…jacks of all trades

A black-billed magpie harassing a hawk owl. Photo by Bob Armstrong

Juneau sees magpies in fall, winter, and early spring, outside of the nesting season. They come to us from nesting areas in the Interior. They are not strong fliers, but that long, elegant tail allows them to make quick changes of direction. These flashy birds sail across the roadways, check out roadkills and dead salmon, raid some kinds of bird feeders, and fossick about the edges of wetlands and woods in search of something edible. Magpies can eat ‘most anything, be it animal or vegetable. Sometimes they pick ticks from the hides of moose and deer. They eat fruit, catch mice, and gobble up beetles and worms, regurgitating the indigestible bits in pellets. When an eagle holds down a salmon on the shore, magpies team up to rob it: one magpie tweaks the eagle’s tail feathers, while another one snags a chunk of salmon.

These are black-billed magpies (Pica pica). The species is currently considered to comprise about twelve subspecies, spread across much of the northern hemisphere. The North American subspecies nests in the dry, cool parts of the West, geographically isolated from the other subspecies. There are other geographically isolated subspecies—one in northeastern Siberia, one in extreme northwest Africa, and one in (of all places!) a small mountain range in Saudi Arabia. All the others are found in Eurasia, from the UK and Scandinavia southeastward to south China and Thailand.

Some ornithologists think that black-billed magpies may have inhabited North America long ago, before the last major glaciation. They got wiped out, perhaps by environmental changes associated with glacial advances. They then recolonized our continent, coming from Asia over the Bering land bridge.

Down in the valleys of southern and central California lives another species, the yellow-billed magpie (P. nuttalli). These birds may constitute a relict population left over from a time before the last major glaciation. They are quite different the black-billed species in life history, physiology, and social behavior. Despite all the differences, yellow-bills are thought to be more closely related to North American black-bills than those black-bills are to the Eurasian forms. It may turn out, with more study, that the North American black-bills are really different species than the Eurasian ones, which have quite different behavior and vocalizations.

Magpies form pairs that are ostensibly monogamous, but extra-pair copulations occur (as in many other songbirds), especially involving older males. They do not defend large, multi-purpose territories, but only defend an area around a nest. Our magpies like to nest in trees and large shrubs, but prefer to forage in open country. They build large, domed nests of sticks and line them with mud and grass. It can take six to ten weeks to build this structure—no small investment! Both male and female work on the nest, the male mostly with sticks and the female mostly with the lining.

The female lays an average of about six eggs (but up to nine) and incubates the eggs for about eighteen days; the male brings food to her as she sits. Incubation begins before the last egg is laid, so hatching is not synchronous and the chicks are therefore of different sizes. Chicks stay in the nest, fed by both parents, for about four weeks. There is strong sibling competition for food, and when food is scarce, the smaller chicks may starve (or be killed by bigger chicks). As a result, the number of fledglings per nest can be markedly smaller than the number of eggs.

After the chicks leave the nest, they are fed by the adults for six to eight more weeks, and sibling rivalry continues. When they become independent, the juveniles (especially males) generally form winter flocks, with a strong dominance hierarchy.

Females mature at age 1 year, males usually at age 2 years. But average life expectancy is not great: females 2 years, males 3.5 years. So, on average, each bird only gets about two nesting seasons and thus two chances to rear young.

Magpies belong to the corvid family, along with ravens, crows, and jays. Many of the corvids, including magpies, have a fascinating behavior known from only a few other animals (such as elephants). They conduct what are called ‘funerals’. If a magpie dies, the first bird to notice the body calls in other magpies, and they all gather around the corpse for a short time. A bit like conducting a wake in human society, although the exact function of these funerals is not known.


To John Muir Cabin

late flowers and early arrivals

By sheer luck, a late October ramble on the Auke Nu trail to the John Muir cabin found us in partial sunshine. Some of the boardwalk was even rather dry, although most of it was still very wet and slippery. All the usual mudholes were still there, of course, and we can only hope that someday they will be filled with gravel. A major erosion channel is developing along the trail near the trailhead and a large spruce has tipped up its roots, exposing its very shallow root system.

A few dwarf dogwood and bog laurel flowers stubbornly persisted, but they waited in vain for a passing bee or fly to do the pollinating. Blueberries still hung on the bushes—we just don’t get enough migrating thrushes and wandering bears or other critters to clean out the berry crops and accomplish all the potential dispersal of seeds, especially in a year of bumper berry crops like this one.

The John Muir cabin has been nicely renovated. New floor, new table, new bunks upstairs and down, and a nifty spiral staircase to the loft. A door at the top of the stairs helps control heat distribution, and an escape hatch, with ladder, provides an emergency exit from the loft. New windows offer great vistas and ventilation if needed. There are lots of pegs for wet rain gear and grab bars for swinging into the upper bunk.

The wood stove now sits in the middle of the floor, with space around it for folks to move about. The propane heater works well. And there’s a brand new outhouse, complete with gravel walkway from the cabin. Pretty cushy!

October is the mating season for porcupines. The babies of last spring are still very small, but they are now on their own, chowing down on the remaining herbage before shifting to a winter diet of bark. So their mothers are ready to mate again. If you hear strange calls coming from up in the tree canopy, and you are pretty sure it’s not an unusually inventive raven, it might be a male porcupine announcing his availability to nearby females or perhaps a couple of males squabbling over mating privileges.

Winter arrivals from the Interior have been here since September. Slate-colored juncos now mix with our local Oregon juncos at feeders. Black-billed magpies call raucously, visit seed feeders, and are constantly on the lookout for something better. They are good scavengers, and salmon carcasses are high on the list of favorites. Just recently, I saw an eagle perched on a rock in the Mendenhall River with a dead coho at its feet. Hanging around, just out of the eagle’s reach, was a hopeful magpie, waiting to dart in for a morsel or two. No doubt there were a few more magpies lurking nearby.

Postscript on the Bear Creek Dam in Douglas:

Some weeks ago, I wrote about the early history of this dam. Here are some tidbits about later history there. The CBJ water department tells me the dam was decommissioned in 1985, when Douglas went onto the city water system. No one currently at the water department knew about early maintenance activities at the dam, but some Douglas residents remember that CBJ occasionally cleaned the walls of the reservoir when water was low. At low water, residents could hike up the canyon above the concrete dam and find an old log dam, presumably left from the abortive attempts to mine that area. When the reservoir was full, this was a popular spot for picnics and swimming in summer, and for skating in winter. Between the dam and 5th Street is an old viewing platform, reportedly sponsored by Gastineau School for access to the creek and class projects.

The dam is reported to be structurally sound still, and the CBJ water department goes up there once a month to make sure the tailrace is clear of obstruction, so water flows freely through the bottom of the dam.