Spring medley

Spring is officially here: the vernal equinox has gone by and the days are rapidly lengthening. There are much livelier signs of spring as well. Sapsuckers have arrived in force, rat-atat-tating on rain gutters and stove pipes (and trees). Juncos trill at the forest edge and song sparrows are tuning up in the brush above the beaches. Pacific wrens sound off from invisible lookouts in the understory. Best of all, ruby-crowned kinglets can be heard, high in the conifers, calling ‘peter-peter-peter’ or singing their full, cheerful song. That’s when spring is really here, for me.

A walk on a favorite beach on Douglas Island was focused on finding mermaids’ purses—the egg cases of long-nosed skates. Every year, about this time, we find them washed up in the wrack at the high tide line—there must be a nursery just offshore. On this day, we found sixteen eggs cases, mostly black, dry, and in various stages of decrepitude. Just a few were still mostly whole and khaki-colored, and two had natural openings at one end, where perhaps the young skate had exited. All the egg cases had sizable holes punched into them. I would love to know if marine predators had nabbed the developing embryos or if the holes were made by a tardy, would-be predator just hoping that an embryo was still inside.

A good find in the rolled mats of rockweed at the high tide line was the body of a sea star, entirely eviscerated. All the gonads and digestive parts had been cleanly removed, neatly exposing the calcareous skeleton of the water-vascular system that runs from the center of the star out into each arm. In a living sea star, the canals of this hydraulic system are filled with fluid, mostly sea water. Numerous branches of the main canal lead to the tube feet (often visible in a live star, in rows under each arm) that function in locomotion and in opening clams. When the tube feet are extended, their ends stick to the rocks or the clam shell, and muscles in the feet contract, pulling the animal forward or pulling the clam shell open. We sometimes see a sea star humped up over a partly open clam while the star is having dinner.

A stroll on the Boy Scout/Crow Point trail led to the goose-flat covered with hundreds of crows fossicking in the dead, brown vegetation. Lots of searching and probing. Sometimes half a dozen crows would suddenly converge on another one, everybody poking at something. Apparently, successful hunts were not very common and the gang thought that sharing was appropriate.

Lots of Canada geese were scattered in small groups on the flats, in the river, and in the vegetation by the river. There were mostly head-down, intent on foraging—grubbing for roots and such, and of course talking to each other. Occasionally, two of them would take off and wing around in a wide circle before landing back where they started. One of these duos took off upstream—perhaps a mated pair about to look for a nest site in the forest.

As we often do, out there, we encountered a fellow we call the Raven Man, who carried a big bag of dog biscuits to feed the ravens. He does this from time to time, and the local ravens recognize him. As he passes through each raven territory, the residents come to greet him and cadge some biscuits. We watched some of these ravens carry five biscuits at a time, first stacking them up in a neat pile so they could be held in the bill. A dog, with some hikers, came along later and sniffed out places where ravens had cached their loot, covering it with grass or moss—surprising the hikers who were not expecting to see dog biscuits in the moss.

Most folks in Juneau are glad to see the snow disappear, at least at the lower elevations. But I loved the good snows we had in February, and here are a few flash-back memories.

–Weasels had been very active in the Peterson Creek meadows and Amalga meadows. They bounded over the clean snow, ranging widely. Every so often, the trail dove straight down under the snow and re-appeared a few feet beyond or disappeared under the overhanging edge of a frozen slough. I think they were hunting voles, whose tunnels run under the snow; did they dive down in response to the sound or fresh smell of vole or were the dives just exploratory? Another treat in one meadow were well-defined trails of mice, showing a good tail-drag.

–On the west side of Mendenhall Lake, one day I found a set of tracks running way out onto the snowy ice and right back again. It was clearly a member of the weasel family, probably a mink. What was it doing??

–A snowshoe trek up a creek out the road was a bonanza of tracks (and no recent human tracks). In the woods on the way up the hill, there were tracks of deer, mouse, weasel, squirrel, and maybe a marten. Big excitement of some large tracks that were surely those of a wolverine—the toes and the gait gave it away. The most fun was seeing a set of wolf tracks coursing over a frozen pond that sparkled with sun-struck hoarfrost.

Now the fun in the snow is finished for the year, and the fun of spring begins. Juneau folks typically love to note the progress of spring, as the season unfolds. Skunk cabbage emerging, pussy willows appearing, blueberry buds expanding, the gradual arrival of more kinds of birds, ravens carrying sticks for a nest—they all mark the progress of a favorite season.

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Rocky intertidal fishes

A trip at low tide to one or our rocky intertidal sites always yields an array of pleasures and some treasures. Maybe I’ll see my favorite bright red hermit crab! Or find an Aristotle’s lantern—the feeding apparatus of sea urchins, which may be all that’s left of the innards of a hapless urchin demolished by a crow. Or maybe I’ll catch a whelk in the act of laying eggs. Always fun.

Lurking under rocks and rockweed, I’ll find small, slender fishes. Sometimes called eels, or blennies, they are neither: in our area, they are usually gunnels or pricklebacks, and I will focus here on some that reside in the upper portion of the intertidal zone. They spend their entire lives in the intertidal zone, which means that they are not submerged in sea water for a significant portion of each day. Of course, the higher up in the intertidal zone they are, the longer the non-submerged period, which happens twice a day. Most fish can’t handle that; we even have an expression “like a fish out of water” to describe someone completely out of his or her element.

Gunnels and pricklebacks, however, deal with low tides just fine. They (and many other species of fishes, of many different kinds) are able to breathe air. Air-breathing fishes around the world accomplish this feat in lots of different ways: for example, some use their swim bladders, or various parts of the digestive tract, or special chambers above the gills. Gunnels and pricklebacks can breathe air, using both gills and skin, as they do in water. Their respiration is reported to be just as effective in air as it is in water, although prolonged stress might alter that.

To begin this discussion, let me present some basics about respiration (in either air or water). Respiration is all about 1) getting oxygen into the body and then to the cells where mini-organs called mitochondria do the work of oxidizing carbohydrates and creating energy to run the whole body, and 2) getting rid of carbon dioxide, which is one of the byproducts of oxidizing those carbos, so that the interior of the cells and of the body don’t become too acidic (which interferes with lots of processes). Both gills and skin perform these functions, but the relative roles of those organs differ among species.

Gills of most fishes are long, thin, and delicate, so as to expose lots of surface area for uptake of oxygen and elimination of carbon dioxide. But such gills tend to collapse when out of water. Intertidal fishes make what is called a ‘trade-off: they have gills that are shorter and not quite so delicate, thus reducing their tendency to collapse, but they sacrifice some of the surface area for diffusion of respiratory gases. Shorter, stouter gills also reduce the risk of desiccation in air.

Both gills and skin need to be kept moist in order for oxygen to diffuse in and carbon dioxide to diffuse out. So when the tide is out, these intertidal residents may dip in and out of tiny pools or roll in wet places, for example.

High cockscomb prickleback. Photo by Bob Armstrong

A common prickleback in our upper intertidal zone is known as the high cockscomb prickleback—named for the prominent ridge on top of its head. That ridge tends to lie flat, however, when this dark fish is not submerged, making confident identification difficult for non-experts, in most field conditions. In this species, females tend to be larger than males (at equal ages), and males compete for mating privileges with females. Large females are especially worth competing for, because they lay more eggs than small females. Eggs are laid under rocks, where the female takes care of them for about a month: coiling around the ball of stuck-together eggs, fanning them to increase flow of oxygenated water, and guarding.

We also see crescent gunnels in the upper intertidal zone. These are sometimes readily identified by the light-colored marks along the sides, but I’m told that some individuals are dark, so discriminating them from other dark species may not be easy in the field. Crescent gunnels have apparently been studied less than high cockscomb pricklebacks, but both parents (but sometimes one or none) often tend the eggs, which are laid under rocks. Most of the other gunnels and pricklebacks in our region are either relatively rare or occupy lower parts of the intertidal zone, and in some of these species, parental care is by the males.

Another small fish is common in the upper parts of the intertidal zone: the tidepool sculpin. As the name tells us, it typically lives in tidepools left by the receding tide. It’s an air-breather too, using the gills, mouth lining, and skin. Sometimes conditions in its home tidepool become low in oxygen or too acidic; this could happen especially at night when all organisms continue to respire and produce carbon dioxide but there is no photosynthesis to use that carbon dioxide. Or sunlight might make the pool too warm. Then these little sculpins often choose to leave their pools, either partially—just exposing the head to air—or fully, resting on nearby weeds or rocks or, occasionally, crawling to another tidepool. They are said to be quite good at homing…returning to their home pond if they are displaced.

This fish is unusual in that males and females copulate and the males’ sperm are deposited inside the female, but the eggs are actually fertilized after they are laid. This is obviously a contrast with most other fishes, in which males and females spawn by releasing sperm and eggs into the water. There is no parental care.

Crow with a prickleback. Photo by Bob Armstrong

These intertidal fishes face many risks in addition to desiccation and respiratory difficulties. Even though they have escaped the many predators in the open sea, there are opportunistic land-based predators that can find them. For example, ravens and crows fossick about in the rockweed and poke under rocks, sometimes coming up with a prize; mink delve into tidepools or turn over rocks. And we who love to explore the rocky intertidal inevitably do more damage than we would like.

Thanks to Dr. K. L. Martin, Pepperdine University, for helpful references and consultation.

Animals at play

Any observant dog owners can recognize the invitation-to-play posture of their dogs, sometimes addressed to persons, and sometimes to other dogs. Surely none of us doubts that dogs love to play, with balls or sticks or each other. And cat owners watch their feline friends toss and chase toy mice, frolic with rumpled scatter rugs, and push pingpong balls under the couch only to fish them back out again. A favorite trick of some cats is ‘ambush’…running ahead of a person or another cat, hiding behind a door, and pouncing out as the victim passes by. Some cats and dogs even know how to make jokes, sometimes deliberately and mischievously misleading their humans or each other in frivolous ways. Of course, dogs and cats are domestic critters, which often have lots of time for frolicking, because they usually don’t have the need to find food or escape from enemies or find mates; the same is true for animals in captivity, which often need sources of amusement.

What about animals in the wild? Do they play too? Sure; especially younger ones, but adults too. Wolves and coyotes tussle and chase. They use the same play-invitation postures among themselves as dogs do; our late-lamented black wolf, Romeo, used to invite passing dogs to play. On-line sources offer plenty of examples: young elephants mud-sliding and mud-wrestling or macaques repeatedly leaping from a tower into a pool of water or….you name it.

Play behavior often has some utilitarian physiological functions, such as muscle toning or sharpening reflexes or improving coordination. It can also have useful social functions, such as learning the rules of interaction among members of a group (e.g., don’t play too roughly!) or establishing a dominance order. But play behavior would not be so common among critters if it weren’t simply FUN.

It took a long time for humans to recognize that animals, both domestic and wild ones, like to have fun. Having fun requires a degree of intelligence that humans have been slow to admit is found in animals—irrationally and wrongly preferring to think ourselves superior to everybody else.

Here are a few examples of animals that play, mostly from animals that we often see around here.

Young marmots box and wrestle on the threshold of their den. Bear cubs tumble and tussle with each other, sometimes engaging mama as well; so do beaver kits and young ones of many other species. Mountain goat kids sometimes bounce from ledge to ledge, apparently just because they can and it is fun.

Young humpback whales sometimes cavort, fluke slapping, pectoral slapping, and breaching, as if saying Hey mom, look at me! A local photographer watched one breach seventeen times in quick succession!

Photo by Doug Jones

We can see ravens having fun. They might fly up with a feather or some other object, and then drop it, only to swoop down and catch it again; or maybe a friend would dart in to snatch it away. Sometimes there is a game of keep-away: I’ve got a toy, you try to get it from me. We’ve watched ravens roll down a snowy slope, or slide like a toboggan, only to trot back up to the top and do it over again.

Crows play, too. There is an on-line video of a European crow sliding down a snowy roof while standing on a plastic lid; then it picked up the lid, went back to the top of the roof, and slid down again. What a hoot! (I couldn’t leave that one out, even though it is not local). Our northwestern crows sometimes dangle upside down from a branch, not reaching for anything nor avoiding something, just showing off. The biggest showoffs dangle on one foot: see what I can do! Then they may swing back upright with a wing-flap or two, or let go and try it again on a different branch.

Otters slide down muddy or snowy slopes. Some slide tracks are many yards long, and the otter then continued onward to wherever it was going. This is an energy-efficient mode of transportation—just push off and let gravity do the rest. But sometimes they are not really going anywhere, just down a small slope and back up again, to do it all over once more. Sometimes a whole slope will be covered with their slide marks. It must be fun!

Dall’s porpoises sometimes come to ride the bow wave of a fast-moving boat. A little group of them seems to appear from nowhere and together they ride that wave, sometimes for a considerable distance. Then they are gone, as suddenly as they came.

One day at Eaglecrest I found a place where ptarmigan had pranced around, leaving lots of footprints. These were interspersed with a number of slide marks, about three feet long, going down a little slope. We know that ptarmigan often glide to a stop when they come in for a snow-landing, leaving a short slide mark, but the marks I saw did not look like landing marks. They made me think of the otter slides, so I wondered if ptarmigan can play too. I turned up only one report, which says that flocks or family groups of willow ptarmigan frolic together, crouching low with head extended, jumping around, and flapping one or both wings. I would love to see that!

Beach-walking in late March

What’s a restless naturalist to do, when most of the ground in covered with soggy snow and strong signs of spring seem reluctant to appear? Although the varied thrushes and juncos are singing, and the skunk cabbage has poked up in some places, some of us get a little impatient for more. One option for our edification is walking the beaches in hopes that something of interest will show up (it almost always does!).

On the way to Crow Point via the Boy Scout trail, small gaggles of garrulous geese flew from the river over to the far end of the wide, flat meadow. (Do they ever stop talking, except maybe when sleeping??)

Crows were beach-combing, dozens of them, all scattered along the line of the advancing tide, perhaps nabbing small prey that were activated by the onward rush of water.

Overhead, winging northward, were three elegant trumpeter swans. Although most trumpeters nest in the Interior, a few nest near the north end of Lynn Canal. It’s always a treat to see them, if only in passing, and that was the main ‘payoff’ for post-holing my way out to the beach. There had been strangely little foot traffic out this way, so post-holing was the only way to go.

On another day, for no accountable reason, I suddenly was possessed of the notion to look for mermaid’s purses. These are the egg and embryo cases of skates (relatives of rays and, more distantly, sharks). So I went to a beach where I’ve occasionally found them before, washed up on a big tide. Bingo! I found four of them: one black, dry, and dead, two much fresher, yellowish green, but ripped open, perhaps by an enterprising raven, and the embryos gone. The other one was intact, and I tossed back into the water, in case the embryos had survived their stay on the beach.

A short chunk of timber had washed up on the shore of Eagle Beach. It was completely riddled by smooth tunnels, about the diameter of a finger. Aha! Teredos had been at work. A.k.a. shipworms, for their unpopular habit of mining into wooden ships, teredos are really molluscs, albeit with a worm-like body. They can get to be over two feet in length, long, soft, and quite slender, with two very small, ridged shells at the front end. Those shells grind their way into wood as a teredo rasps its way along. The wood particles are digested, with the help of symbiotic bacteria that live in special cells in the animal’s gill. Teredos also eat plankton, which are inhaled by a siphon at the rear end of the body, and pass over the gill on the way to the mouth.

A teredo gets its start when a free-swimming larva finds a suitable piece of wood and settles down, attaching itself by means of byssal threads, such as one sees on mussels and other sedentary molluscs. The larva softens the wood at the attachment point, and then transforms into the adult shape and starts boring. Naturally, the tunnel gets bigger as the teredo grows and moves ahead.

Teredos are somewhat related to piddocks, another kind of clam that tunnels into hard substrates (and which have appeared in these essays before). Piddocks are clearly recognizable as a type of clam, but the stout shell is more curved and has ‘teeth’ along the edge. Piddocks use their burrows just for shelter and filter-feed on plankton, like ‘normal’ clams. A likely evolutionary link between teredos and ordinary piddocks is a group of distinctive wood-borers that use symbiotic bacteria to aid digestion, as teredos do, but the shells are more complex and substantial than those of teredos, a little more like the huskier ones of piddocks. Tunneling into wood (and rock, in the case of piddocks) is the way of life for a considerable array of clams, apparently, a surprising twist on our conventional view of more familiar, sediment-dwelling clams.

At Twin Lakes, the ice was dotted with open holes. A friend watched a river otter that was actively fishing—it caught and ate almost a dozen fairly small fish in a couple of hours. Then it caught a starry flounder; an eagle was watching and came down to snatch it away, but the otter saw the eagle coming and dove quickly, holding onto its prey. Later, the otter caught a big staghorn sculpin, hauled it out onto the ice, and began eating it, looking around for that thieving eagle. Down came the eagle, very fast, and ripped the sculpin right out from the otter’s feet. The otter dove beneath the ice, and the eagle had a good breakfast.

The moment before the theft. Photo by Jos Bakker

Thanks to Aaron Baldwin, ADF&G, for expanding my knowledge of teredos and their relatives.

Four bird-baby stories

Spring is the season of babies, in the woods, on the beaches, in the ponds and meadows. Baby birds can be great fun to watch. Here are four little stories about them.

–After watching the shenanigans between male and female mallards on my home pond, followed by lazy males loafing around with each other, I finally got to see what I was waiting for: seven tiny ducklings scooting around the pond. They seemed to be totally unsupervised; no mama was in evidence. So the little fellows skittered all over, jumping up to catch a bug on an overhanging alder leaf, streaking across the water for no obvious purpose, nibbling small things along the shore. After some minutes, a female appeared from downstream. But she ignored the ducklings and hobnobbed with another female; they foraged together on the shoreline vegetation in apparent amity. Two males sleepily lurked in the brush at the upper end of the pond, ignoring everybody else. Eventually, one of the females rounded up the fuzzy little ones, and they all disappeared.

–A few days before the little duckies appeared, I watched a female junco feeding on some spilled seed, while her fledgling danced all around her, begging—beak open, wings aflutter. She turned her back, it scuttled around in front again; she turned away, it sidled around to face her. This litte dance repeated itself several times. The kid was perfectly capable of feeding itself, and did so occasionally, but it wanted mama to provide. Mama did her best to ignore the importunate youngster, but occasionally gave in and poked a seed into the little beggar.

–A friend found a crow nest, tucked under a good-sized log. A nest on the ground isn’t the usual thing for crows around here; mostly they seem to nest in densely branched spruce trees. Sometimes several nests are fairly close together, in adjacent trees, forming a loose colony.

Some days after the discovery, we went back to look for the nest. Meanwhile the vegetation had grown exuberantly, so the sheltering log was invisible. So we hunkered down behind some bushes and kept watch for the parental crows. Eventually they came in, bringing food for the chicks, and after several feeding trips, we had the nest location pretty well pin-pointed.

Photo by Bob Armstrong

After the adult crows had left the area to find more food, we walked up the to spot, parted the surrounding vegetation, and peered under the log. There were two big, well-feathered chicks with bright blue eyes, staring warily up as us. I bent down low, and discovered that there was a third chick, less well developed than its siblings, cowering in the ‘back room’ farther under the log. The third chick may have hatched a bit later than the other two and, because it was therefore smaller, it was likely to be last in line when the parents brought food. If food is scarce, it may the first to die. Because the usual clutch size is four or five eggs, it is possible that other runts may have already died. (Or maybe I just can’t count higher than three!).

–Near the Visitor Center, I accidentally discovered a yellow-rumped warbler nest, wedged into the fork of a tall willow tree. I think they had very young chicks at that time, and during the following days, they grew rapidly. Soon four tiny beaks could be seen, reaching up above the rim of the nest when the parents came to feed them. A day or two later, fuzzy, downy heads were visible. A few days more, and the nest was starting to collapse on one side. Two hefty, feathered chicks held tight to the tipped bowl, while two more huddled just outside and behind the upper rim. A couple of days more, and they were gone.

Yellow-rumped warblers are widespread, but their plumage and songs vary geographically. At present, this variation is represented in about four subspecies, which are known to interbreed at times. The adult birds at this nest were interesting: The female seemed to be a typical ‘myrtle’ type, with a white throat. At first glance, the male appeared to be another subspecies, called ‘Audubon’s’, with a yellow throat. But one of Juneau’s top birders suggested, after seeing photographs of the head markings, that the male was probably an intermediate form, perhaps a result of previous hybridization between myrtle and Audubon’s. Apparently this pair was busy rearing more intermediate forms of this species.

Bird Brains

When someone does something stupid or behaves in a scatter-brained way, we may jeeringly, scornfully, call that person a ‘birdbrain’! But wait a minute: is that epithet really accurate or fitting? Consider some of the amazing things that avian brains accomplish!

Chickadees, nuthatches, and corvids (jays, crows, ravens) cache food and can remember hundreds and thousands of cache locations for weeks and months. Clark’s Nutcrackers (another corvid) spread their hidden stores of pine seeds over many square miles and can retrieve almost all of them, even after several months. That’s a lot better than what many humans could do, even with practice.

Crows of various species have shown considerable ability to figure out problems that require insight. New Caledonian crows invent new ways of extracting a food item, by using a sequence of tools in the appropriate order. They can do this without practice, sometimes even inventing tools. For instance, one of these crows figured out how to use a little hook to extract a tiny food basket from inside a container, and when such a hook was not provided by the experimenter, the crow made one from a straight piece of wire. European rooks invent tools too and use them in novel situations; a rook quickly figured out that it could raise the water level in a beaker by dropping stones into the water, thus raising a floating food item up where the crow could get it. Crows in Japan drop nuts in front of traffic, letting the vehicles crack them open; if the vehicles miss a crow’s prize item, the crow may pick it up and drop it in the traffic lane again. This is a relative new trick, just developed a couple of decades ago, and it shows that the birds are capable of insight.

Some birds (parrots) are capable of reasoning by analogy. For example if items A and B are different from each other, but C and D are identical, these birds learn the concept of ‘different’ and ‘same’ and can apply it to a novel situation, recognizing that items W and X are different but Y and Z are the same. Thus they show some ability for abstract reasoning. I know some otherwise apparently normal humans that would have trouble doing that!

Many birds are capable of observational learning—watching another bird do something and copying what they see–and some birds (parrots, some songbirds) can copy sounds or songs too. Many mammals cannot do this. Certain birds go on learning new songs all their lives: canaries learn new songs (and grow new neurons to do it) every year, replacing the old neurons and songs, while mockingbirds and parrots can go on increasing their repertoires throughout their lives.

The tiny brain of a hummingbird (smaller than a pea) is capable of guiding the bird on extended migrations, up and down the Pacific Rim in the case of our rufous hummer and over the Gulf of Mexico in the case of the ruby-throated hummer. No mean feat!

All that is not to imply that bird brains are like human brains. Like our brains, bird brains do have right and left sides, which function differently. But birds have considerably bigger brains, relative to body size, than humans do. As in all vertebrates, bird brains are divided into three parts (fore, mid, and hind) and in both birds and mammals, it is the forebrain that is specialized for ‘smarts’. In birds, however, it is the so-called hyperstriatum (an inner part of the forebrain) that provides what we call intelligence, whereas in mammals it is the cerebral cortex (the outer part of the forebrain). (But contrary to what you might read on Wikipedia, bird brains are NOT located in the thorax!)

So, the bottom line here is that bird brains are really not to be scoffed at. Perhaps they should even be admired for some of their amazing accomplishments! Humans have had a hard time learning that other animals have talents, skills, wit, and emotions, worthy of respect, even though Darwin paved the way over a hundred and fifty years ago. We can be very slow learners, despite our much-vaunted gray cells. Perhaps there is a lesson there!