Return of the Ruby-crowned

We paddle our canoe across Tomales Bay in the drizzle, going in the morning to avoid the usual afternoon winds that kick up the waves. We spend a chilly day sitting by the fire; paddling along the shore; watching loons, tule elk, river otters, osprey, and even a bald eagle. The next morning I wake up to bright sunshine and grab my binoculars and camera. The trees along our small beach are alive with song birds. A tiny, bold bird with a white eye ring and wing bars hops through the hanging moss, coming quite close to me. It's a ruby-crowned kinglet, one of my favorite signs of fall.

Then back in Berkeley over the next few days, I see them everywhere: outside my office in a scrubby little live oak, and another in the juniper bushes by the parking lot.

Then a few days later on my regular bird walk in Tilden Park near Jewel Pond:

And even in my front yard:

You might notice that there are no ruby crowns in these photos. Only the males have red patches on their heads, and even they keep them hidden most of the time. They flash them to signal to a potential mate, or a potential threat.

These lively little birds are quite common in our area from fall through early spring, but then they all migrate to Canada or to high elevations in the Sierra Nevada and the Rockies to breed and nest. In summer, these kinglets are fairly specialized, spending most of their time high in conifers and eating only insects. During migration and in winter, they are more of generalists, living in all kinds of trees and bushes, and adding fruits, berries, sap, and nectar to their diet.

It is likely that the ancestors of migratory birds like these originally spent all their year in what is now their winter habitat. Later they evolved to migrate to their breeding grounds. There are huge disadvantages to migrating: most obviously, the massive energy expenditure to travel that far, but also the requirement to add evolve a new set of behaviors to suit the new, second environment. There must, therefor be an even greater advantage to this adaptation that outweighs the costs. It is likely that this advantage comes from reduced competition for food and nesting sites in areas that are too cold to support most bird species during the winter. Migration behaviors probably evolved gradually, with birds initially traveling shorter distances.

The details of ruby-crowned kinglets behavior during nesting season are not well known. It spends its summers high in tall trees, in relatively unpopulated areas. This bird that is so bold and common here in its winter home becomes mysterious each summer.

LINKS
Ruby-crowned kinglet information from the Cornell Lab of Ornithology
Ruby-crowned kinglet information from Audubon
Tilden Regional Park

Chicken of the Woods and Eucalyptus

The air is dry, with a crisp edge, and buckeye leaves are yellow husks that rustle under foot. Our trail take us into a eucalyptus grove. Strips of fallen bark from the trees cover the ground and lean haphazard against the stripy trunks of the trees. And there, sticking out about ten feet up on one of those trunks, is what we are looking for, a pile of rounded yellow shelves: chicken of the woods. This is the first edible fungus of fall here in the East Bay.

We prod it with a stick and it turns out to be a bit too old and hard to eat, but soon we spot a clump on another tree. It is spongy and moist. Beads of liquid wet our hands. Dinner!

Chicken of the woods, also called sulfur shelf, is a parasitic fungus that feeds on living trees or fairly recently cut stumps. It takes nutrients and moisture from its host. The organism lives within the wood all year long, as a tangle of threads called mycelium. The yellow shelves we picked are the fruiting body, which grows in autumn and releases spores to reproduce. The fruiting body appears so early in the fall, often before any significant rain, because it doesn't rely on moisture directly from recent rain. As the fungus spreads through the tree, it makes the tree more brittle. The tree may eventually fall when it becomes too brittle to bend with the wind.

This species of chicken of the woods (Laetiporus gilbertsonii) grows mostly on oak and eucalyptus in our area, though I have have only seen it on eucalyptus. Eucalyptus trees are not native to California; they were brought from Australia in the 1850's by Australian settlers. In the early 1900's, unscrupulous boosters sold plots of land planted with eucalyptus (mainly a species called blue gum), promising easy money from timber from the fast-growing trees. In just a few years, millions of trees were planted. But this species makes for terrible timber. Most of the stands of eucalyptus are abandoned crops from that era; they don't reproduce well enough in most parts of California to be able to spread to new areas. These eucalyptus groves pose fire hazards, since eucalyptus is extremely flammable. And they don't support many native species. Chicken of the woods is an exception: a California native that thrives in eucalyptus.

Laetiporus gilbertsonii

Another local species of chicken of the woods (Laetiporus conifericola) grows only on conifers,  such as douglas fir.

Laetiporus conifericola

The gilbertsonii chicken of the woods tastes like chicken, meaty and rich, which is how it got its name. The conifericola chicken of the woods has some of that flavor but also has a very strong sour taste. I like it, but some people don't. People's reactions to eating chicken on the woods vary, and not just in relation to the taste: it makes some people projectile vomit! It may be that long cooking reduces that possibility. I sautee it in butter or oil for about five minutes, simmer it in wine and water for another 25 or 30 minutes, cross my fingers, and enjoy.

As chicken of the woods fungus age and get too hard and chalky for people to eat, they are often munched by potato bugs (aka pill bugs, roly-polys) or beetles. Eucalyptus have been in our ecosystem for almost 200 years now. They aren't as deeply entwined with other species as native trees are, but they are a part of our food webs, connected to fungus, people and bugs. Herons and egrets sometimes nest in them. The other day I spotted a red-breasted sapsucker feeding in one. I wonder what new relationships will develop in the next thousand or ten-thousand years.

Even as some stands of eucalyptus are removed to reduce fire danger and to make space for native vegetation, we will continue to live with this species, and with the strange, delicious fungus that attacks it.

LINKS:
Bay Area Mycological Society article about chicken of the woods
One KQED article about eucalyptus in California and another

Mixed Flocks in Fall

"Ka dee dee dee! Chwee deee dee!" The cheery squeaks of a chickadee make me stop and scan the trees. Perky, feathered balls are on the move, popping along the outer branches, hanging upside down to snag a bug.

For a couple of minutes, chickadees are the only birds I see—cute for sure, but also common and not that exciting. Then, a movement catches my eye that registers as different. I look through binoculars, and yes, a bright yellow face streaked with black: a Townsend's warbler.

The longer I stand there, the more movement I see all around. I spot a brown creeper, working its way up the trunk of a large oak, perfectly camouflaged with the bark.

Towhees kick up the leaf litter. Bushtits mingle with the chickadees. A pacific-slope flycatcher flutters out from a branch and back to its perch.

Forest birds often travel in mixed flocks like these. I first learned about this phenomenon in the rain forest in Costa Rica, but it's common here in the Bay Area as well. Mixed flocks allow birds the benefits of foraging in a group—more eyes and ears to spot danger—with less competition for food than there would be in a flock of just one species. Chickadees gather bugs and seeds mostly from small branches and leaves. Flycatchers grab flying insects out of the air. Towhees find their food on the ground.

This is an especially good time of year for watching mixed flocks because our resident birds, such as chickadees, towhees, and creepers, are joined by migrants on their way south, such as Townsend's warblers. Townsend's warblers nest in conifer forests of western Canada and the Pacific Northwest. Some winter in a narrow band along the coast from Washington to Baja, but most travel on to Mexico or Central America. Their lifestyle changes quite a bit in different parts of their year: in nesting season they live high in old-growth conifers forests, eating mostly insects. During migration they come lower in branches of all sorts of their trees, and eat a lot of flower nectar. In winter in Mexico and Central America, many guard trees infested with scale insects that secrete a sugary liquid that the birds eat.

I wonder why the mixed flock behavior evolved for some species but not others. When I notice chickadees, I always scan for other species, but dark-eyed juncos—another of our most common forest species— almost never seem to join mixed flocks. I wonder how a mixed flocks joins together. Do the birds happen upon each other by chance and just stick together? Do they seek each other out using calls? Or start the day in the same area each morning?

Each time I happen upon a mixed flock, the mix of species is different. While chickadees are almost always a main ingredient, sometimes oak titmice, bushtits, or ruby-crowned kinglets form the nucleus. The mix may include woodpeckers, nuthatches, or vireos. A mixed flock is a dynamic and eye-catching example of the interweaving—through competition, cooperation, and micro-habitats—of different species in any ecosystem: the mix of live oaks, bay trees, and ferns along the seasonal creek bed in the canyon outside my work; the spring collage of lupine, poppies, and checkermallow by Volmer Peak in Tilden Park.

LINKS:
Washington Post article about mixed flocks on the east coast
Cornell Lab of Ornithology Information about:

• Chestnut-backed chickadee
• Townsend's warbler
• Brown creeper
• Pacific-slope flycatcher

Tropical Nature: Life and Death in the Rain Forests of Central and South America, a wonderful book where I first read about mixed flocks