While October provided a non-stop rare bird show on the Cape and Islands, November proved a little quieter, before going out with a bang last week. Two Sundays ago, a biking birder on Nantucket flushed a nondescript gray bird from a dune near Low Beach. This catbird-sized mystery bird with a spotted breast perched up just long enough to reveal that it was, in fact, a Sage Thrasher, representing the first ever record, not just for Nantucket, but for all of the Cape and Islands. Only three other