Gossau 18.04.16

When I arrived to the roof, males and females were on the roof; one of the males was near the edge and the other one was behind the skylight; both females were sat on the nest. Some minutes after, the male that was near to the roof edge walked to the male near the skylight; the males fought, then each one went to one side of the roof. One of the females left the nest for some seconds, she went to the opposite side of the roof and came back. The other female stayed sat on the nest the whole time.