Aggressive behaviour of Robins Erithacus rubecula (Passeriformes, Muscicapidae) at watering places in the forest steppe zone of Ukraine

Abstract

283 The purpose of this research was to study interspecific and intra-specific aggressive reactions of Robins (Erithacus rubecula L.) at watering places in natural and anthropogenically pressured areas. The study took place in Kaniv Nature Reserve, Cherkassy region, in May-June 2010, 2012 and 2014 and the state dendrology park “Oleksandriya” of the National Academy of Science in Bila Tserkva. The observation of the birds’ behavior was performed using the ethological methods of “total observation” and “continuous logging”. In order to calculate the critical distance at which a bird shows aggression, the watering areas studied were divided into 1 x 1 m squares. It was found that aggressive intersspecific actions of Robins were more frequent in the natural habitat of Kaniv Reserve while intraspecific aggression was more frequent in the dendrology park. It was noticed that Robins responded aggressively to 12 species of birds in the Kaniv Natur Reserve site. Those species were: Song Thrush (Turdus philomelos), Blackbird (T. merula), Great Tit (Parus major), BlueTit (P. caeruleus), Marsh Tit (P. palustris), Chaffinch (Fringilla coelebs), Hawfinch (Coccothraustes coccothraustes), Icterine Warbler (Hippolais icterina), Wood Warbler (Phylloscopus sibilatrix), Blackcap (Sylvia atricapilla), Collared Flycatcher (Ficedula albicollis) and Spotted Flycatcher (Muscicapa striata). Most often, aggression was directed to individuals that were already at a watering place rather than birds which arrived after the Robins. Besides, Robins frequently initiate aggressive relations. An inverse correlation of aggressive acts and the size parameters of the species, which were objects of Robins’ aggression, was observed. A success rating of Robins’ defence and attack in aggressive relations in Kaniv Nature Reserve was established: Robins were always successful in protecting its territory or attacking an Icterine Warbler and Chiffchaff, and always fails in defending agianst or attacking a Blackbird. The rating in contact with Spotted Flycatcher was zero. The critical distance of aggressive behaviour in intraspecific contacts at watering places was 40–50 cm, while for interspecific contacts it varied from5 cm to2 m. Our research emphasizes the importance of long-term research and multivariate approaches for understanding the complexity of dominance relations in birds.