Urbanization in general and the spread of industrial construction into natural areas can seriously reduce animal populations. The effects often reach beyond the actual point of impact. We monitored wetland bird populations in a nearby Natura 2000 area during the construction of the new Vuosaari Harbour (Helsinki, Finland) in 2002–2011. The harbour was built less than 300 m from a bay, Porvarinlahti, and a railroad bridge was built to cross Porvarinlahti. We compared the wetland bird populations before, during and after construction to evaluate whether the changes observed were linked with the construction work in the nearby harbour area. The numbers of species and territories varied between years and subareas, but we found no clear effects of harbour construction on bird population trends.