I worked in Jersey City, NJ's third-largest city (some would say second-largest), from 1999 until my office moved to midtown New York in 2009. The office building was on the Hudson River and had once been a freight building for goods brought east by railroad. It was surrounded at one time by other freight buildings and railroad tracks. When it became an office building the tracks were paved over and taller buildings started going up.
The area continued to change in the 10 years I worked there. Tracks were put IN, this time for a light rail system. Larger office (and, later, residential) buildings went up. But for a time, within walking distance, you could still find large vacant lots and large plantings in residential yards and along commercial sidewalks. That's where the birds were.
I knew things were going to be interesting the first spring I walked along the Hudson and found a red-eyed vireo in a tree. It looked as surprised to be where it was as I was to find it.
At other times, in another weedy field a block from my office, I found more than just the usual sparrows, starlings and pigeons. In winter there were white-throated sparrows. In spring there were black-capped chickadees and American redstart. One summer I found a kestrel. In fall, a northern parula hung around for three days and I found four winter wrens. (I've seen more winter wrens in Jersey City than I've seen in the woods.)
Farther away I found a weedy field full of hungry American goldfinches. Van Vorst Park has had a lot of birds over the years I visited, including rubycrowned kinglet, Tennessee warbler, Blackburnian warbler, eastern peewee (calling from a tall tree) and, during a hot summer when sprinklers watered the gardens, a pair of mallards.
What was once New Jersey's tallest building, 101 Hudson, has hosted a nesting box for peregrine falcons, which have raised several generations thanks to Jersey City's generous pigeon supply. The screen shot below is from http://www.state.nj.us/dep/fgw/peregrinecam/jcp-still.htm
Along the Hudson I'd find brant and canada geese, redbreasted merganser and other ducks. Landscaping at a waterfront apartment complex at the end of Warren Street during spring migration was very good for warblers - I had black-throated blue, yellow and common yellow-throat on one visit - and herons, including a little blue heron.
But it all changed after Sept. 11, 2001. Businesses displaced by the destruction of the World Trade Center started moving to Jersey City (temporarily, as it turned out). The high rents of New York drove people to the factory lofts and new apartment towers. The weedy fields, including the one a block from the office and those along the light rail tracks, were filled in. No fields, no birds. Even Van Vorst park lost half its garden space to a dog park. Those living closer to the canal park used that for a dog run, their unleashed mutts scaring the birds out of view.
Birding became impossible. So I was not that upset when we learned the office would be moving to another concrete jungle, midtown Manhattan. Without the birds, Jersey City was just another big, ugly city.
The only thing I have missed is the mighty Hudson River out my window.