Text and research by Bay Nature staff.
Change is Hard (and Soft)
Life starts out at the pebble scale for a common green darner dragonfly nymph (Anax junius). Once hatched from a minute oval egg laid inside plant tissue, a Bay Area nymph spends winter in its pond, lake, or slow-moving creek corner breathing through rectal gills (yes, through its butt!) and hunting voraciously as it grows. One favorite food is the translucent larvae of midges. Sometimes called glassworms, they twitch and squirm to move through the water, catching the very large and bulbous black eye of green darner nymphs. With the worm in its sights, the nymph juts out its cash register-drawer-like lower jaw, skewering the larvae, and in goes the snack.
The inflexible outer layer of the nymph’s skin, called an exocuticle, becomes tighter as the nymph grows. During a brief 10-minute struggle, it breaks through and sheds its too-small skin. The nymph expands, and the tender new outer layer hardens in the next few hours. The creature does that up to 13 times, until it’s almost two inches long. And we thought our winter was rough.
Skunk Season is Real
In the Bay Area, as male striped skunks (Mephitis mephitis) set out in January or February to find mates, they’re on the move and covering miles of ground. A male looking for love travels at night and you may well see him if you’re out and about too. He’s not looking for just one mate and will go from den to den courting. When he encounters a female who won’t have him, she says no the way skunks do. You’re not imagining that extra-skunky smell in winter.
I use our winter’s thick gray sky as a mnemonic to remember that it’s gray whales (Eschrichtius robustus) swimming past us in December and January en route to Baja, where they’ll mate or give birth and join in what amounts to a big whale party. Soon after, some of those grays begin their 6,000-mile return journey north to Arctic feeding grounds. Others stay south longer. You’ll know the return migration is wrapping up when mothers with nursing calves swim through starting in late winter, sticking close to shore, bringing up the rear.
That’s an E.E. Cummings turn of phrase: mud-luscious. He put it in a poem about springtime and puddles, but for West Coast mud, it’s all about winter and the season’s especially low tides. When the Pacific inhales San Francisco Bay water twice a day, it unveils a blackish-brownish, slobbery banquet of Bay mud, full of critters that wintering shorebirds scramble to devour. Geologists call the original lining of our San Francisco Bay shores—a mix of clay, organic matter, silt, and sand less than 11,000 years old—Young Bay Mud, and it contains multitudes.
Get Off Me
Winter is a quiet season. But not when you’re an adult California toad (Anaxyrus boreas halophilus) that has just shaken off hibernation and is ready to join the mate-finding melee. In ponds around the Bay, males crawl on the backs of other toads and grab tight. If the squeezed toad calls out, it’s to say, “Get off me, dude. I’m a dude.” The noise adds up; it could pass for a timid flock of geese. But amid the chorus, males and females eventually find each other, and life goes on.
Hibernations are On to Something
When a large mourning cloak butterfly (Nymphalis antiopa) wafts by in Bay Area woods during winter, its life up until this point, to us, is a bit of a mystery. It could be a local that emerged in all its winged adult glory in fall. Or it might have left its chrysalis in the Sierras during late summer, then flown toward the coast. Regardless, a wintertime mourning cloak is an adult butterfly that has recently woken up: these adults hibernate. They are also among the world’s longest-lived butterflies, capable of surviving up to nine months on the wing. Coincidence?