Discovery of a big hibernacula of Noctule bats, Nyctalus noctula (Schreber, 1774) (Chiroptera: Vespertilionidae) in the town of Plovdiv, Bulgaria

The current article presents data on the wintering colony of Noctule bats at a river bridge in the town of Plovdiv, Bulgaria. The data were obtained during a rescue operation aimed at saving the wintering colony threatened by repair works on the Gerdzhika bridge over the Maritza river in the centre of Plovdiv. The operation was carried out during the period 26.11.2005 -- 31.11.2005 by volunteers from the Green Balkans Federation, and all activities were coordinated with representatives of the regional inspectorate of Environment and Waters -- Plovdiv and the Wildlife rehabilitation and Breeding center -- Stara Zagora. The bats were using the gaps of the bridge as a shelter for hibernation and the ongoing repair was threatening them by squeezing or burying them under the construction debris. During the rescue the bats were taken from their shelters and transported for a temporary stay to the Wildlife rehabilitation and Breeding center of Green Balkans -- Stara Zagora. The reported minimal number of wintering Nyctalus noctula in the gaps of the Gerdzhika Bridge in Plovdiv is 1035 individuals, this is the most numerous colony registered in Bulgaria to date. The colony consists of 57 % female and 47 % male individuals. cranio-mandibular measurements taken contribute to the data published in “Fauna of Bulgaria”.