Most of the rural parts of New York City were developed by the early 20th century, and its air and water quality suffered. Ornithologist Ludlow Griscom was critical of urban developments which destroyed bird habitats, and noted decreasing populations of some species as well as a reduction in the number of birds which breed in city parks. Several birds once known to breed in the city, like short-eared owls and upland sandpipers, have stopped due to the encroachment of human activities and destruction of their desired habitats. Even in the mid-20th century, continued development and overall reduction of open space exacerbated population decline.
