Little stories on the trail

Out on the wetlands in late September, I spotted a raven carrying a fish up into the conifers at the edge of the meadows. After eating part of the fish, the raven picked up the bedraggled remains and flew out to a mossy stump, where it cached its prey in a crevice. Then it hopped up to the top of the stump and looked carefully around in all directions for several minutes. It saw another raven, perched a hundred yards away, and me with my binoculars, and forthwith decided to move its catch far, far away. Sharing was not an option.

In mid October, the coho were getting ready to spawn in Steep Creek. One of the bear-watchers favorite bears, a cinnamon female called Nicky for the nick in her left ear, appeared with her chubby black cub. An expert fisher-bear, she caught a coho almost immediately and retired to the brush on the bank to eat it. Little cub wanted some too, and complained repeatedly, but mama was not about to share; she growled and moved the carcass away from every approach her offspring made. When she finally finished and the two bears wandered on upstream, a watching magpie came down to look for scraps.

Nicky with a cub. Photo by Jos Bakker

About thirty minute later, upstream near the little waterfall, Nicky caught a second fish and carried it about forty yards away to eat it, calmly avoiding a cluster of people on the trail. Cubbie apparently managed to grab a chunk and eat all of it at some distance from mama. Nicky finished her catch, leaving only the dorsal fin. Then the little family moved on up the hill, leaving some very please bear-watchers behind.

The next day, she came through again, caught at least two coho, and added some northern ground cone to the meal. This time, she shared a little of the fish with the cub.

A little exploratory walk along Eagle River yielded several small mysteries. Invertebrates had left a variety of tracks in the mud. Worms, snails, slugs??—hard to know. But one long, thread-thin track ended at a tiny white spot less than a millimeter wide. My companion whipped out a hand lens to inspect the spot more closely and—oh my—it had a head end and it squirmed! This little maggot had travelled more than a foot, headed for who knows where. We released it to continue its trek.

Bears had been digging in many places, but the digs were several weeks old, so the tops of the dug-up plants had rotted beyond recognition. The remains of some of the dug-up roots had made new green shoots in preparation for next year, but slugs had eaten out many of them, leaving dry, brown bud sheaths behind. We were interested to find that the bear digs had exposed some inch-thick rhizomes (underground stems) that we traced back to lupine plants. This was the first we knew that lupines could spread in this way.

Strawberry plants are not common out there. But one, living dangerously at the edge of the overflow zone, had made an impressive runner, with the starts of about seven new plantlets at intervals. If they all survive the floods, there will be quite a family here.

On the bank of a slough, we noticed a few old bones poking out of the moss and mud. Looking more carefully, we eventually found several vertebrae, some ribs, and three leg bones. But whose?? A little forensic work made it likely that the bones had belonged to a long-dead bear.

Some other cool stuff: A flicker on the edge of a beach flew up into the nearby spruces; this seldom-seen woodpecker was probably on its way south. Some sedges with small, black spheres on the seed-head; they collapsed into dust at a touch and were probably the sporing bodies of a fungus. A Russula mushroom, whose broken, hollow stem revealed three dark, slender millipedes; what were they doing in there?

Every time we go out to find something of interest, we find at least two or three things! What fun.

 

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Pollination tricks

Flowers are a plant’s way of sexual advertisement. They are evolutionarily designed to attract animals that visit the flower in hopes of collecting nectar or pollen to eat, inadvertently accomplishing pollination. Insects are the most common type of animal that provide this service for flowers, although some insect visitors are thieves, taking the food but without pollinating.

To accomplish pollination, the foraging insect, as it rummages around inside a flower, incidentally gets pollen on its head or body or legs from the male parts (called anthers) of a flower and accidentally brushes off the acquired pollen on a receptive surface (called a stigma) of the female part of a flower. Many flowers have the means of avoiding self-pollination (within the same flower or between flowers on the same plant) and promoting cross-pollination from another plant, which creates greater genetic variation among offspring, one of the chief advantages of sexual reproduction. But that’s another, long story, so here I’m focused just on some behavioral interactions of insects and flowers.

Flowers have evolved many ways of controlling the visits of their pollinators, so the insects enter the flower in a particular way that effectively removes pollen from the anthers and deposits pollen on a stigma. The variety of ways in which plants do this could be the subject of several books; indeed, Darwin wrote one just about The Various Contrivances by which Orchids are Fertilised by Insects.

I’m not about to write a whole book here, so I’ll just describe a few ways some of our local flowering plants accomplish pollination. Open, saucer-shaped flowers are available to most insect visitors. A rose, for example, produces anthers and stigmas right in the middle of a circlet of petals, and all an insect has to do is walk around in the middle of the flower, sipping nectar and casually picking up or depositing pollen when it happens to contact the anthers. Nothing to it! Almost any bug can do it.

Much more interesting and intricate mechanisms of pollination exist in our local flora. For example, twayblade orchids grow profusely in young conifer forests, such as in Gustavus or near Eagle Glacier cabin. The flowers are tiny, pollinated by very small bees and flies. When the insect seeks nectar, it triggers the explosion of a drop of sticky stuff that picks up pollen on its way out of the flower and sticks the pollen to the head or eye of the insect, where it is cemented. Some parts of the flower actually move apart in order to make space for the exploding drop and pollen to emerge and fasten to the insect. Later, when the insect visits another twayblade, the pollen is detached somehow and deposited on the stigma, sometimes leaving the congealed sticky blob behind on the insect. Darwin spent a lot of effort figuring this one out!

A very different pollination mechanism is used by lupines, which are pollinated by bees. The sexual parts are hidden away in a fold between two fused petals in the lowest part of the flower. A bee pries open the fold as it probes for nectar. When it does so, out pop the sexual parts, and pollen can be dusted on the bee or brushed off the bee onto the stigma. When the flower has been visited, the uppermost petal has turned from white to pinkish-purple. The color change is a signal to future bee visitors that the nectar is depleted and the bee should visit other flowers on the stem.

Louseworts, in contrast, hide the sexual parts in a little hood in the upper part of the flower. So a visiting bee has to get into the flower in a certain way, often wedging open the hood, in order for its body to contact anther or stigma. One of the louseworts in Southeast, however, does it differently, as described the next paragraph.

“Buzz pollination’ is one of the most interesting and common pollination mechanisms in our area. In this process, a bee (usually) lands on the flower and buzzes in a special way. Its major wing muscles are temporarily inactivated, and its body just vibrates very rapidly, repeatedly hitting part of the flower. The vibrations shake dusty pollen onto the bee’s body, to be deposited eventually on a stigma. (Obviously, this technique doesn’t work with sticky pollen). Buzz pollination is how shooting stars, tomatoes, blueberries, wintergreens, and many other flowers get pollinated. Buzzing may also contribute to pollination even in open, saucer-shaped flowers such as salmonberry and roses.

Bog laurel. Photo by Bob Armstrong

Bog laurels grace our muskegs with their pink, wide-open flowers. If you look closely at a young flower, you would see that the female parts are in the center. But the male parts consist of arched, white filaments leading from the flower center to small, dark blobs (the anthers) that are nestled in pockets on the surface of the petals. When a bee lands on the flower, the spring-loaded filaments straighten, raising the anthers, and shaking pollen on the buzzing bee. So you can tell if a bee has been there by looking at the position of the filaments (arched or straight) and seeing if dark anthers remain in the petal pockets.

 

I’m sure there are other cute tricks by which our local plants contrive to deliver pollen from flower to flower. See if you can find some!