Owls and shrikes

hunters on the wetlands

On a damp morning at the end of November, I wandered out on the wetlands near the golf course. There were rumors of short-eared owls foraging in the meadows and I hoped to watch one in action. They commonly pass through the Juneau area on their seasonal migrations, especially in the fall (I think), and occasionally a few may stay the winter.

Short-eared owl. Photo by Kerry Howard

Some short-eared owls that nested in western and Interior Alaska were marked and followed to their wintering areas. Most of the marked birds went south on the east side of the Rockies, but some went along the coast. Winter quarters were spread from Montana to Texas and California to Kansas. Spring migration routes seem to be less well known.

About those short ‘ears’: they are not for hearing at all. They’re just little tufts of feathers that can be erected, presumably as some sort of social communication. The functional ears are asymmetrically placed on the sides of the head, which helps with pin-pointing prey locations.

Short-eared owls are open-country birds, nesting and hunting in tundra and grasslands. Unlike many owls, they often hunt during the daylight hours. Their main prey items are voles and other small mammals, often swallowed whole, but they also capture birds, commonly tearing off the wings before swallowing. Undigested remains are coughed up as pellets (so handy for curious naturalists who like to know what they were eating).

Shortears hunt chiefly by coursing low over the meadows, occasionally hovering for a closer inspection. The wings look big compared to a relatively small body, and indeed this species has low wing-loading. That is the body mass (technically, not quite the same as weight, but close enough for many purposes) divided by the wing area. Those long, broad wings carry an owl smoothly and gracefully over their hunting grounds. The low wing-loading is said to enhance aerial agility, allow better hearing while in flight, and reduce detection by prey.

Owl spotting wasn’t good that morning, though lots of hopeful photographers were out there. I didn’t see an owl in flight or perched on a stump but, guided by some friends, I saw one that had been dead for a few weeks. This bird apparently had been shot by some yokel with more ammo than brains—a wanton, useless act of vandalism that—in addition– certainly reduced potential pleasures for wildlife watchers of all sorts. The body was carefully tucked up in a niche under a stump, maybe just to hide the evidence, but I’d like to think that someone had sympathetically said Rest In Peace.

That was a sad finding, but there was also a good sighting—of a northern shrike. It perched on the long-stranded stumps and logs (with their lovely gardens of lichens and mosses), moving from one to another. Shrikes commonly hunt from elevated perches, most often in non-forested habitats. They eat mainly arthropods (e.g., beetles, grasshoppers, and bees from which they remove the stinger and venom gland—or at least the experienced adults do) in summer. However, in winter they eat more small mammals and birds, often killing these vertebrates with a neck bite. Shrike bills are stout and armed with not only a sharp hook, but also two smaller teeth on the upper bill that have matching notches on the lower bill—the better to break necks, tear flesh, and crack the exoskeletons of insects. Most prey is swallowed whole or in large pieces, but shrikes are said to lack crops, so they cough up undigested remains quite frequently.

Northern shrike. Photo by Kerry Howard

Shrikes are sizable songbirds that can catch prey larger than themselves. They are often called butcher birds, presumably for their habit of wedging or impaling prey; this helps hold the prey for dismemberment and also stores food for later consumption. In fact, the name for the genus of shrikes is Lanius, from a Latin word for butcher. There are reports of nest sites surrounded by scattered stashes of impaled prey, a larder for feeding chicks.

Shrew, stashed by a northern shrike. Photo by Gina Vose

This species of shrike nests in shrubby, semi-open habitats all across the north, beyond the boreal forest. They migrate south for the winter and are then found widely scattered across the country. Occasionally they exhibit population irruptions, when large numbers of them appear in some winters, at least in some areas. Such irruptions in other species are commonly related to food shortages, but for shrikes, the reasons behind the irruptions are not clear. Here, we see shrikes only occasionally, mostly on migration but sometimes in winter. The shrubby flats on the shores of Mendenhall Lake and the wetlands offer the right sort of habitat locally. Seeing this one was a treat. Its mostly gray plumage is not fancy, but the black and white patches on wings and tail were flashed conspicuously when it flew. Then it looked like a different bird altogether.


Cheering notes

floral memories brighten a gloomy winter

As I sat here on yet another gray and drippy day in mid-January, grousing futilely and needing a cheering thought, there popped up a memory from my old life in the Midwest (probably prompted by recent reading). There are many things in the Midwest that I miss, and one of them is the deciduous forest with its many kinds of flowers in the understory; there are well over a dozen species. It’s a spectacular show in early spring (when my grad students and I did research on seven of them), and other species come along later on.

Many of these early species take advantage of the open canopy that lets in plenty of light before the trees leaf out. The light is used to make carbohydrates for energy (needed for growth and seed development) and a bit of warmth facilitates the activity of insect pollinators. Even the species that don’t flower until later in the season can build up stores of energy to be used at their proper time. I think that the availability of light is probably one of several factors contributing to the floral diversity in the deciduous forest.

All that made me think about our coastal rainforest, whose floor is mostly shades of green, lovely in its own way but scarcely as showy. Here in the coastal coniferous forest, the understory is always dark; the canopy blocks lots of light all year long. And only a few flowers thrive throughout the forest; several others are happier in somewhat brighter places on the forest edges or in canopy openings, although they are sometimes found scattered within the forest.

Whatever the reasons for the dearth of understory flowers here, I chose to contemplate the flowers that regularly decorate the forest floor. They are little points of delight, good to envision on dark day even though their blooming time is still months away.

Bunchberry flowers. Photo by Bob Armstrong

–bunchberry or dwarf dogwood: very widespread in the forest, the four white bracts around a central cluster of small flowers make a good showing. The flowers release pollen in an unusual way: by a special catapult mechanism that throws the pollen up several centimeters. The flowers open elastically, explosively, and extremely rapidly (in less than a millisecond), flipping the pollen-bearing anthers upwards. Flowers may open spontaneously, tossing pollen up into the breezes, or when triggered by the visit of a large insect such as a bee, tossing pollen onto the insect’s body to be carried to another flower. Later on, the clump of red berries is equally showy. The leaves are typically evergreen, but sometimes turn red.

Rattlesnake plantain flowers. Photo by Bob Armstrong

–rattlesnake plantain: an orchid that has nothing to do with snakes or plantains, whose evergreen leaves are sometimes mottled with dark blotches. It produces a spike of white flowers that may be bumblebee-pollinated but are reported to be more often visited by moths in our area. Like all orchids, it depends on mycorrhizal connections with other plants for seed germination and early seedling growth; this mutualism may also supplement the nutrition of adult plants. This orchid can spread vegetatively by rhizomes (underground stems), and we often see patches of it with many nonflowering stems.

Fern-leaf goldthread, male flowers. Photo by Bob Armstrong

–fern-leaf goldthread: the flowers are small and delicate, often male, but sometimes hermaphroditic (both male and female). An individual plant can be change sex expression from year to year; if it produces energy-expensive seeds in one year, it is likely to be male or non-flowering the next year. Later in the season, fruiting plants make an interesting whorl of seed capsules that fling out the seeds when jostled. The leaves are evergreen. Although it is found in dense forest, survival of young plants is better where the shade is less dense. The flowers are pollinated by small flies, such as dance flies.

Single delight. Photo by Bob Armstrong

–single delight or shy maiden: An evergreen member of the wintergreen family, its white flower faces downward until it is pollinated, when the flower raises its face upward, exposing the seed capsule with the tiny seeds to the breezes. The flower is buzz-pollinated by pollen-collecting bumblebees, which vibrate the anthers to release pollen onto the foraging bees.

Western coralroot. Photo by Bob Armstrong

–western coralroot: Spikes of pinkish flowers on pink stems usually appear in groups. There is no green pigment at all and no capacity for photosynthesis; these plants are indirectly parasitic on trees and shrubs, via mycorrhizal fungal connections, and also may be saprophytic (feeding on decayed organic matter). The flowers are visited by bees.

Those species all grow under dense coniferous canopy and are seldom seen outside the dark forest. It seems likely that they are able to inhabit the deep shade because they are evergreen and therefore capable of photosynthesis at any time of year if it’s warm enough, or dependent on other sources of energy. All can spread vegetatively to some degree, by means of rhizomes, and probably all of them form mycorrhizal associations with other plants. At least some of them, including rattlesnake plantain, seem to flower infrequently, suggesting that energy resources may be limited. Self-pollination may occur in some of them, with or without an insect visitation.

One other species is often considered to thrive in dense, moist forest in western North America: three-leaf foamflower. Unlike the previous species, foamflower is not evergreen; it reportedly does somewhat better under less dense canopies and is also seen along trails in more open areas. It would interesting to know how it manages in the deep forest. Other species are sometimes found in the forest, but usually in more open parts of the woods or on the edges: examples include starflower, calypso orchids, three-leaf goldthread, twinflower, two species of twisted-stalk, and violets.

Whether bona-fide deep-forest denizens or dwellers on the fringes, they all provide visual delights, sometimes olfactory treats (twinflower, maybe rattlesnake plantain), and interesting natural history.

January bricolage

A stalking goshawk, some prime tracking, and a trip into a sub-nivean ice tunnel

Back in mid-January, during all that unseasonably warm and dreary weather, I looked out my front window one afternoon, to check on the twenty or so mallards that were congregating on the nearly ice-free pond. An adult male goshawk paraded along the bank, looking meaningfully at the ducks. The wary ducks had retreated to the center of the pond, where they waited to see what the predator would do. Perhaps they felt safer on the water than in the air. Darkness fell before I could observe the end of the stand-off.

In a recent essay I was moaning about that dismal weather that seemed to last forever, and I was looking for something cheerful to think about. But—wonder of wonders—a few days after I wrote that essay, a big moon appeared in the night sky and a bright yellow orb peeped over the mountains and the sky was blue instead of gray. Moreover, there was a nice blanket of new snow that added to the welcome brightness. Hurray!

Just before the sun really decided to reappear, we made a tour of the lower loop at Eaglecrest, finding the best assemblage of critter tracks we’d seen for a long time. A few hares had been out and about, and a weasel had bounded across the trail and into the brush in several places. Squirrels had made their usual highways out from the bases of trees. A mouse (probably) had ventured cross a small opening between two brushy shelters. Another set of obscured tracks were a puzzlement: I wanted them to belong to a marten. There were deer tracks in several places, including those of a very small one. The best finding was the wandering track way of a grouse (or ptarmigan), maybe searching for fallen seeds of for buds to nip and eventually disappearing into a thicket.

On a day of full sun (!!), we visited a meadow out the road, plonking about on snowshoes in search of whatever might be interesting. The snow was too crusty for shrews to leave their delicate traceries and voles were staying under the snow, but weasels had been exploring. A deer had come into the meadow and circled several small spruces, pausing here and there. It looked like lichens were on the menu, one kind in particular. Where the deer had been foraging, the spruces still held loads of Usnea longissima (old man’s beard) but little or no Alectoria (witch’s hair). But in parts of the meadow not recently visited by this deer, we could find draperies of Alectoria on the low branches. On other forays, I’ve seen neat browse lines along the edge of the woods, where all the Alectoria had been eaten. Now I have to wonder what makes that lichen a preferred food (at least at times).

One morning I headed out for a sunny walk on the west-side beach of Mendenhall Lake. Up at my mailbox I heard a ruckus in one of the trees overhead. There was a tight little ball of about four chickadees, fluttering and flapping and chattering, as they all tumbled from one branch to another. The fight continued down the slope and out of sight. One more thing to wonder about; this was more than a quick argument over a seed or two. Were they picking on an intruding stranger? Or had one of them seriously misbehaved in some socially unacceptable way? Or??

On another nice day, my foray took me to another meadow where the tussocks were separated by narrow channels that had been full of water; a layer of ice had formed on the surface. But the channels had dried up, leaving an air-space about a foot deep between the persistent ice and the bottoms of the channels. The snow cover made it hard to tell where the little channels were, so when a snowshoe found one and broke the ice, I dropped down catastrophically and pitched over in a heap. My ‘feet’ were twenty-five inches long and tangled unmercifully in the remaining ice layer as I tried to extricate myself, so it took a while for me to heave myself up on something solid. Eventually, I wearied of more falls and many near-misses and decided to bail out by walking under some big spruces, where there were no tussocks and empty channels to contend with. These lovely spruces were open-grown, so they had many long, low, sweeping branches for me to clamber over and under, making sure my big ‘feet’ didn’t get snagged. This was hard work too, but there was a little surprise: many of those long, low branches were decorated with a series of small mounds of cone scales, a few inches apart, as the squirrel had chosen a different spot on the branch for each spruce cone on which it snacked, rather than peeling off the scales into one big midden.