By Carrie Peyton Dahlberg cpeytondahlberg@sacbee.com The Central Valley fixture could be on path to extinction For tricolor blackbirds that swoop and gather in Central Valley fields, the past breeding season turned unexpectedly into a nearly silent summer. By the tens of thousands, the birds courted, built nests and waited – then abandoned nests en masse as females failed to produce eggs. Robert Meese, a UC Davis researcher who tracks the trademark California bird with its blaze of red and white on the wings, hopes biologists are seeing just a temporary setback, fueled by dry weather that depleted a vital supply of insects. "If this is the beginning of a trend rather than a one-time event we might really be in trouble with the tricolor," said Meese. "The bird is making its last stand, and it's making its last stand primarily in the Central Valley."