September

delights of a season of slowdown

In September, the natural world slows down. The days get shorter and shorter, bird song diminishes to next to nothing, marmots are hibernating and the bears soon will be. Most of the wildflowers are done blooming, although a walk above the tram in the middle of the month revealed the last few flowers of six species. And the alpine zone is where we find our best fall colors: various shades of red on dwarf dogwood, avens, and lowbush blueberries, gold and russet on deer cabbage.

Nevertheless, on one day in mid-September, I enjoyed sightings of two kinds of critters that I don’t see very often.

Rusty-Blackbirds-by-bob-armstrong
Photo by Bob Armstrong

There were three rusty blackbirds on the shore of Mendenhall Lake, foraging over the wet sand and in the shallows. Rusties breed all across the boreal forest of North America and winter chiefly in the southeastern states. Even though Southeast Alaska is hardly on a direct route to the usual wintering area, I see them during the spring and fall migration seasons, sometimes by the ponds in the Dredge Lake area, occasionally elsewhere, but always in small numbers. Sadly, those numbers are likely to get even smaller: the number of rusty blackbirds has dropped dramatically in recent years, probably for several (undetermined) reasons.

Rusty blackbirds in Alaska often nest in wetlands and near ponds in dense, small black spruces, where nesting success is good, or in willow shrubs, with less success. Unlike their marsh-nesting relatives (such as red-winged blackbirds), they are usually monogamous. But similar to the other blackbirds, females do the tasks of incubating eggs and brooding young chicks. Blackbird males pitch in to help feed the chicks (but polygamous males commonly help mostly at the nest of a primary female; secondary females get less help).

In the nesting season, rusty blackbirds feed mostly on aquatic insects, including dragon and damselflies. During the rest of the year, the diet also includes seeds of many kinds and fruit. I was fascinated to learn that rusties sometimes kill and eat other birds.

The other critter I don’t see very often was Milbert’s tortoiseshell, a beautiful butterfly whose deep brown wings are banded with orange and yellow and adorned with red spots on the leading edge. All the color is on the dorsal surface, visible when the wings are spread. The ventral surface of the wings, visible on the folded wings, is more camouflaged, looking perhaps like dead leaves or bark. The one I saw was foraging on yarrow flowers—the only flower still in bloom in that area.

This butterfly overwinters as an adult, tucking into crevices in houses or trees, and emerging again in early spring. Batches of eggs are laid on nettles, which are the chief food of the caterpillars. (We could use more of them on the lower reaches of the Granite Basin trail!) Young caterpillars often forage in groups, but older ones are more solitary. They pupate in a folded leaf. When they metamorphose to the adult stage, they forage on nectar of many flowers, as well as sap and rotting fruit. In parts of North America, there may be two broods of caterpillars each year, but I doubt that there is more than one per year in Alaska. The one I saw was surely getting ready to hibernate, filling up the tanks, as it were, to last through the winter.

Addendum: As I strolled down to the beach below the pavilion near the visitor center, I stopped to watch the bear called Nicky and her little cubs. They trotted along the lowest pond on Steep Creek, where a few coho were jumping, waiting for enough water to allow them to ascend the creek. I don’t get to see Nicky very often either, so this was a happy sighting. The cubs looked pretty healthy but still very small…they will need their mom to catch some of those coho, so they can get fat enough to last the winter. But even Nicky, an expert fisher, can’t catch very many until there is enough rain to raise the water levels so the fish can get up into the stream itself. I have to hope for rain!

Beavers

the many benefits of an underappreciated mammal

beaver-towing-branch-jos
Photo by Jos Bakker

North American beavers were very nearly exterminated from the entire continent by European trappers and settlers. The near-absence of beavers for over 200 years changed the face of the landscape dramatically, not necessarily for the better. As humans took over the landscape and modified it to suit their real or imagined needs, they generally treated the few remaining beavers as intruders into the human domain, to be eliminated one way or another. That attitude still prevails.

To give local examples from my experience: one fellow said he hated beavers because one beaver chewed on a tree in his yard (serious profiling! Not politically correct). And a woman shrieked maledictions upon me, saying that beavers should be killed because they kill trees. DOT worries if pond levels rise along a roadbed or under-road culverts are clogged. Walkers complain if trails are flooded. And so it goes. For some reason, the usual first level of response is KILL them!

But although beavers so often get a bad rap, they are not all bad. In fact, they do some very good work. For instance, in the western Lower Forty-eight states, their dams help reduce erosion, trap sediments, control floods, and raise the water table, resulting in better grazing for ranchers’ herds and better stream quality for fish. Recognizing this, agencies and ranchers have begun to re-introduce beavers in some areas, to the benefit of humans, as well as fish and wildlife.

People often assume that beaver dams block salmon from coming in to spawn, to the detriment of our fish runs. However, adult coho and sockeye can usually jump or slither over most small beaver dams, if there is enough water below the dam to let them gather momentum. Furthermore, the adults are fully capable of waiting for days and days, until rains raise the water levels enough for easy upstream passage. So the common assumption of blockage is often just that—an untested assumption.

Furthermore, scientific research has shown that the ponds formed by beaver dams are superb habitats for juvenile sockeye and coho salmon: they grow bigger and faster there than in other possible sites, so they go to sea in better shape and survive better, and therefore more of them can return as spawners. In fact, in many cases, the size of a run is limited by the amount of suitable rearing habitat for juveniles and juvenile survival. For this reason, fisheries biologists in the Pacific Northwest have reintroduced beavers to some stream drainages, to help restore the waning salmon runs.

Ecologists also observe that beaver ponds are good habitat for nesting ducks, some shorebirds and songbirds, moose, and amphibians. Migrating swans and geese use them regularly. Standing dead trees are used by woodpeckers, chickadees, and certain species of duck. All this research and observation strongly suggest that we humans should take a less simplistic, more multi-factorial approach to beavers and their activities, in fact, an ecosystem-level approach.

Land managers in agencies and private concerns are learning that it is often possible to manage the effects of beaver activity rather than reflexively killing the beavers. There are now beaver-management specialists who offer solutions to many perceived problems—finding ways to keep the benefits of beavers while ameliorating or eliminating the problems. Among the techniques they use are devices known as pond levelers of several designs, diversion dams, exclusion fences of various sorts, baffles to prevent culvert clogging, step pools to facilitate fish passage. Trails can be raised or re-routed. Sometimes all that is needed is making and maintaining notches in dams for water and fish passage while lowering water levels somewhat.

In short, it is often possible to balance the ‘bad’ with the good and find a win-win solution.

 

Early fall in Cowee Meadows

burying beetles, sweetgale ecology, and dragonfly sex

A trip to Cowee Meadows usually provides a curious naturalist with something to contemplate. It’s also a good idea to keep an eye out for large, brown, sometimes temperamental, mammals with claws or hooves.

A stroll out there in mid-August discovered several things of interest.

A desiccated toad carcass lay in the trail, cause of death unknown. The body was attended by two big, orange and black, sexton beetles, maybe just looking for a meaty snack but possibly foraging for a carcass on which to rear a brood of larvae. Sexton beetles are also called burying beetles; they bury the bodies of small mammals and birds (or chunks of dead salmon), denuding them of fur and feathers, which are used to line a chamber housing the carcass. Eggs are laid near the buried carcass and the larvae crawl into the food-filled chamber. Unusual among insects, both parents feed the larvae on liquefied, partially digested meat, as the larvae also feed for themselves on the stored carcass. The number of larvae feeding on a carcass may be regulated by parental infanticide; if there are too many for the available food pile, the parents reportedly reduce the numbers. If for some reason, a female beetle does not have an active partner, she can raise a brood by herself, fertilizing her eggs with stored sperm. In this case, the question in my head was whether or not a desiccated toad would make good larval meals.

The low wetland before the beach berm is thronged with aromatic sweetgale shrubs. They harbor symbiotic bacteria in the root system; the bacteria take atmospheric nitrogen and ‘fix’ it into a form that plants can use. This species usually (but not always) has male and female flowers on different individuals. Male plants have already set their flower buds for next year, while female plants bear cone-like structures with small one-seeds fruits attached to the core. Some small critter had feasted on the seeds of a few plants, leaving the cone-core and fragments in a heap. A fat green caterpillar grazed steadily along the edge of one leaf, not deterred by the reported insect-repellent properties of this species. I was interested to find out that two field guides and two tomes on the flora of Alaska do not instruct a field naturalist how to tell male from female flowers—but the Trees and Shrubs of Alaska by Viereck and Little does!

Out on the beach, it was time for tea and snacks on a favorite log. The tide was low, and far out on a distant rock there was a black lump, which turned out to be an oystercatcher, able to loaf now that the chicks have been raised.

Instead of hobbling over the cobbles around the point, the return trip came back through the grassy/sedgey meadow, where the trails of trampled vegetation left by wandering horses made easy walking in most places. Sparrows popped up out of the tall grass and quickly dove back into the next dense cover. Closer to the river, the vegetation is shorter and marsh felwort flowers began to show up, not only on gravelly soils (as the books say) but also in deep black muck.

The old trail next to the beaver pond has been abandoned, but the water level was very low; there was not even any water in the stream below the dam that makes the pond. That encouraged a little exploration at the edge of the wet meadow along the old trail, which was apparently built (or rebuilt?) without consideration of beaver activity. In recent years, beavers had raised the pond level so the trail was often flooded well over ankle-deep; water was often trapped between the log rails on the trail margins. Rows of young alders have now sprouted up along the edges of that trail, making most of it rather impassible. But the low water level made it quite easy to tromp through the sedges on a parallel route. The newer, improved trail along the hillside would still be the trail of choice most of the time.

Near the beaver pond, dragonflies zipped to and fro, some of them in copula. Male dragons (and damselflies) chase whatever female flies by. If a female is not interested, she may evade the male by running away or hiding; in some species she just plays dead! A successful male grabs a female behind her head with claspers at the end of his abdomen, and they may fly in tandem for a while. The female, if willing, bends her body under his to bring her genitalia (near the end of her abdomen) next to where he has previously stored his sperm in the anterior part of his abdomen, so sperm can be transferred. Copulating dragons make a circle or ‘wheel’ of their bodies. If the female had mated previously, the present male may try to scrape out the sperm of the first male; the ‘opinion’ of the female with respect to this action apparently has not been recorded.

Northern-Bluets-mating-by-bob-armstrong
Photo by Bob Armstrong

Some days later, I watched a pair of bluet damselflies in tandem, perched on a sedge blade in a mid-elevation muskeg pond. The female bent her body up to touch his, in the copulatory position, several times, but they did not form the mating wheel. Three other bluet males patrolled this pond, sometimes zooming in closely on the pair, and even contacting them, as if to try to steal the female away. This is a behavior I’d not seen before. At the edge of the pond lay a dead female, possibly drowned in the act of laying her eggs in underwater vegetation. Some bluets lay eggs in vegetation near or on the surface, but some species of bluet actually submerge the whole body while egg-laying, and upon occasion need to be pulled out by their partner or perhaps by a nearby unmated male.