"It's the most urbanized wildlife refuge in the national system," says refuge manager Dick Nugent, pointing out the skyline of the nation's fifth- largest city above the trees.
On the fringes of Philadelphia - in specks of wilderness like Tinicum and the Schuylkill Center for Environmental Education in Upper Roxborough - endangered bald eagles and peregrine falcons rest in flight.
Pairs of peregrines nest on the bridges over the Delaware and Schuylkill rivers. And below, in the Delaware, threatened fish like the shortnose sturgeon swim up the tidal river to spawn.
Although these species are here, they are not here in abundance. The continued threats to their habitats are endangering their survival.
"If you don't save the habitat, you're not going to save the species," says Richard James, director of the Schuylkill Center. ". . . You're just squeezing more and more animals into less space, and the problem is that somebody has to go."
In back yards and parks, here and across the country, once-commonplace songbirds are becoming more rare as forests are cut back, both in North America and in Central America where they winter.
Worldwide, species after species of plants and animals are plunging to extinction as humans clear wetlands and forests for timber, for croplands, for highways or development.
And from the remaining unspoiled slivers of the East Coast to the threatened timberlands of the Pacific Northwest, the push for salvation of species ranks near the top of the environmentalists' and conservationists' concerns.
"We want to save as much of the diversity of life on this planet as we can," says Clark N. Shiffer, endangered species coordinator for the Pennsylvania Fish Commission. "The key to that is saving the habitats on which they depend."
The shreds of habitat that serve as home for a struggling species can be strange indeed.
