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.

Shorebirds

creative nesting strategies and social systems

Eleven species of shorebirds may nest in Southeast, according to Armstrong’s Guide to the Birds of Alaska. At least six of those are known to nest in the Juneau area. One additional species, the least sandpiper, was formerly relatively common near the airport dike trail and on the glacier forelands, but increased dog and human activity, plus habitat changes in those areas, have greatly reduced and perhaps eliminated this species as a local nester.

The term ‘shorebird’ reflects the fact that most people see them in winter and on migration, when these birds typically forage on shorelines. The Mendenhall wetland, for example, is recognized as a globally important stopover site for lots of migrating shorebirds. In fact, however, many shorebirds do not nest near shores. Instead, they commonly nest on tundra, in alpine zones, in forest, grassland, and muskegs.

I encounter spotted sandpipers most frequently, because they nest near rivers, lakes, or saltwater, on beaches and gravel bars. I see nesting semipalmated plovers in the tern colony near the glacier and also along marine shores. Killdeer try to nest in gravel pits, on flat rooftops, and at the edges of parking lots where the eggs are at risk of getting crushed. When I venture into muskegs in the nesting season, greater yellowlegs are hard to ignore, because they usually shriek and swoop and dive-bomb any intruder. I almost never see nesting Wilson’s snipe, but I hear them doing their aerial display high over their wet grassy or sedgy meadows—it’s called ‘winnowing’, from the sound made by air whooshing through their spread tail feathers. And nesting solitary sandpipers in their wooded wetlands I virtually never see; apparently few other folks see them either, to judge from the little research that’s been done on them.

Shorebirds are generally ground-nesters, but the solitary sandpiper is a notable exception. This species has the peculiar habit of nesting in the abandoned nests of songbirds such as robins, jays, and blackbirds. It is the only shorebird in North America to do so, and one of only two species in the world with this habit. After claiming a nest, the pair may make slight renovations to the basic structure. I wonder if they ever take over a newly built nest, driving away the owners! A pair of solitary sandpipers was known to nest this year in a flooded, shrubby area near the glacier, although we never found the nest itself.

solitary-sandpiper-by-bob-armstrong
Solitary sandpiper. Photo by Bob Armstrong

After I contemplated this strange habit for while, I realized that using an old songbird nest might be a great strategy. Predators (and bird-watchers) often find songbird nests by watching adult birds go to and fro, carrying nesting material or feeding chicks. Solitary sandpipers, however, don’t carry nesting material or feed their chicks. The chicks are precocial—hatched covered with fluffy down, eyes wide open, and able to run or swim almost immediately. So many of the usual cues for nest-finding are absent. But that leaves the question of how this nifty trick got started…

In general, our locally nesting shorebirds lay three or four eggs, but patterns of parental care vary considerably. Most of these species are socially monogamous (one female paired with one male, although copulation is not necessarily restricted to the mated pair), but some engage in degrees of extra-curricular activity, by mating with the neighbors as well. Both males and females can incubate eggs, apparently, except in Wilson’s snipe; in this species only the female sits on the eggs, and she does so for three to four weeks. During that time, the males are busily seeking extra-pair copulations. Male snipe make up for their lack of egg-tending, so to speak, by caring for some of the chicks (of which he may or may not be the father, because all his neighbors were as busy as he was). Snipe are unusual among shorebirds in that the parents actively feed their chicks for several weeks, and don’t just lead their chicks to food as the other species do.

Spotted sandpipers are exceptional to the usual arrangement of social monogamy, because they are often polyandrous: one female pairs with two to four males, either simultaneously or sequentially. Females hold large territories that include the smaller territories of her males. Males do most of the parental care, including incubation, but females may help at her first nest (until she gets another male) and at the nest of her last male of the season. Females even beat up their mates, sometimes, if the males are neglecting their incubation duties. Competition is fierce among females for males, and among females if certain females are perceived as especially desirable.