Female first seen trying to climb a tree trunk but repeatedly falling off. After the last fall she remained still for nearly 10 minutes, but then started climbing again, very rapidly, till almost out of sight. I noticed some wild fluttering in her vicinity and at full zoom I could make out that a pair were mating. When I returned after about 15 minutes, she had moved further up and another male (or the same one again?) appeared and there was another mating.