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.

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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.

Early fall observations

swimming squirrels and a deadly flower

All around town, the maple trees are flaunting their famous reds and golds, at least on certain branches. In the forest, devil’s club leaves are turning yellow, setting off the clusters of red fruits and brightening the understory. Highbush cranberry shrubs sport variegated sprays of red and pink and yellow and everything in between, with the occasional bonus of bright red berries. High on the mountain slopes the deer cabbage offers another colorful palette, of orange and russet and gold. In the valleys, cottonwoods and willows are spangled with gold and yellow amidst the bronzy green—visual treats against the backdrop of somber green conifers.

The sockeye run in Steep Creek is finishing, so the bears are roaming around in search of alternate foods, while they wait for the coho to arrive. Bear scats show evidence of much consumption of northern ground cone, with some devil’s club seeds, currants, and highbush cranberries. The fish are few, but one day I watched a familiar female bear run down a sockeye, pin it to the bottom of the stream, and then pick up the flapping fish and tote it into the woods near the observation platform. There she ate the whole thing except the gills, starting with the eggs; one by one, she also lapped up all the eggs that got scattered around in the grass.

Someone once told me, in no uncertain terms, that red squirrels cannot swim—if you throw one into the water, it will just sink. Aside from the fact that most folks wouldn’t do that in the first place, the statement is simply not true (at least if the animal is unhurt). I once watched a red squirrel swimming between two islands in Glacier Bay. And recently I watched one deliberately cross a creek, jumping right in and paddling across. Its tail didn’t even get very wet and its back stayed dry. A very competent swimmer, across the current of the stream.

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Photo by Bob Armstrong

On a walk up the ‘new’ road at Eaglecrest, we found a few late monkshood flowers. No bees seemed to be flying to pollinate them, but we were curious about how the flower ‘works.’ That is, how are the male and female parts arranged, and how would a bee transfer pollen? So we opened up a few flowers. Just inside the natural opening, where a bee would enter, is a tuft of stamens, which would place pollen on a bee as it crawled in. Mixed in among the stamens are the female parts, which would receive pollen. But if male and female parts are in the same place, does this plant pollinate itself or is there some way to avoid self-pollination?

A little bit of research revealed that monkshood species are generally protandrous (first male), meaning that the stamens shed mature pollen before the female part of the same flower is receptive. Bees commonly work from the bottom of the array of flowers, with older flowers, toward the top of the plant, where flowers are younger, so they encounter mature female-stage flowers before they reach the mature male-stage flowers. Before they leave the plant, they pick up pollen from the last-visited flowers. Then, when they fly to the next monkshood plant, they start again at the bottom, where they can deposit pollen from the first plant on receptive female parts of the next plant. In addition, monkshoods are largely self-incompatible: mostly unable to fertilize themselves.

Still to be determined, however, is why the entire flower is so complicated in structure.

Why have that ‘hood’ on top? Those purple petal-like pieces that make the flower are not really petals, they are sepals (parts that are structurally external to the petals; they are green in many other kinds of plants). In the back of the flower, under the hood, are two arching structures that are the true petals, and the nectary is located in a spur at the upper end. But why put the nectary way in back, when the working parts are up front? Bees are said to enter the flower, find the nectar, and then back out the way they came in, passing over the sexual parts as they do so. But the flower does not need to be so complex if that’s all the bees do. Next summer we should try to observe bees as they visit monkshood flowers, to see if we can solve these little mysteries.

By dissecting a few monkshood flowers, we found out that the nectar spurs are quite short, so short-tongued bees should be able to reach the nectar easily, without resorting to nectar theft (chewing through the hood and spur to get nectar without touching the sexual parts of the flower).

But flower handlers beware! Monkshood is very poisonous, and very little of it is needed to produce a nasty effect. Even touching it with your hands and then eating something with your hands, or smoking a cigarette, can apparently have undesirable consequences. Large doses are generally lethal.

One day we walked out toward Herbert Glacier but were thwarted in the last stretch by high water. Along the trail we noted a large white slime mold, artistically draped over a low stump. At several points on the side of the trail were stands of the prosaically named purple coral fungus. It grows in damp soils, sending up finger-like fruiting bodies of a distinctive purple color. It is not to be confused with the unrelated but catchily named deadman’s fingers, which is generally blackish (with a white core) and usually grows on decaying wood. I also found a small specimen of what I think was a white coral fungus. Elsewhere I’ve noted fist- to head-sized clumps of a highly branched yellow coral fungus.