and-white denizen of the upper
coniferous canopy who sports a face striped with black and yellow. While gener-
ally rare at our lower elevations, the wispy songs of this warbler were silenced in
all forests we observed being converted to neighborhoods. Its close relative and
resident of lowland maple forests, the black-throated gray warbler, also disap-
peared from two-thirds of the neighborhoods. Pacii c wrens, mouselike birds
that scurry among the ferns and perch on hundred-year-old stumps to pour
forth sweet concertos, were uprooted from four developments and reduced from
local prominence to a measly pair or two at three other sites. The remaining
avoiders were all lost from at least one site, but hung on during the tumultuous
period of forest conversion at a majority of the neighborhoods we studied.
The avoiders were migratory and year-round residents. Six of them—
Pacii c-slope l ycatcher, Swainson's thrush, western tanager, and Townsend's,
Wilson's, and black-throated gray warblers—were neotropical migrants.
