Recent finds along the trail

eggs and erosion, flowers and porcupine nibbles

A stroll across Bridget Cove tide flats in early July brought us to a stand of eelgrass. To our surprise, the eelgrass was dotted with many thousands of fish eggs. We thought this was too late in the season for herring, but a forage-fish expert told me that herring have been known to spawn there in early July. The eggs would need to incubate for about two weeks (at a temperature of eight degrees centigrade) and the embryos of these eggs appeared to be in early stages of development. If we went back a week or so later, they probably would have hatched.

After the recent jökulhlaup, I went to inspect the ‘gooseneck’ area on the lower Mendenhall River, where a sweeping loop in the river has created a narrow peninsula just upstream from Vintage Park. I imagined that the big water coming down would have breached the really narrow part of the peninsula, flowing over the top and eroding at least an overflow channel. But no! There is indeed some new erosion of the bank on the upstream side. On top, trees now lean downstream, their roots tipping up and making large cracks in the soil; they will probably fall rather soon, reducing the top of the peninsula to just a couple of feet in width. Something to keep our eyes on!

Just on the other side of Cropley Lake, in a wet area, is a stand of pale yellow flowers. This is a species of fireweed called yellow fireweed or sometimes called yellow willowherb (Epilobium luteum). The familiar pink flowers of the usual fireweed (formerly a species of Epilobium but now reclassified in a separate genus, Chamaenerion) are evident all over town, but the yellow one is much rarer. We’ve seen small numbers of this in only a few places around here. It can propagate vegetatively, so once a plant gets established from seed, it can spread locally if the habitat is suitable. And by the way, why is the pollen of the pink fireweed sometimes blue-green?

Another familiar local plant is known as goatsbeard (Aruncus dioicus). This species is dioecious, bearing male and female flowers on different individuals. On a recent stroll up Perseverance Trail, we looked more closely at the narrow flowering tassels. Indeed, just as expected, males and females were distinguishable. However, we were interested to see that in a very few male plants, a small number of seed pods were developing on some of the tassels. I recall that some other reportedly dioecious plant species have similar transgender issues at least upon occasion. Because the female plants were well past flowering and had well-developed seed pods, we could not tell if any of them had once sported male parts.

On Gold Creek, a female harlequin duck was foraging, dipping and diving among the rocks. We enjoyed watching her skillful maneuvers, swimming upstream underwater, skittering rapidly on the surface of a broad, flat rapid, doing balanced skids on wet rocks, and ferrying across the fast chutes just like a kayaker or a canoeist would do. Humans may have learned this technique, long ago, from the ducks.

A friend reported a dipper nest in the spillway on Gold Creek, so I went to look. Sure enough, in a big crack in the concrete was a pile of moss with an opening through which I could see movement. Mama dipper was either incubating eggs or brooding chicks, while Papa was on guard on a boulder nearby. Later, I looked again, and now the adults were both outside, feeding three or four small, piping nestlings. Big loads of caddisfly larvae and other goodies went down the begging mouths. Very satisfying to observers, as well!

One day we walked on the sand flats of Eagle River along the Boy Scout Trail. There were small footprints in the sand, looking a bit like a baby’s foot but with five claw marks well ahead of the pad. Hmmmm, probably a porcupine. And presently we saw the perpetrator, busily nipping of the ends of beach greens (a.k.a. seabeach sandwort; Honkenya peploides) shoots. After some minutes, the critter bustled off toward the woods, and we went to look at the nibbled shoots. It had ignored the shoots with seed pods and seemed to have concentrated on the shoots with flowers.

This area of sand flats has many clumps of beach greens, whose shoots sprawl out in all directions. In one portion of this plant colony, most of the clumps had been rolled up from one side…the long shoots on that side were flopped over the ones on the other side, consistently in the same direction. We know from reports of other observers that porcupines sometimes roll up outdoor carpets and lick what is underneath. Could these plants reflect similar behavior? If so, what are the animals getting?

Thanks to Darcie Neff for information and references.

Streamsides in winter

some rewards of getting out and about

I take a walk on one of Juneau’s many trails almost every day, alone or with friends. Sometimes it’s a bit hard to get myself out the door, because there’s a deluge or big wind, or I’m just feeling lazy. So I remind myself that sitting inside my house practically guarantees that I won’t see much of interest—so get out there and look around, something may turn up. And something always does.

Here’s a sampling of small pleasures that turned up along Juneau streams in January:

–Fish Creek: Huge, thick plates of ice had washed far over low banks on the small, upstream floodplain and into the forest, and also into the meadows around the combat-fishing pond. It was fun to speculate what it would have been like to actually see the ice cakes pushed out of the creek and into the forest (from a safe distance, of course).

–Eagle River: A dipper was foraging along the edge of the river, occasionally disappearing under the ledges of ice that lined the shores. It searched diligently in the riffles and sometimes brought up something that required some work before swallowing—maybe extracting a caddisfly larva from its case.

–Mendenhall River: I checked out the ‘gooseneck’ peninsula where a breakthrough seems imminent. The narrow neck of land is thinner every time I look, and it seems as if one more good jökulhlaup might be enough to make an island of the peninsula tip. I have to guess that hydrologists have determined the large buildings just downstream to be safe from such events.

–Fish Creek: Winter-active beavers had dragged brush from recent cuttings over to their home pond, leaving trails in the old snow. These beavers, and others in Juneau, have obviously not read the books that report beavers holing up in their lodges for the winter.

–Mendenhall River: A pair of hooded mergansers, the snazzy, gorgeous male with a more-demurely -plumaged female, sailed sedately downstream. Hooded mergansers are the smallest of the mergansers; they eat a more varied diet that includes not only fish but also lots of invertebrates. Males and females commonly pair up in late fall and hang out together through the winter until nesting time in spring. Then the female choses a nesting cavity in a tree or nest box, usually not too far from water, lays her fertilized eggs, and incubates the clutch of eggs, while the male, having done his studly task, goes off and leaves her to do the work. When the eggs hatch, the tiny ducklings almost immediately jump out of the nest cavity, fluttering down to land with a little bounce, and follow mama to feeding areas. This species nests in some places in Southeast, but not commonly. In winter, it favors coastal waters such as shallow bays, estuaries, and tidal rivers, so we see it occasionally.

male-hooded-merganser-by-bob
Photo by Bob Armstrong

–Eagle River: Small insects were flying, possibly midges, looking rather like miniature mosquitoes. Some other insects, such as certain stoneflies, regularly fly in winter, but I’d like to know more about midges (if that’s what they were).

–Cowee Creek: A kingfisher winged upstream and perched over a pool. I hoped to see it catch a fish, but apparently it saw nothing worth pursuing. Kingfishers and many other birds have two small areas, called fovea, on the retina of the eye (humans have just one); foveas have a high density of visual cells and provide good acuity. One fovea, near the bill, is used for monocular, sideways vision; this fovea has especially numerous visual cells and is used for finding prey (as well as keeping track of other birds and predators). When a kingfisher dives and enters the water, its vision switches from that fovea to the other one, located away from the bill; using these lateral fovea in both eyes gives the kingfisher binocular vision and better depth perception as it gets close to an elusive small fish that may try to dart away. When the bird dives, its eyes are protected by a nictitating membrane. As some of us have found out when we try to grab something underwater, refraction often causes us to misjudge the depth of that object; kingfishers can avoid much of that problem by diving vertically after prey that is deeper than a couple of inches.

Kingfishers nest in burrows alongside or at least near streams. I have found nest burrows by several Juneau streams. The lower Mendenhall River and Cowee Creek, where it flows through the meadows, have cut steep mud banks that are perfect places for kingfisher nests. But there’s a problem: in both areas the streams are rapidly eroding those banks; what remains is still potentially suitable for nest burrows, but the stability of the banks is obviously uncertain, and high water in spring and summer could wipe out a kingfisher nest.

–Peterson Creek: A little light snow had fallen on top of old, crusty snow. Shrews had traveled far and wide over the top of the snow. One shrew had plunged, presumably deliberately, over a small mud cliff at the edge of the stream. A few feet downstream, its tracks continued on a flat shelf of shore-bound ice. It sure looked like the critter swam from the base of the cliff to the ice. There is a shrew that is adapted for swimming, but it is not as common here as ordinary shrews, which apparently can swim if necessary.

What did I get out of those little walks? Some really fresh air (Juneau is good for that!), mild exercise (followed by a comfy cup of tea), sometimes companionship, sometimes a solitary meditation, and some observations to think about. Not bad for a small investment.