Ducks, sundews, yellowlegs, and…

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.

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.

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Beetle-mania

There are many more species of fish (about twenty-eight thousand species) than of any other kind of vertebrate (amphibians, reptiles, birds, and mammals). And there are about thirty thousand species of orchid, in a single taxonomic family. But those seemingly impressive numbers fade into the background in comparison to beetles.

Numbering well over three hundred fifty thousand (and counting), there’s a species of beetle for every ecological job—predators and parasites, herbivores and detritivores, scavengers and pollinators. They range in size from a giant six or eight inches long down to a wee thing only a fraction of a millimeter in length. Beetles have been around for a long time. Their fossil history begins before that of bees and ants and long before that of butterflies. Beetles appeared at least two hundred thirty million years ago, already diversified in their ecologies. Their diversity got a boost from the appearance of conifers, and then again from the arrival of the flowering plants, as they began to exploit these new resources. In fact, they were probably the first insects to pollinate the early flowering plants, since there were no bees or butterflies yet.

The phenomenal diversity of beetles is impossible to capture in a short essay. So let’s reduce the problem (slightly) by considering selected taxonomic families: the weevils or snout beetles (Curculionidae) and the rove beetles (Staphylinidae). These two families are probably the largest, in terms of the numbers of species. And I can’t altogether leave out three other interesting, large families…

Consider first the weevils, with over eighty thousand species, according to some taxonomists. Most weevils feed on the flowers and leaves of flowering plants (which now number hundreds of thousands of species). With that long snout, they bite and chew the plant tissues. The most notorious species is perhaps the boll weevil, which feeds on flower buds and fruit of cotton and ravaged U.S. cotton crops in the 1900s. A few weevils are aquatic, including some that feed on native and introduced water milfoil. One acts like a dung beetle, collecting the dung of Australian wallabies for raising their larvae.

One branch of the weevil family includes the bark and ambrosia beetles, which can wreak havoc in conifer forests. There’s a variety of ambrosia beetles, whose adults and larvae feed on ambrosia fungi that grow on wood. Some of these beetles even carry bits of the fungus in special pockets, and so they inoculate new tunnels under the tree bark.

The rove beetles number at least sixty thousand species, with vast numbers still uncatalogued by taxonomists. Most of them are small and inconspicuous, often living in leaf litter, under loose bark, in caves, and other places that are usually beneath our notice, scavenging whatever they can find. Some feed on carrion, a few are external parasites on fly larvae, some feed on fungal spores, and some burrow in shoreline sand to feed on algae and diatoms. Here in Southeast, one species of rove beetle is the chief pollinator of western skunk cabbage.

Rove beetles on skunk cabbage. Photo by Bob Armstrong

Rove beetles mating. Photo by Bob Armstrong

Many rove beetles are predaceous, often on mites, round worms, and fly larvae. For example, some species hang out in the dung of ungulates (deer, cattle etc.) and eat fly larvae while others maim and eat adult scarab beetles. Some species are specialized to live in the nests of birds, rodents, and even gopher tortoises, where they prey on the larvae of fleas and flies. One type of rove beetle has a very specialized and obligate relationship with neotropical figs, which are pollinated by specialized wasps, whose larvae grow up inside the fig. Inside the fig, the beetle adults and larvae feed on the pollinating wasps.

Many species of rove beetle live in the colonies of termites, ants, bees; one even inhabits the nests of a communally nesting butterfly in Central America. They are ‘inquilines’ or tenants in the host nests. Although some of them just scavenge in the middens of the ants and termites, others are predators, parasites, or kleptoparasites (stealing the food of the hosts); these species are well disguised, so that the hosts do not eject or kill them. They actually smell like their hosts, and in some cases they also look like them. Some rove beetle tenants secrete substances that calm the worker ants or even entice the workers to retrieve tenants that wander too far away. The rove beetles that live in certain termite colonies have huge glands that secrete drops that the termites love to eat. Some tenants are even treated as members of the colony, fed and protected as if they really belonged; in fact, these tenant beetles sometimes tap on the mouthparts of the host ants to elicit a feeding.

Two other large taxa are somewhat related to the weevils: The leaf beetles (Chrysomelidae), with at least thirty-eight thousand and perhaps as many as fifty thousand species, feed on plant material in a variety of ways, including leaf mining. The longhorn beetles (Cerambycidae), with maybe thirty-five thousand species, are plant-feeders too; the larvae dig into wood or mine the nutritious under-bark.

I can’t omit the so-called ground beetles (Carabidae), with over forty thousand species. Many of them are ground predators, but some eat seeds, some are inquilines in ant nests, some feed on slime molds, and some have parasitic larvae. Some eat snails by sticking the long snout into the snail shell and pulling out the resident snail. The well-known tiger beetles are thought to be the fastest running insects, chasing down their prey out in the open. One species is so quick that it can catch springtails in mid-jump. This family includes the famous bombardier beetles, which spray hot and caustic secretions at any attackers.

That’s just a sketchy introduction to some of the diversity of beetles. Beetle taxonomists and other researchers spend lifetimes immersed in the relationships and ecological stories about beetles. There is always more to learn and some of that will be surprising.