July observations

an insectivorous squirrel, a piscivorous bear, jostling salmon, and ferny thoughts

–Out of the corner of my eye, I noticed a cottonwood branch twitching strangely. I looked up, expecting to see a bird. Instead, there was a red squirrel, bouncing out along the branch, stopping every so often. When it stopped, pieces of leaf fluttered down to the ground. A squirrel eating cottonwood leaves?? But why by-pass most of them, then? I reached for my binoculars and zoomed in.

I could see that some of the leaf pieces were yellow, not green. Then I could also see that the squirrel was not nibbling on leaf stems or leaf blades but rather it seem to be briefly manipulating each chosen leaf. Aha! Yellow leaf bits falling, squirrel picks only certain leaves…That squirrel was foraging for leaf rollers! This seems to be a good year for leaf roller moths, whose caterpillars use silk to bend leaf blades into protective tubes in which they live and feed. But there was little protection from this hungry squirrel, which cruised branch after branch, foraging all the way on juicy morsels of fat and protein.

Mine was not the only such observation: A naturalist friend observed another enterprising squirrel selecting rolled-up alder leaves. The squirrel noisily chewed open the leaf roll and ate the delicacy within, then moved on to more branches and more leaf rolls.

–It’s bear-watching season on Steep Creek near the visitor center, and one day I saw a yearling about twenty feet up in a cottonwood, in an odd pose with its rear end up and head down. Its hind feet were on one branch and its fore feet were on another, lower branch. Those front feet were deftly manipulating a salmon carcass, adeptly turning it first one way and then they other, occasionally flipping it over. The little bear eventually stripped that carcass down to spine and tail and let these remnants drop. Then it spent several minutes cleaning up its front paws and scampered up another fifteen feet to have a nap.

Young black bears usually separate from their mothers in their second summer. By then, they have learned a good deal about suitable foods and foraging, but they sometimes have a little trouble getting enough to eat. This little guy seemed to be doing just fine. However, it looks to be a rather poor year for berry crops, so it will be interesting to see how yearlings do this fall.

–While I was at Steep Creek one day, I watched the sockeye as the females were tail-flapping to disperse the sediments so they could lay their eggs in clean gravels, and the males were jockeying for position near nest-building females. Breeding males are deeper-backed than females, because they develop a slight hump on the back. The hump is probably a visual signal to other males, making its owner look big and hefty. Male pink salmon commonly develop such large humps that one of their other names is ‘humpy.’ But both sockeye and pinks can use the hump in the same way: when two males are side by side, contending for access to a female, the male with the taller hump leans over the smaller male in a literal put-down.

The first time I saw this behavior was while I was watching pink salmon coming into Sawmill Creek in Berners Bay. The male pinks in that creek seemed to have unusually tall humps, perhaps in part because the accessible part of the stream is quite short and flat, so a streamlined body is not so important. But it could also be partly because competition among males in that stream is, for whatever reason, particularly intense, making a big hump especially advantageous.

It was in Sawmill Creek that I watched a male pink that had such a huge hump that its body was shaped more like a dinner plate than a fish. This male would come closely alongside another male and lean that tall body over the less well-endowed male, forcing the smaller male to lie on its side until it could flap away. Since that time, I’ve seen this behavior several times, in sockeye as well as pinks. It seems to me that this is a form of physical domination, perhaps just short of a direct attack with toothy jaws.

–A friend and I are learning how to identify the local ferns. On a recent walk with that goal, my friend noticed a sizable brown caterpillar on a northern wood fern. The caterpillar was gnawing away at the fern frond, and nearby we saw several other chewed wood ferns. No other ferns on our walk showed signs of insect damage, but a botanist friend recalled seeing severe damage on lady fern on Admiralty Island a few years ago.

Most ecologists seem to agree that, in general, relatively few plant-eating insects specialize on ferns, and ferns get less damage from insects than flowering plants, even though there have been many millions of years for insects to evolve toward eating ferns. So how do ferns avoid heavy damage by insects? One suggestion is that ferns have general chemical defenses that reduce their value as food (just as tannins, for example, make many tree tissues hard to digest) that could be more difficult for insects to overcome than specific toxic defenses such as alkaloids; insects have evolved many specific detoxification mechanisms that allow them to utilize flowering plants that contain toxins.

Early September observations

bear behaviors, sleeping shorebirds, and a diligent squirrel

The numbers of sockeye in Steep Creek had declined markedly, but there were still enough that a female bear with two cubs was able to catch five of them in about thirty minutes. When I came upon them, mama and one cub were busily chowing down on a fresh sockeye, while cub number two was perched up in a big spruce. Pretty soon, mama went out and got another fish—it took her maybe three minutes—to share (somewhat grudgingly, it seemed) with the first cub.

Suddenly, we all heard a loud ruckus just down the trail, as two young bicyclists approached. Fortunately, a ranger was on duty in the area and the raucous disturbance was quelled. But the bears were agitated, and cub number two was sent up the tree to join number one. After a watchful period, the female went back to fishing and caught three more fish in less than twenty minutes, but she didn’t share them.

Another pleasing bear observation: one day I drove up Riverside Drive, with no other vehicles in sight. Out of the brush on one side of the road popped a young bear. It looked both ways, saw me coming, and stopped. I stopped too. Then the bear took another look and rambled safely across the road. A street-wise bruin!

The Crow Point trail near the Boy Scout camp was littered with washed-up, pecked-over chum carcasses. I salvaged some nice clean vertebrae that still had all the ribs and dorsal spines attached: these were useful to me for clarifying a few long-standing puzzles of comparative anatomy—comparing the spinal columns of deer, bears, whales, and whatever else I can get my hands on.

Out on the sandy beaches, I found five dowitchers, all sleeping, with long bills tucked over their shoulders into their feathers. Some were standing on two legs, some on one leg. I was amused to see that as the tide came in, the one-legged individuals just hopped a few steps up-beach without bothering to lower the second leg—which of course was fully functional but resting comfortably up in the belly feathers. I’m not sure the birds even came fully awake—they seemed to go right back to sleep.

Signs of autumn were everywhere: gold leaves of mayflower, orange and red leaves of fireweed, all-shades-of-red leaves of highbush cranberry. Bands of migrating warblers were on the move, searching among the leaves for insects to fuel their southward journey. Mixed flocks of Lincoln’s sparrows and savanna sparrows rustled about in the brush. When I got back to my car, I fund a woolly-bear caterpillar crawling up a rear tire. I suggested to it that a wheel well was probably not a good place to pupate and assisted its transfer to a more productive spot.

Woolly bear caterpillar

Back home, I glanced out a window and saw a red squirrel trying to haul a thick, four-inch-long, white cylinder (maybe a mushroom stem) up a tree. The squirrel was having a tough time with this object, which often seemed to crumble or break, so the squirrel lost its tooth-hold. Somehow, the squirrel always managed to catch the thing when it started to fall, but progress up the tree was slow, irregular, and arduous. But the object got shorter with every attempt to haul it up to the next level; by the time the hard-working squirrel was out of sight, its prize was only about an inch long.

The annual Juneau Symphony whale-watching cruise was a treat: Great food, lovely string quartet, good conversations, and best of all, spectacular whale-watching. Several humpback whales were busy in the area just south of North Pass. All of them were lunge-feeding—making shallow dives and surfacing on their sides with mouths agape as they surged forward. A group of three whales seemed to collaborate; they came up side by side, so close together that it was hard to sort out which jaw belonged to whom. We saw an occasional pectoral fin waving, or half a fluke emerging. This activity went on a good long while; I had never seen such prolonged, concerted lunge-feeding before. We could not identify the prey that was so assiduously sought, but we did not see small fish jumping off to the side in efforts to elude the giant maws (as we often see when the whales feed on schools of small fish), so perhaps krill were the big attraction for the hunters.

Benjamin and North Islands, part 2 of 2

profitable prowlings

One of the special treats of our little excursion to Benjamin and North islands was finding ourselves comfortable in shirtsleeves—no jacket needed, even when crawling out of our tents at six in the morning. How often is it that warm in Juneau!?

In addition to enjoying the marine wildlife, we wandered around on both islands, just exploring. We saw one young deer, with a beautiful summer coat of red, and lots of deer sign. Deer had cropped the leaves of false lily of the valley, occasional stems of twisted stalk, and most of the leaves from sapling crabapple trees. A little stand of skunk cabbage had been reduced to ragged nubbins. Fresh water seems to be in short supply, particularly on North Island, so we wondered how deer would get enough water.

We also found skeletal evidence of four long-dead deer, some apparently quite young, leading us to speculate about hard winters in these sites. Two lower jaw bones caused us to query ADFG when we returned. One of the mandibles we found had four cheek (grinding) teeth in place plus a fifth one just erupting at the back of the jaw. A mature deer lower jaw holds six cheek teeth (three premolars and three molars), and the full set is in place at an age of about two and a half years. The jaw with the just-erupting fifth cheek tooth had belonged to a young deer, perhaps nine to twelve months old, according to ADFG.

The ground, in some places, was riddled with small holes, just the right size for a red squirrel, but we saw no evidence of current squirrel activity: No busy little fussbudgets chattering at us, no middens of stripped spruce cones, and many of the holes had spider webs across the opening. This year, there are huge numbers of spruce cones still on the trees, so food supply for squirrels should be quite decent. We wondered, then, if there had been squirrels here in the past, but perhaps a year or two of poor cone crops had wiped them out.

Among the rocks on the uplifted beach meadows we startled several good-sized voles, which scooted quickly into handy crevices. How did they get to these islands? They can certainly swim well, but it’s a long distance, for a vole, from the mainland to the islands.

As we stood quietly in a beach meadow with a dense population of lupines, we heard tiny tapping sounds and soon discovered the source: Mature lupine pods were explosively twisting open in the hot sun and the dispersing seeds clattered softly down through the surrounding vegetation. At the upper beach fringe, a stand of cow parsnip presented heads of closely packed clusters of maturing seeds. We were fascinated to observe that each little cluster of seeds resembled a rose, carved in wood. So the whole head was, so to speak, a bouquet of wooden roses. Beautiful!

Some very sturdy, squat plants lined the top of one beach, and bore yellow daisy-like blooms. These beach grounsels, with large, spreading leaves, are very specific to this particular habitat type. Each yellow ‘flower’ is really an inflorescence composed of a ring of showy flowers around a disc of many, small, not-showy flowers, altogether forming the daisy-like composite inflorescence. We noticed that ants were visiting the central flowers, presumably sipping nectar. What an odd place to find ants, which don’t seem to be common in Southeast.

On the forest floor were numerous evidences of predation: Three piles of crow feathers (and feet), plus a regurgitated pellet with an intact crow foot. Four piles of gull feathers. Scattered plates of chitons. Sea urchin tests (a.k.a. shells). Some clam shells and small crab legs. Eagles and otters, and perhaps others, had found their dinners.

Other sightings:

  • A row of extremely contorted spruces on a raised terrace well inside the present forest edge. What could be their history?
  • A dogwood bush, normally shrub-sized, but in this instance sending a long branch or two far up along a spruce trunk, almost like a vine. Apparently its only chance to reach the light was to straggle upward, because the dense thicket of young spruce at the forest edge effectively blocked light from shrub-level.
  • An orchid with vanishingly small flowers (with the regrettable name of adder’s mouth), presumably pollinated by insects as tiny as no-see-ums. Could those miserable pests actually have a use?
  • Several specimens of slime mold, growing on fallen logs. One kind was white and spongy, the other was yellow and fuzzy-looking. Spending most of their lives as separate cells in the forest floor, upon some unknown signal the cells come together to form the visible mold, and reproduce.
  • A family of Pacific/winter wrens in a heap of wind-thrown trees, the young ones curious, the parents wary.

From our perspective, our prowlings were profitable. These little explorations are like treasure hunts in which the treasure is unknown ahead of time but recognizable when one sees it.

August Notes

ballistic seeds, a floral show, and a salmon throng

As we wended our way up Gold ridge, en route to Gastineau Peak, we noted some quivering leaves near the ground. Pretty soon, we could discern a slender, furry body moving deliberately from plant to plant. Then a small head with a white eye-ring poked up near a stem of northern geranium, nipped off the fruit, and munched up the seeds. This red squirrel was a long way from any trees, but it was systematically depleting the geranium seed crop, just as if it had come there for that purpose.

The fruit of northern geranium is so distinctive that the plant is sometimes known as ‘cranesbill.’ It consists of a relatively tall spike (roughly an inch tall), at the base of which there are up to five attached knobs, each containing a seed. When the fruit matures and dries, a hinge at the top of the spike loosens abruptly. The spike then splits into several longitudinal sections that flip upward very rapidly. This action elevates the knobs almost explosively, flinging the seeds outward (like an underhand, backhand throw). I know from experience with another species of geranium that the force of the throw is enough to fling the seeds at least twenty-five feet, if unimpeded.

This mode of seed dispersal is called ‘ballistic dispersal. It is found locally in lupine, whose pods twist open forcefully, violets, and impatiens, which is sometimes called ‘touch-me-not” for the way in which the seed capsules pop open. The champion of the ballistics mode, however, is probably a tropical tree called Hura crepitans. The tree makes rock-hard fruits a couple of inches in diameter; the fruit splits into sections (like an orange) when it is thoroughly dry. With a mighty pop, the seeds fly in all directions at high velocity, rattling against the surrounding vegetation. The trick is to bring a few fruits home, put them on the kitchen table to dry, and wait. Then, when no one is mentally prepared, they will go off, startling the daylights out of every creature within earshot, and ricocheting all around the room.

That was a long digression from Gastineau Peak, but I couldn’t resist recalling the fun that Hura’s fruits provided. That was many years ago—these days they might just give me a heart attack.

The route up Gold Ridge provided a good floral show at the higher elevations, including gentians, monkshood, and some still-flowering geraniums. In some dense salmonberry thickets we heard muttering and clucking and peeping, so we knew there had to be a family of grouse lurking under the leaves. Only after we passed by did the hen and big chicks flutter up and over the trail into the brush on the other side.

From Gastineau Peak we looked down into Icy Gulch, where three mountain goats reclined on a green knoll. There was a stiff, chilly breeze that sent us into the lee of a small side ridge for lunch, but the ravens were enjoying it thoroughly, showing off their aerobatic maneuvers.

On another day, a friend and I came down the Fish Creek trail, just because we hadn’t walked it for a long time. Aside from a prodigious mudhole filled with a deep, sloppy, viscous mess (which we reduced somewhat by using some primitive engineering), the most notable observation was the horde of pink salmon thronging the stream up the barrier falls. The banks were littered with long-dead chum salmon, largely intact except for missing eyeballs. The ravens had been foraging selectively for the choice bits of fat that pad the eyes. Dozens of ravens were still there, including what sounded like over-grown but lazy juveniles clamoring for food delivery from their parents. But no eagles.

Strangely, there was no bear sign along the trail, despite the dense crowds of pinks, until we reached the highway bridge. There we found one bear scat—full of blueberry remnants. This begs the question: Why were bears seemingly ignoring the stream full of salmon?