Abstract
From 28 Sep to 7 Oct 2012, bird collisions with the glass façade of a commercial building in the centre of Ljubljana were monitored. The observations lasted 45-60 minutes in the morning (7.00-10.00 hrs), around midday (11.00-14.00 hrs) and in the afternoon (15.00-18.00 hrs). Behaviour of all birds and scavengers, which could potentially be looking for bird carcasses in the vicinity of the building, was noted. In 27.25 hours of observation, 16 collisions (3 resulting in death, 13 cases with birds flying away seemingly unharmed) and 19 near collisions, when birds avoided the building at the last moment before collision, were recorded. The total collision rate was 0.59 collisions per hour of observation. All birds that collided with the building, except Feral Pigeon Columba livia f. domestica, were passerines, among which tits Paridae predominated (62.5% of birds that collided with the building). The glass façade functioned as a mirror, reflecting tree crowns from across the street. Data show that most collisions occurred in the middle part of the building during the morning. Among potential scavengers, domestic cat Felis domesticus and Hooded Crow Corvus cornix were observed. The latter regularly flew around the building during the observation period, possibly looking for bird carcasses.