A little stroll on Black Mountain this morning in connection with a talk on the birds there next week. I was preparing to preach to the text: Small insect-eaters found there in non-breeding months will probably be associated with a mixed
species flock. There were a few such flocks about and a good one on the precipitous southern slopes with more than 30 birds. I remember hearing the view that the Yellow-rumped Thornbill was the nucleus of such flocks and perhaps it is in some places but
on Black Mountain it is surely the Buff-rumped Thornbill/Grey Fantail combination, the YRT being something of a rarity there. This is supported by Harry Bell’s early work on MSFs (Emu 80 p227), also on Black Mountain as it happens.
