A robust bird population on a California university campus shows it\'s possible to create a green wildlife haven within a dense urban area, researchers say. The bird population on the University of California, Berkeley, campus has remained surprisingly diverse over the past 100 years despite a century of changes to its urban surroundings, a university release reported. A study published in the journal The Condor identified 48 separate bird species in an 84-acre portion of the 178-acre central campus, researchers said, a greater number of species than the 44 and 46 recorded during surveys conducted in 1913-18 and 1938-39, respectively. \"The presumption going in was that we would see a steady decline in the number of species because the campus, like any urban environment, has been heavily modified, with more buildings and 15 times more students,\" Rauri Bowie, a professor of integrative biology, said. \"But despite everything that has happened on campus in the past century, we find absolutely no evidence for that.\" Researchers said the finding make them optimistic about the ability of urban green spaces, and college campuses in particular, to serve as islands of diversity. \"It is time for urban green spaces to be thought of not only as hospices for diversity, but also as potential nurseries,\" the researchers wrote in The Condor.