Ducks, sundews, yellowlegs, and…

dragonflies, gentians, leaf beetles, and a yellowlegs encounter too

On a hot, sunny day, I sat with some friends on a big log, looking across Berners Bay toward Lion’s Head. The tide was out, exposing some big rocks off to one side. A female merganser with four half-grown ducklings cruised around, eventually disappearing behind one of those rocks. Suddenly two of the young ones came hurriedly splashing around to the near side of the rock. Hmmm, something was clearly awry! They then went behind the rock again but soon reappeared, with at least one of their siblings, on one end of the rock. There they all settled down into what a friend once called “a little pile of cuteness”. What caused the commotion and the retreat to the top of the rock? We blamed a seal, whose head surfaced next to the rock, looking intently where the duck family had been.

What about the female merganser? As she drifted between her resting brood and the shore, an eagle swooped down on her from behind. A narrow miss for the eagle, as the duck quickly dove down. An exciting day for the duck family.

We were staying in the Cowee Meadow cabin and found entertainment on our doorstep. A red-breasted sapsucker regularly visited the logs of the cabin walls, peering around at us on the deck, almost as if it were hoping for handouts. Later, a sapsucker went down to the ground by the fire-pit and picked up several woodchips, filling its bill and taking off with them. Why would a woodpecker scavenge chips when it could make its own, and what did it want with them, anyhow?

The front of the cabin was patrolled by a large dragonfly that flew back and forth between the creek on one side and the nearby trees on the other. A sudden flash of blue emerged from the trees and made a grab for the dragon, but I think the jay missed its mark; soon thereafter a large dragon was again patrolling the front of the cabin.

A few days later, still in the hot sun, Parks and Rec went to up to Cropley Lake. Great expanses of meadow were spangled with thousands of small white stars: swamp gentians. This annual plant is probably pollinated by flies (rather than bees), but there has been very little study.

bog-gentian-by-bob-armstrong
Swamp gentian. Photo by Bob Armstrong

A little lower down in the meadow vegetation, we found many tiny, white, five-petalled flowers of the round-leaf sundew. These small insectivorous plants were so common in some areas that they almost made a carpet, although not all were flowering. Experimental studies, comparing sundew plants with lots of captured insects to those with few captures, revealed that well-fed sundews grow better and make more flowers. The flowers have no nectaries, so they have little reward for pollinators; they are capable of self-pollination. However, insects, mostly flies, do visit the flowers at times. So flies can be pollinators but they are also prey for this plant. That seems self-defeating! However, they are likely to be different kinds of flies, as shown for the closely related long-leaf sundew.

On a walk out toward Nugget Falls one morning, I noticed that the cottonwood leaves had been severely damaged. So of course I looked more closely, and I found lots of small black larvae of leaf beetles. They had munched up the surface layers of both top and underside of the leaves, leaving nothing but a delicate network of leaf veins. Adults of these leaf beetles overwinter in the leaf litter and lay bunches of eggs in spring. The larvae pass through several molts as they munch and grow; the early stages (called instars) are often colonial, feeding in gangs; later instars are more independent. Some trees had been much harder hit by these beetles than others, but is that because some trees are just more susceptible, less well protected, or because of chance events when female beetles were laying their eggs?

A friend and I walked up to a meadow on the Spaulding trail to see if the long-leaf sundews were flowering yet. No, but we had an exciting time nevertheless. There were fair-sized shorebird footprints in the mud of the drying ponds and a shorebird was calling persistently from the top of a dead pine. As we turned to go, we got dive-bombed from behind—a close pass ruffled my hair. Then a second attack, accompanied, as before, by loud cries. (OK, OK, we are leaving anyhow…). Those greater yellowlegs were clearly defending something important, and at last we saw it (there might have been more, somewhere)—a big, tall chick, still fuzzy and flightless, sneaking through the sedges. So we went quietly on our way, leaving them in peace.

A group of five mallards in female plumage come to my home pond that same day. They foraged all around the edge, nibbling here and there. Then they went over to the bank on the far side and I expected them to climb up and settle down for a nap, which is what usually happens. But this time, the naps were delayed and the birds were almost hidden in the brush. The blueberry bushes started twitching and jumping, and I could see that the birds were reaching up to !!pick blueberries!! They cleaned out the berries on those bushes and finally settled in for a nap. I wonder how they learned that blueberries make fine snacks—so different from their usual fare.

Winter wanderings

In early January, the ice on the ponds in the Dredge Lake area was good and solid, although there were isolated spots of open water where upwellings slowed the formation of ice. I traipsed around some of the trails and ponds, finding tracks of shrews, hares, and a mouse. Otters had slid over a beaver dam and then up a frozen slough, no doubt hoping to find a fish or two.

One day in mid-January, a friend and I explored a frozen pond, walking on snowshoes to spread out our weight, in case of a spot of weak ice. A little snow was falling, so it was a beautiful walk.

Beavers had made a small food cache near their lodge, including some hemlock branches. There were lots of spider webs and long, trailing silk threads used by airborne spiders. We wondered if any critters, in addition to some spiders, eat that silk to recycle the protein.

Around the bases of several trees at the edge of the pond, we noted the tracks of a small bird, probably a junco. It had apparently inspected each tree base quite closely, possibly picking insects from the spider webs that curtaining the gaps between the upper roots or searching for stray seeds.

A vole had crept out of one bank of a frozen rivulet, crossed he ice, and scuttled back to where it came from. My companion had observed such behavior in other places when the animal was seen to be a red-backed vole, so we assigned that perpetrator to those tracks. Deer tracks crisscrossed the pond ice, and deer had been feeding on the witches’ hair lichens that grew on small trees at the pond edge. My sharp-eared companion heard a brown creeper, which we soon saw as it hitched its way up a spruce trunk.

Many of the alders in this area had neither cones from last summer nor any male catkins for next spring. This was unlike other alder stands we’d seen, so we wondered why this stand was evidently reproducing very poorly. Perhaps the high level of water in the pond was too much for them.

We also noticed that here and in some other places the alders had retained many of their dried and shriveled leaves, instead of letting them drop to the ground. Blueberry shrubs sometimes do this too. In other regions, oaks, beeches, and other trees also retain many of their dead leaves throughout the winter. The term for retention of withered old flowers or leaves is ‘marcescence’. Marcescent leaves have attracted a good deal of speculation about why these plants do this, such as deterring deer and moose browsing, trapping snow for release of moisture in spring, or delaying decomposition until spring, when nutrients are most needed for growth. However, apparently very little investigation has explored those ideas. In some cases, particularly when marcescence is occasional and not regular, the retention of dead leaves may just happen incidentally because the weather suddenly changed in a way that prevented the usual mechanism of leaf-drop (formation of the cut-off or abscission layer at the base of the leaf).

A few days later, along the Auke Lake trail, (and later in other places) we noticed that many of the blueberry bushes had small galls on the twigs, often at the bases of marcescent leaves. The galls are really quite small, and I have to wonder how many times I have walked past them without noticing. They do seem to be more conspicuous against a snowy background…Some blueberry galls are made by midges or wasps, but these did not fit the descriptions of such galls, so the makers of these galls remain to be determined.

Toward the end of January, I went with a friend on the Pt. Bridget trail. Near the trailhead, we found a place where a weasel (I think) had fossicked about in the mud at the bottom of a hole in the snow, and come up to leave a string of its small, muddy footprints on the snow, before diving back down under the deep snow in a new spot. Somewhat to my surprise, the lower branch of the trail, along the edge of the big beaver meadow, was quite passable, provided one didn’t mind a couple of inches of water here and there. A moose had used the trail too, taking advantage of a deeply trenched part of the path—and a small wooden bridge—to avoid some of the post-holing that was required in the rest of the meadow. The bible-camp horses had left ample evidence of time spent on this side of Cowee Creek, on the beach fringe as well as in sheltered places under the conifers. Pawing away the snow and stirring the long, dead grasses, they also had clearly been looking for precocious green shoots under the snow…and had found a few.

As we left the area near the cabin, my companion spotted an owl, probably a short-eared owl, as it swooped down to some bare ground next to a tidal slough (the tide was out). It was probably trying to catch an unwary rodent, but we could not be sure it was successful. It soon flew up into the nearby trees, changed perches, and eventually took off across the wide meadows, screened from clear view by tall spruces.

A day or two later, when Plan A for a beach-walk was foiled by ferocious north winds on Lynn Canal, another friend and I eventually found a sheltered beach near Amalga Harbor. Moving slowly and quietly, we managed to share the beach with a trio of common mergansers that paddled slowly along the tide line. Then they all hauled out and snuggled up in a close-packed row to sun themselves.

I have learned a new word for verbal bric a brac like that found in this essay: bricolage. ‘Tis a very useful word for assortments of diverse things brought together in some more or less unifying way. There may be more bricolages here in the future.

Winter wildlife extravaganza

in Juneau’s Auke Bay

During late November and early December, 2015, Auke Bay harbor put on a wildlife spectacular, drawing photographers, reporters, and just plain gawkers (such as me). Hordes of young-of-the-year herring, mixed with a few capelin and sand lance, milled around the docks and boats. The banquet of small fish also drew many predators, who put on a good show for observers.

Why are there so many young herring in the harbor this year? There are possibly several reasons, suggests Michelle Ridgway (Oceanus Alaska). It may have been a good spawning season in spring. The sunny spring, plus an El Niño, warmed the harbor waters, even at considerable depths, and all the spring run-off from the soggy land brought in nutrients. Those conditions produced a fine bloom of phytoplankton, which led to good body condition and burgeoning populations of zooplankton. For example, Ridgway has noticed extended reproduction of little shrimp-like crustaceans called mysids, extra-large fat globules in copepods, an abundance of amphipods not far from the surface, and an unusual influx of ‘sea butterflies’ (molluscs that fly through the water). That made excellent foraging for baby herring. In addition, young herring may seek protection from the massive maws of humpback whales by moving into shallower bays and harbors, with docks and boats, where the whales are less likely to forage intensively.

Herring and other so-called forage fishes often form densely packed balls, especially when predators are lurking about. When a predator dives through the ball of fish, the survivors scatter in all directions, but not far and only briefly, before returning to the tight cluster. Researches have called this behavior ‘the geometry of the selfish herd’: each fish trying to put as many other little fish as possible between itself and predators. The result is a tight ball of nervous, jittery fish.

The baby herring in the harbor had every reason to be jittery. The millions of small fish were being attacked on all sides by throngs of predators. They may have eluded most of the whales in the confines of the harbor, but other predators took advantage of the great aggregation.

A gang of Steller’s sea lions cruised rapidly back and forth, diving continually, probably after pollock that were gorging on the herring. The pollock drove the little fish toward the surface. The sea gulls knew this, of course, and hung about, just waiting for the fleeing fish to get close to the surface where the gulls could nab them. Indeed, the fish were caught ‘between the devil and the deep’ (the gulls and the aquatic predators respectively).

Several harbor seals were there, some with well-grown pups. They did their share of fish-driving too, but usually not near the sea lions. I watched one seal surface-swimming slowly along, on its back, in a most relaxed fashion. It may have been looking down into the depths, for eventually its head went down, followed by the plump body, into a mob of fish.

Scattered Pacific loons and little clusters of common mergansers foraged away from the biggest crowds of predators. Marbled murrelets in snazzy winter plumage could be observed at close range; they were much less skittish than in the breeding season.

The most amazing sight was the huge flock of common murres—many hundreds of them. They rafted up just beyond the last float and split off occasional smaller bunches that moved in among the inner floats. They, and everybody else except the gulls, avoided the sea lions that charged to and fro. I had never seen so many murres before, except at the St Lazaria nesting colony on the outer coast. The murres talked to each other constantly, except when they were diving.

murres-in-Auke-Bay-Jos
Photo by Jos Bakker

That huge concentration of murres was arguably the most unusual happening in the harbor. All the other predators visit the area rather regularly to feast on small fish that spend the winter there. Although murres nest on the outer coast, they tend to move closer to shore in winter, congregating where prey is abundant. But we don’t customarily see the murres in such numbers in Auke Bay harbor. Furthermore, over near Glacier Bay, good observers reported uncountably huge numbers of murres moving about.

The throngs of murres may be a sign of bad news, however, according to John Moran (NOAA). A mysterious oceanic anomaly in the Gulf of Alaska called the Warm Blob (because water temperatures are as much as five degrees (F) above average) created nutrient-poor conditions that greatly reduced productivity and thus decreased the abundance of fishes that feed on plankton, or at least caused them to move to deeper waters where diving birds can’t get them. The Blob developed in 2013 and its effects have contributed to reduced nesting success and great mortality of some marine birds in the Gulf. The poor food supply may have been one factor that drove the murres we’ve seen in Auke Bay out of their usual foraging areas in search of better feeding conditions.

All those baby herring in the harbor seem to offer a ready banquet but, in fact, those little fellows have very little fat because they put their energy into growing as fast as they can. On a gram-for-gram basis, they are much less rewarding than capelin or adult herring, for example, and even less than krill, according to data of Moran and colleagues. So a murre or any other predator would need a lot of them in order to survive—and that’s certainly what was available in the harbor.

Humpback whales were reported to pass by the harbor upon occasion, but there are other spots where they might find better foraging. Seymour Canal is a good place for foraging on krill, for example, and adult herring (far more nutritious than the young ones) from all over Lynn Canal winter in deep, dense schools northward of Tee Harbor. When a whale dives deep through such a school of herring, some of the fish try to escape up shallower water, but there the sea lions can get them. Sea lions themselves may attract the attention of transient killer whales; a few years ago, Moran watched killer whales take down five sea lions (plus two probable kills) in five days. But in Auke Bay harbor, the foraging sea lions were quite safe from the killers.

Eagles were notably scarce in Auke Bay harbor during this extravaganza, although they are known to feed on murres (we saw the evidence in Berners Bay one spring). Perhaps the eagles sought out the adult herring to the north.

A little squad of goldeneye ducks quietly kept to themselves along a rocky shore of the harbor. Seemingly uninterested in the shimmering mass of herring, they may have been looking for molluscs.

Thanks to John Moran of the NOAA lab and Michelle Ridgway of Oceanus Alaska for extensive discussion, not all of which could be packed into this essay.