Geography Reference
In-Depth Information
bird territories in his neighborhood. Gone were the most common birds of
the 1940s. There were no pairs of red-eyed vireos, ovenbirds, scarlet tanagers,
hooded warblers, Acadian l ycatchers, or wood pewees. In their places were
cardinals, mockingbirds, song sparrows, blue jays, starlings, gray catbirds,
American robins, and house sparrows. In total, the density of birds increased
(from 187 to 263 territories), and the number of species rose by six (from
twenty-three to twenty-nine). The avian community grew as it was trans-
formed; eleven species were lost while seventeen were gained.
A similar story played out across the Atlantic Ocean in London, England.
There, in the central forty square miles of the world's twenty-third largest
city, ornithologists surveyed birds in 1900 and again in 1975. Rather than
documenting a startling decline in the variety of birds, they were surprised to
i nd that nearly all birds known from 1900 remained in London seventy-i ve
years later; only i ve species were lost. To of set these losses, twenty new spe-
cies colonized the city, substantially increasing London's bird riches from
twenty-i ve to forty species. And the number is increasing still; the 2008-2012
London bird atlas project recorded sixty species! Reduced pollution, im-
provements in public attitudes and actions on behalf of birds, and conserva-
tion ef orts to restore bird numbers and embellish bird habitat in city parks
contributed to the renewal of London's birdlife.
In Perth, Australia, birds have not fared quite as well. In the central but
large and wild Kings Park, ten species known in 1937 were lost by 1986. Most
species survived within the park and held their own for the i ve decades
spanned by the study. But only three new birds colonized the park during this
time, so the number of species dropped from thirty-nine to thirty-two. Tram-
pling of ground vegetation and enhancement of nectar, fruit, and water in
suburban gardens likely caused the changes in Perth. Birds that pounce on
ground insects such as the sacred kingi sher and scarlet robin were among
those lost, whereas species that fed above forest openings and on ornamental
fruits—such as the welcome swallow and rainbow lorikeet—were gained.
