The Greater San Francisco Bay Climate
Spring Birds migrating from more southerly latitudes begin
showing up as early as mid January and extend through June.
During this period shorebirds, now in bright breeding plumages,
fatten up in preparation for the long flight to their northern breeding
grounds..Many of them remain in California through March or April
before heading out. The forests reach the peak of activity in May
and June with breeding displays and nest building activities of
songbirds. Wildflower blooms peak in the valleys, coast side and
desert about March/April, on into May and June in the foothills and
higher elevations. In the coastal mountains black bears begin
stirring out of their long winter nap around February/March hungry
and foraging for food. Northbound California Gray Whales can
occasionally be seen making their way back to the Bering Sea and
Gulf of Alaska from Baja but are typically a little further off shore on
this leg of their migration. Marine mammal colonies are still very
active with the adults in the early stages of parenthood at this time.
butterflies flutter from bloom to bloom in search of nectar while
Ospreys make spectacular dives for unsuspecting fish.
Swallows amass by the hundreds and sometimes thousands
scooping up flying insects on and above lakes, ponds and
meadows. Residents bird such as the Wrentit, Towhees,
Vireos and Brown Creepers, along with a large variety of
Woodpeckers are busy raising their fledglings in the coniferous
and broad leaf forests. Southern seabirds such as Brown and
American White Pelicans fly up from the south perhaps to enjoy
the cooler weather or better fishing and mingle with gulls,
Cormorants, Avocets, Stilts & Herons. The coastal areas
cooled by marine influence provide a respite from the summer
heat while the Sierra and Coastal mountain ranges offer spring
like conditions in the higher altitudes.
Fall The first signals of the fall migration actually happen in late summer
as shorebirds begin trickling in to the coastline and estuaries in late July.
This is the most exciting time of year for us as nearly 20 species of
migrating raptors are funneled along the coast through the Marin
Headlands using the thermals to gain elevation before crossing the open
waters of the Golden Gate. During the peak of the hawk migration in late
September sometimes hundreds of raptors can be witnessed in a single
outing. At this same time of year the shrubs and trees become alive with
migrant songbirds either in route to more southerly latitudes or setting up
shop for the winter. Early fall rains can bring many unusual birds that will
take shelter in woodland areas along the coasts and bays. This is also
the best time of year for observing the rutting behavior of deer and elk.
The California Gray Whales can be seen on their southbound migration
starting in November while the Monarch Butterflies start showing up on
land. Fall colors begin in September, peak in early October in the
mountain areas, late October to early November at lower elevations.
Winter Habitat and seasonality bring constant change to the
diversity and abundance of species in the area. Winter has the
greatest variety of birds as many fall migrants stay on to enjoy
the moist, relatively warm winter and join the resident birds like
the California Quail. Millions of ducks, geese and grebes
descend from the north through the Pacific Flyway to over-
winter in the Klamath and Mono Basins, Central Valley and San
Francisco Bay estuaries. This is also the peak time to observe
marine mammals as they re-establish historic rookeries along
the Pacific coast. Depending on when the first heavy rains
begin, Steelhead Trout, Chinook and Coho Salmon begin their
epic trip to spawning grounds. These fish can occasionally be
seen in the coastal streams and rivers throughout Northern and
Central California during this time of year.
|Nature's Calendar - California