San Francisco Bay and nearby Point Reyes and Monterey Bay are famous among birders for the number and diversity of migrant and wintering birds that occur there. What many people may not know is that at least 68 of these bird species breed wholly or largely in the boreal forests of Canada.

The Pacific and Common Loons that spend the winter diving for fish in the ocean waves along the coast in places like Point Reyes and Monterey Bay may have been born and raised in a lake within the Mackenzie River watershed of Canada's Northwest Territories. The thousands of Lesser and Greater Scaup that sometimes winter in Richardson's Bay near Tiburon are similarly dependent on the thousands of small wetlands dotted across the boreal zone of Canada and Alaska. Unfortunately scaup populations have declined by an estimated 40% over the last 25 years but researchers don't know why. San Francisco Bay is also a critically important winter area for Marbled Godwits, hosting as much as 10% of the world population in winter. A large portion of the species' breeding range lies with the boreal zone of Saskatchewan and Manitoba.

Many of the birds that use the area in fall migration are on their way even farther south to spend the winter. The flocks of Lesser Yellowlegs feeding in saltmarsh pools in the Bay Area in September, for example, may continue south to bays and wetlands along the Pacific Coast of Mexico or even farther south. The Golden-crowned Sparrow flocks that arrive at backyard feeders in San Jose and San Francisco areas every October may have whistled their clear songs from a territory deep in the heart of the Canada's Yukon throughout the summer. Some species that raised young in the boreal forest have stopped off to feed in the San Jose/San Francisco Bay region on their way to wintering grounds in Central and South America. For example, a Yellow Warbler stopping at a wooded park in August may have departed Canada in July and be Central or South America by September.