Regulation of population size of street pigeons in Ljubljana, Slovenia

Problems related to street pigeons in cities are relevant from the aspect of environmental hygiene, as well as the epizootic risk. In Ljubljana Slovenia, a research study is being performed with the purpose of reducing the number of pigeons by contraception and to achieve improvement in the health status of the population. A total of 2038 pigeons were supplied with hormonally treated maize Ornisteril (Virbac) daily during the intensive mating season at several feeding sites in Ljubljana. 293 birds were caught for clinical, parasitological, microbiological and serological examinations of the health status of the pigeon population in Ljubljana. The results of the treatment with Ornisterilâ show that the number of pigeons in the wider city centre was decreased by 24.3% in three years. A strong infestation of ecto- and endoparasites, mostly Columbicula columbae and Trichomonas gallinae was present. The immunological reactivity of pigeons to Chlamydophila psittaci, was examined and it was shown that the number of positive reactors decreased by 23% to 11.8%. No clinically diseased pigeons were found. Analyses to determine the presence of Salmonella sp., indicated 4.3% (6 cases) incidence of isolation of Salmonella strain bacteria in pigeons in 2000, i.e. S. sinthia. In one case S. typhimurium was isolated from the cloacal smear. In 2001 no bacteria of the strain Salmonella were found in pigeons