The robins' dusk chorus ran from about 7:15 to 8:00 this evening. This is what might be called passive territorial singing--the birds take positions in the sunlit tops of trees, no bird nearer than around 250â€² from any other. They then run through their repertoire until, presumably, they get tired of hearing their own voices & head off to roost. Not all of them I heard this evening were necessarily males, as has been commonly thought. Recent research shows that females sing this way too. The moon is waxing gibbous, not quiteÂ Â¾ full. It looks like it will reach its zenith tonight around 9:30, just after passing over the gap between the two biggest maple trees in the yard.