Geography Reference
In-Depth Information
resighted stayed within the square kilometer area (not quite half a square mile)
where we i rst encountered them before construction. In i ve cases where we
could precisely map their territories, we found that wrens moved an average in
excess of the length of two football i elds (720 feet) between years. To us that
isn't far, but to a two-inch wren it's a haul. We saw short movements in direct
response to partial clearing—the removal of a few cedar trees caused one wren
to shift about a football i eld away. And we saw long moves in response to large
clearings—an established male wren moved eight times as far to i nd a secluded
forest when the earthmovers leveled the land abutting his territory. So my dad
was at least partially correct. Some animals do move and i nd new homes in the
pieces of paradise that remain around our developments.
We never saw the wrens that owned territories in forest reserves or estab-
lished neighborhoods move like those in construction zones. In both places,
Pacii c wrens are real homebodies. Our precise comparisons of sixteen mapped
territories suggested that forest and neighborhood wrens move only half as
far, about one football i eld's length (250-340 feet), as do wrens in active devel-
opments.
Moving may be risky, dii cult, and even impossible for some individuals,
but life in the suburbs for forest-dependent species is challenging, and for
males, at least, it is also lonely. The wrens whose territories were somewhat
protected from clearing as developments were created stayed initially but often
disappeared the following year. Several were unable to attract a mate to their
modii ed land.
Movements of another avoider, the Swainson's thrush, were similar to those
of the Pacii c wren. As with wrens, thrushes moved their territories substan-
tially more in areas with active construction than in less drastically disturbed
forest reserves or established neighborhoods. They were, however, less mobile
overall than the wrens. Thrushes moved only i fty meters (about 160 feet)
between years in suburbs and reserves, and just over twice that in developing
neighborhoods. Salmonberry, which quickly covers recently cleared land,
