84 Tinarelli, R (1997): La nidificazione del falco cuculo Falco vespertinus nell’Emilia Romagna orientale. − Picus 23: 111−112. Tucker, G.M. & Heath, M.F (1994): Birds in Europe, Their Conservation Status. − BirdLife International, Cambridge: 600 pp. Arrived / Prispelo: 20.3.2006 Accepted / Sprejeto: 5.10.2006 Kratki prispevki / Short Communications Strong agonistic reaction of territorial male Blackbird Turdus merula against its self-image Mo~na agonisti~na reakcija teritorialnega samca kosa Turdus merula proti lastni podobi Al Vrezec Nacionalni in{titut za biologijo, Ve~na pot 111, SI−1001 Ljubljana, Slovenija, e−mail: al.vrezec@nib.si In spring, high level of testosterone in males induces the vigorous territorial behaviour and song production (Catchpole & Slater 1995). However, birds usually try to avoid direct agonistic interactions, since they can cause serious injures. Therefore, territorial males communicate with threat postures and song rather than with the direct attacks (Gill 1995). Usually, both visual and vocal stimuli are important for an aggressive male to attack. However, on 17 Apr 2006 I observed, at Hrastje near Modra`e in NE Slovenia (UTM WM53), a 2Y male Blackbird attacking his self-image in a mirror, although no vocal communication was present (Figure 1). The bird was constantly attacking the mirror through the whole day. When scared, it flew away, but was soon back again repeating its attacking behaviour Figure 1: Strong agonistic reaction of 2Y male Blackbird Turdus merula against its self-image, recorded on 17 Apr 2006 at Hrastje near Modra`e in NE Slovenia (UTM WM53) Slika 1: Mo~no agonisti~no vedenje drugoletnega samca kosa Turdus merula proti lastni podobi v ogledalu, opa`eno dne 17.4.2006 v Hrastju pri Modra`ah (SV Slovenija; UTM WM53) 85 Acrocephalus 27 (128-129): 83−93, 2006 (Figure 1). I made a small experiment and placed a predator dummy, a stuffed Tawny Owl Strix aluco, to see if mobbing or predator-induced behaviour would prevail over social or territorial behaviour as known in some other bird species, e.g. Arabian Babbler Turdoides squamiceps (Sommer & Mundry 2005). At the beginning, the territorial Blackbird inspected the dummy, but later continued with attacks on its own image. When the mirror was removed, the bird came back several times to search for the “intruder”. The search lasted for approximately 15 minutes, and then the male engaged in singing or vocal display. The case shows that the territoriality in mating season can induce, at least in some males, strong agonistic reaction to intraspecific intruders. There is a question, however, whether this is a general phenomenon or is just restricted to some more aggressive or young males establishing their territories. Povzetek Opazovanje drugoletnega teritorialnega samca kosa Turdus merula, ki je 17.4.2006 v zaselku Hrastje pri Modra`ah (UTM WM53, SV Slovenija) silovito napadal lastno podobo v ogledalu. Z agresivnim vedenjem ni prenehal niti tedaj, ko mu je bila nastavljena lutka plenilca, naga~ena lesna sova Strix aluco. Napadati je nehal {ele po odstranitvi ogledala. Primer ka`e na mo~ne agresivne odzive teritorianih samcev v gnezditveni sezoni, zato bi bilo v prihodnje koristno preveriti, ali se pojav ka`e le pri nekaterih osebkih ali gre za splo{en pojav. References Catchpole, C.K. & Slater, P.J.B. (1995): Bird Song. – Cambridge University Press, Cambridge. Gill, F.B. (1995): Ornithology. – W.H. Freeman and Company, New York. Sommer, C. & Mundry, R. (2005): Do social rank and predator type influence the structure of predator-induced calls in Arabian babblers? pp. 30 In: Trilar, T. (ed.): XX. Congress of International BioAcoustic Council (IBAC), Book of Abstracts. – Prirodslovni muzej Slovenije, Ljubljana. Arrived / Prispelo: 19.4.2006 Accepted / Sprejeto: 5.10.2006 The Neretva delta region has probably played an important part in the expansion of the Spanish Sparrow, as this was the source area from where these birds colonized north Dalmatia and the islands further away in the late 1970’s (Luka~ 2004). Relying on his own data and literature reports on only 353 known nests in South Dalmatia, Luka~ (2004) estimates the amount of Spanish Sparrows breeding in the region at around 3,500 − 19,000. As there is little information about Spanish Sparrows breeding in the Neretva delta (Kralj 1996), it is important to publish as much data about the number of breeding pairs as possible. Between 3 − 10 Apr 2006, we travelled several times from Metkovi} to Lake Kuti. Along the 11 km long road between Bijeli Vir and Kuti, a total of 263 Spanish Sparrow nests were counted (no nests were found in Dubravica and Kosa). The distribution of the nests was as follows: in Bijeli Vir (YH16) 186 nests in 21 poplar trees Populus sp., and 2 in 1 willow Salix sp. In Mlini{te (YH16) 21 in 1 plane tree Platanus sp., 14 in 1 mulberry tree Morus sp., and 28 in 4 willows. In single poplars in Mislina (YH16), Bad`ula (YH16, YH15) and Kuti (YH15), 2, 7 and 3 nests were found, respectively. The number of these nests (263) provides information on the breeding period of the previous year (2005). In case some of the breeding pairs built new nests for the second clutch, that meant somewhat less pairs. However, it is not known how many of the nests were lost during the winter, and how many of the nests were overlooked by the observers. Also, a certain number of nests inside the colonies might have been used by other sparrow species (Passer domesticus, The number of Spanish Sparrow Passer hispaniolensis nests in the Neretva delta (S Dalmatia, Croatia) [tevilo gnezd travni{kega vrabca Passer hispaniolensis v delti Neretve (J Dalmacija, Hrva{ka) Jasmina Mu`ini}1 & JenŐ J. Purger2 1 Institute for Ornithology CASA, Gunduli}eva 24, HR−10000 Zagreb, Croatia, e−mail: jasmina@hazu.hr 2 University of Pécs, Institute of Biology, Ifjúság útja 6, H−7624 Pécs, Hungary, e−mail: purger@ttk. pte.hu