The next couple of months provide the absolute best birding on the Cape and Islands. Birds all over North America are on the move, and, beyond the embarrassment of riches that is our normal flood of migrants, the potential for rarities is very high now. Take, for example, the two Yellow-headed Blackbirds that were discovered walking tamely around Kalmus Beach in Hyannis over the weekend. These striking blackbirds are a strictly western species during the breeding season, but one or two misguided