Geography Reference
In-Depth Information
spring. Where earthworm invasions are substantial, the breeding output of
ovenbirds is low. In part, poor reproduction is due to a reduced ability of
ovenbirds to hide their nests on forest soils no longer cloaked in dead leaves.
But a reduced abundance of invertebrates, many of which are outcompeted by
the invasive worms, also makes it dii cult for ovenbirds to capture enough
food to feed large broods.
Not all parts of the decomposition network are functioning at top speed in
urban systems. The loss of large beetles from cities extends to important
decomposers—carrion beetles and dung beetles—at least in New York. In the
greater New York City area, i fty species of these busy, burying beetles exist.
Only twelve species live within the city, and only four live in Manhattan. Why
should we care about these animals that we rarely even notice? Well, they're
not called “carrion” or “dung” beetles without good reason! Some scurry
about rolling up balls of dung—from horses, humans, dogs, deer, opossums,
and maybe even geese—laying their eggs inside the balls and burying them.
Others lay their eggs in small animal cadavers and then entomb them beneath
the soil. When the beetle numbers are reduced, the dung and the dead fester
aboveground, for anyone to experience. As this mess rots and stinks, it at-
tracts l ies that l y in for a feast, lay their eggs, and buzz of to visit people and
their food.
Not all insects respond as predictably to urbanization as do the beetles.
Butterl ies are more complex. In Osaka, Japan, butterl y diversity peaks just
beyond subirdia, where forests occupy about 70 percent of the land, frequently
edging up to meadows, buildings, and gardens. There, an astonishing seventy-
eight species of butterl ies seek l oral rewards. In California and Ohio, Dr. Rob
Blair also found butterl ies most diverse in suburban, or slightly wilder, set-
tings. But in Singapore, South Africa, Brazil, and the United Kingdom, no
peak in butterl y diversity at intermediate levels of urbanization has been de-
tected. Rather, diversity declines steadily from a high in natural areas outside
