165 ACTA ZOOLOGICA BULGARICA Acta zool. bulg., 59 (2), 2007: 165-172 Study on the Home Range of the Resident Female Otter (Lutra lutra), (Carnivora, Mammalia) in South-East Bulgaria Dilian G. Georgiev 1 1 Department of Ecology and Environmental conservation, Faculty of Biology, University of Plovdiv, Tsar Asen St. 24, BG-4000 Plovdiv, Bulgaria; e-mail: diliangeorgiev@abv.bg Abstract: The home range of the otter (Lutra lutra) was studied for the irst time in Bulgaria. The approximate home range of one resident female otter in the region under study was 2.2 km bank side of an artiicial lake, 6.0 km river length, and 2.5 km canal length. The home range parts mostly preferred for placing the marking sites were the ones with vegetation cover, soil banks and no pollution. Different combinations of a complex of negative factors were essential for avoidance of scat marking by otters in the study area. Most of the sprainting sites in the study area were situated up to 1 m height above water surface and in the stripe of 1 m towards the bank line in and out of the water. In the otter home range studied, sprainting sites with occasional use were most abundant, followed by those of frequent and intense use. The highest association was computed between the intensively marked sites and the presence of dens. Most dominant sprainting site type was the marking throughout the home range without any speciic stimulus considered just “marking the home range”. Ten different substrates used for marking over were deined in the region. In the study area the dens registered were always placed in the root systems of tree species. During the study period 2 active dens always occurred. Key words: Mustelidae, habitats, marking sites Introduction The home range size of otter (Lutra lutra (LInnAEUS, 1758)) and its use varies in relation with the habitat type and with a variety of limiting factors such as food supply, human disturbance, pollution, vegetation cover, and climate conditions (SokoLov, Rojnov 1979, MASon, MAcDonALD 1986, MASon 1995, kEMEnES, DEMETER 1995, SIDoRovIch 1995). The ecology of otter in Bulgaria is poorly known (SPIRIDonov, SPASSov 1989, PEShEv et al. 2004). our aim was to investigate the size and structure of the home range of resident female otter with the other individuals which temporarily inhabit it (ERLIGE 1967, 1968) and their habitat and environmental preferences for marking in the study area, and to represent a model, which could be used in the future monitoring programme for the species in the country. We also wanted to throw some light on the problem of the meaning of the marking activity, which is still not clearly elucidated (chAnIn 2003a). otter’s marking sites (the so called “sprainting sites”) are prominent terrestrial sites at speciic locations through their home ranges where animals deposit their scats (“spraints”) (kRUUk 1992) and are often used for species monitoring (chAnIn 2003B, MASon, MAcDonALD 2004). Study Aea The area of study was situated mostly in the town of Stara Zagora (South-East Bulgaria, UTM grid: Lh80, LG89, LG99). It was placed in a park ranging