On the trails in late May

springtime, from the subalpine to the shore

When I got up that morning and looked out the window, rain was cascading down. This is spring, so I really didn’t want fall weather. But I glumly packed up my gear, somewhat grumpily donned my rain pants, made sure my rain jacket was in the car, and went to pick up some Parks and Rec hiking friends. By the time we reached the Perseverance trailhead, the sky was blue, the sun had climbed over the ridges, and with smiling faces we headed up the trail (after greeting the large, furry, white dog that lives in the Gold Museum and likes to check out folks at the trailhead).

Spring is always quite exciting, because there will be something new to see or hear or smell almost every day. In the past two or three days, leaves had fairly leaped out of their buds, and cottonwood leaves glittered in their new-green hues. Salmonberry canes sported their first pink flowers, and clumps of shooting stars decorated the trailsides. My favorite yellow violet was in good flower, along with the small-flowered lavender one. The air was fresh with the delicate fragrance of cottonwood resin (on the bud covers) and the sweet perfume of skunk cabbage (nothing the least skunky about it!).

Robins carried food to their chicks, and parental varied thrushes clucked warnings to their newly fledged youngsters. Wilson’s warblers chattered on all sides and a few yellow warblers announced their recent arrival. Fox sparrows held shouting matches (in song) in the thickets. Ruby-crowned kinglets gave many variations of their rich, musical song. A few hermit thrushes fussed in the underbrush but did not sing. A pair of harlequin ducks loafed on a midstream rock, presumably with thoughts of eggs to be laid in a nest not far away.

Where Lurvey Creek joins Gold Creek, I gazed upstream for half an hour and was finally rewarded by a small gray bird that darted out of a crevice in the cliff and perched on the deep snowbank that lined one side of the creek. Dippers often nest here, except in years when snows still cover the entire creek. A snow-bridge below the dipper’s nest site collapsed bit by bit and sent snow-bergs downstream, as we enjoyed a leisurely lunch with homemade cookies.

American Dipper. Photo by Arnie Hanger

If we had been there two days later, things would have been really exciting. Big slabs on the flank of the ridge loosed their moorings and slithered down into Gold Creek, just above the junction with Lurvey Creek. A deep mound of dirt and boulders now squats over the creek, which has carved its way through the debris. Gold Creek was turbid for several days, and this is likely to continue for a while, given the size of the dirt pile. The heavy sediment load is probably bad news for the dippers trying to nest downstream, because the water is too opaque for them to find their food.


A warm day or two later, I was on the West Glacier trail, finding the first baneberry flowers, lots of buttercups, more violets, and batteries of white butterflies looking for mates and visiting the violet flowers. On damp, rocky sites we found clumps of a flowering plant that was new to me until very recently. It goes by the utterly silly common name of Sitka mistmaiden (more formally known as Romanzoffia sitchensis), and it looks enough like a saxifrage (which it is not) to fool a botanist. This trip had the ultimate goal of checking for a dipper nest at a stream that plunges off Mt McGinnis into Mendenhall Lake. And indeed, the birds were there, although this year the nest was in a new site across the creek. I think that dippers started nesting by this stream as soon as the glacier left the site open.

The next Parks and Rec excursion was a stroll out to Blue Mussel cabin on the shore of Berners Bay. Overcast skies kept the temperatures relatively cool, and mist lay low over Lynn Canal. We gobbled up a homemade rhubarb dessert (yes, mom, even before ‘cleaning our plates’), as small squads of sea lions foraged enthusiastically and a humpback whale made unexpectedly tight turns in pursuit of the same small fishes.

Although our spring arrived late this year, the meadows were awash in pink-flowered shooting stars. Bright yellow buttercups dotted the fields of pink, yellow marsh marigolds adorned the wet ditches, and the yellow display of skunk cabbages attracted the usual crowds of small, brown, pollinating beetles. Lupine was just beginning to bloom, but these early blooms had already been visited by bumblebees, turning the upper petals from white to magenta.

I heard a snipe performing its great aerial display, but I think I was the only hiker who noticed this. Savannah sparrows sang and flitted low in the herbage, and I heard a distant burbling song of a Lincoln’s sparrow (but I had to think hard for a bit before I could pull that one out of my so-called memory!). And I have not mentioned the mosquitoes…

On the walk between the beach berm and the Blue Mussel cabin, we encountered several signs that the trail is also used by bears. There was a strange, barren patch of forest, in which there was no ground cover and all the smaller trees were quite dead. It looked as if a ground fire had passed through, but there were no signs of charring, leaving the cause an open question.

Considerable work has greatly improved the formerly squishy trail between the Cowee Meadow cabin and the beach berm, where sweetgale was just leafing out. However, parts of the trail through the meadows were ankle-deep in water, nicely contained between the logs that mark the trail edges. A few more loads of gravel between the logs in these sections would surely be appreciated!


Staghorn sculpins

the interesting life of a perhaps-underappreciated fish

There are many species of sculpins in Alaska, mostly living in intertidal zones. One of the species a shore-bound person is most likely to see is the staghorn sculpin, so-called for the little ‘horns’ or spines on the rear edge of the preoperculum (a bone that helps cover the gills). Staghorns can be as long as 46cm and many live for several years. They are common in estuaries, but venture into fresh water as juveniles. As they grow older, they may move into deeper marine waters, down to about 50m, but many spend their lives in estuaries.

They don’t have any scales on their bodies, like some other sculpins, but which is unusual among fishes. They have very large pectoral fins that can be fanned out to the side. These are used for locomotion (forward or back), gliding down to deeper waters, or propping themselves up on a rock while they wait to spot a tasty prey item.

I got interested in staghorn sculpins after observing American Dippers capture them. Dippers often eat small fish, up to four or five inches in length. That’s a lot of fish for a bird that only weighs a couple of ounces. So dippers generally pound a captured sculpin on a handy rock, sometimes thrashing it as long as ten minutes. This subdues the squirming fish, makes the fins relax, and eventually may break the fish’s body into pieces, which are then consumed. A small sculpin, however, may be swallowed whole, headfirst, after being subdued. In winter, dippers often forage in estuaries, so sculpins are captured rather regularly.

These sculpins mature at age one year, and keep on growing. A large female can lay up to 11,000 eggs; some sculpin eggs are poisonous, but I have not been able to confirm that for staghorns. As in most (but not all) sculpins, in this species eggs are fertilized externally, as males and females just extrude their gametes into the water, during the winter months. The eggs are laid on rocks, where males tend them for about two weeks, depending on water temperatures. The larvae eat plankton and are found chiefly above the bottom. They turn into juveniles when they reach about 20mm in length and into adults at about 120mm in length. Juveniles and adults live on the bottom, where they eat amphipods, shrimps and crab, and worms; large juveniles and adults eat fish and large crabs.

One of their more interesting ways to feed themselves is by nipping off the siphons of clams. Reportedly, if a staghorn chances to bite the siphon of a butter clam that carries PSP, it may avoid them thereafter; although it will continue to eat siphons of clams that do not carry PSP. So PSP may help protect the clams from sculpins! If staghorns are prevented from chomping on the siphons of littleneck clams, these clams can then grow at twice the rate of clams with nibbled siphons. So there is a big cost to getting chomped by sculpins, and protection would be valuable.

Staghorn sculpin are eaten by many different marine mammals and birds, including large fishes (other sculpins among them), ducks, loons, herons, cormorants, pigeon guillemots, river otters, and sea lions. They are so vulnerable to predation that they have several means of trying to protect themselves. They may try to avoid being captured by partially burying themselves in bottom sediments. This doesn’t always work. And they erect those spines, with the sharp ends pointing up, if somebody threatens or grabs them. But some predators know how to avoid the spines. In addition, staghorns are cryptically colored in blotchy browns and grays, which makes them relatively inconspicuous. I would like to know if staghorn sculpin can change color, as some other species of sculpin do.

River otters are fond of staghorn sculpins. Photo by Bob Armstrong

Researchers at UAS have studied cryptic coloration in another species of sculpin, the coastrange sculpin. This is a freshwater species that is also cryptically colored. Coastrange sculpins can change their colors to match the bottom of the stream, becoming darker or lighter, depending on the background. Some color changes take weeks, because new pigment cells in the skin have to be created or destroyed. But these sculpins can also change color quickly, in just a few minutes, by expanding or contracting the pigment cells. Some individuals are able to make greater changes than others. For example, small sculpins tend to be able to make greater color changes than larger ones.

The value of color shifts became apparent in simple experiments showing that light-colored sculpins on a dark background and dark sculpins on a light background were more often attacked by predators than sculpins that closely matched their background. Thus, the ability to change color is clearly adaptive. Interestingly, fish from a turbid stream with little overhanging vegetation exhibited more variation in color change than fish from a clear stream with lots of nearby vegetation. The researchers suggested that there would be a lower risk of predation in the turbid, unvegetated stream, because the sculpins would be less visible and there would be fewer predators. As a result, the ability to make rapid color changes when a sculpin changed its position and therefore its background, was less important there. Therefore individuals of differing ability to color-change could remain in the population. Where the risk of predation was thought to be greater, the researchers suggested that all individuals would gain protection by the ability to change color rapidly whenever they moved around, so there was less variation among individuals—the individuals that couldn’t change rapidly got eaten. Natural selection at work.

This work was done largely in Glacier Bay, which has been gradually deglaciated in the past two hundred years or so, and streams near the mouth of the bay are older than those near the still-receding glaciers. As a result, streams near the glaciers are turbid and surrounding areas have little vegetation, while streams near the mouth of the bay are clear and well vegetated. As the streams age, the risk of predation and the color of the stream bottom change, so the ability of sculpins to change color probably has helped them to colonize streams in the bay.

Gastineau Channel

abundance of life along Juneau’s busy waterway

In late April and early May, Gastineau Channel is notable for the large aggregations of scoters. They raft up in hundreds and thousands at the mouths of Gold Creek and Sheep Creek. Most are surf scoters, whose males are distinguished by the white patches on the heads. Less common are the white-winged scoters, whose white wing patches are best seen when the wings are spread. Only careful inspection would tell if there are a few black scoters mixed in the flocks.

Surf scoters in Gastineau Channel. Photo by Bob Armstrong

Scoters are chunky, heavy-bodied sea ducks that winter along the coast. Those that winter to the south of us migrate northward in spring, often stopping to refuel in our area, toward their nesting grounds in the Interior. Canadian researchers have found a tendency for scoter migrations to follow the timing of herring spawning, which is generally later on more northerly coasts. Herring spawn is a favorite food of scoters.

On a low-tide morning in early May, a couple of friends and I walked down the beach on Douglas Island to Ready Bullion Creek. We went to see if dippers occupied their usual territory on the lower part of the creek. And yes, they were there, but they seemed to be nesting in a new site. The new place is one that for several years I thought would be ideal for them, but they had preferred to nest either down close to the intertidal or well upstream in a very narrow canyon. This time the nest site is between the former sites, on a cliff next to a nice waterfall and above a beautiful pool. (I finally got it right!)

As always, there were interesting things to be seen along the beach: two eagles with locked talons, spinning downward and breaking off just before crashing into the beach logs; a couple of migrating golden-crowned sparrows in the brush above the beach, on their way to the Interior and the subalpine habitats around here; male cottonwood trees starting to flower; a greater yellowlegs standing in the shallows; a pair of hooded mergansers flying by.

Small flocks of Barrow’s goldeneye cruised slowly along, in some cases in the company of a few pairs of harlequin ducks. The goldeneyes nest mostly in the Interior, but sometimes they nest in coastal areas—and at least occasionally in the Dredge Lake area. The harlequin females will go up along the coastal streams to nest, and (with any luck) they’ll bring flotillas of ducklings down to the sea later in summer.

The beach was covered with strange little tracks, which we deduced were those of crabs scuttling to and fro. A raven had marched in a straight line for many yards, and a deer had run down the sand. In one area, numerous holes in the sand, many of the surrounded by a tiny turret of slender, cylindrical fecal castings, may have indicated a population of some kind of worm (my ignorance is showing!).

The most interesting part of the beach was a shallow bight whose shore was densely occupied by sea stars. Many of the stars were steeply humped up over cockles or mussels (alive, alive oh!), having breakfast. They will also eat chitons, sea squirts, and limpets; the escape reaction of limpets is worth trying to see – they try to avoid the attacking star by ‘galloping’ away at Olympic speeds (relatively speaking, considering that they lack legs…). We noticed that quite a high proportion of the common five-armed star had only three or four arms, having lost the others to a predator (gulls, king crabs, other stars). Sea stars can regenerate lost arms, in time, but I wonder if there is a loss of efficiency in opening mussels or clams when there are fewer arms to pull open the shells. One sea star had a supernumerary arm, apparently regenerated from the side of a normal arm.

These sea stars displayed a remarkable array of colors—bright orange, dull orange, gray, brown with blue highlights, purple, brown with black bands across the arms, brown with dark blotches (like a rattlesnake, said a friend). It is highly unusual for any species to show such a diversity of colors. In the case of sea stars, it may be due, at least in part, to what they have been eating. And that may explain why an individual star can, reportedly, change color during its lifetime, and why a regenerating arm can be a different color that the rest of the star. A study of another species of sea star showed that diet had a big effect on the color of the star, although other factors must also be involved. I wonder if color has any effect on the risk of predation!

Parental care by males, part 2

these are not deadbeat dads!

This essay will consider male parental care in birds and mammals. Both birds and mammals evolved from reptiles, and some ancient reptiles did have parental care by at least one parent, but modern reptiles have no record of male parental care, so they will be ignored here. As is true for fishes and amphibians, the factors that govern the evolution of patterns of parental care are no doubt several and still subject to debate and future research.

Biparental care is the usual thing among birds: both parents tend the young in over ninety percent of bird species. Females often do the incubating of eggs, but her male may feed her while she does so and the males generally help feed the chicks. This is the case for American dippers, for instance; as one of my field techs said, during our intensive study of this species: there are no dead-beat dads! In fact, we even know of one hard-working dad who raised at least a few of his chicks by himself, after his mate disappeared. The emperor penguin male goes a step further: he incubates a single egg on his webbed feet while his mate goes off to sea and feed; then they both tend the chick.

In some taxonomic groups of birds, including hummingbirds and grouse, females generally do all the work while the males run off to find more females. But even in these groups, there are unusual species in which both parents provide parental care; the willow ptarmigan is a local example.

Still more unusual are avian species in which males both incubate and tend chicks by themselves. Here a few examples. Spotted sandpiper females often lay one clutch of eggs and leave it to the male to do the incubation and guarding while she proceeds to lay another clutch (with the same or a different male) that she incubates and tends; this is a pattern found in several shorebirds.

Spotted sandpiper nest–is this tended by the dad? Photo by Katherine Hocker

In two of the species of kiwi in New Zealand, the Australian emu, and several other species, males incubate and tend the chicks alone. The cassowaries of Australian and New Guinean rainforest also have hard-working males, who incubate the eggs for weeks and then tend the chicks for months. They are fierce defenders of their little families: One day in the Australian rainforest I encountered a cassowary family; we were all looking for fallen fruits. Imagine looking up from the forest floor and seeing a very large bird, almost as tall as you and with claws that could rip you open, glaring at you from just a few short yards away. You can bet I apologized for my presence most abjectly and discretely retreated rather quickly!

What about the mammals? Virtually by definition, females are the ones that feed the infants, and lactation is considered to be the single most expensive thing a female mammal ever does. Dependence of the infants on mother’s milk means that females are always involved in parental care, so uniparental care by males is not an option. Biparental care is not common, but males are reported to be closely involved with parental care in about five percent of all mammal species. The best known cases include carnivores and primates, but regular male care occurs in other groups too. Here are some examples:

Among the carnivores, the males of foxes and wolves regularly bring food to their young. Asian raccoon dog males participate in all forms of parental care except lactation, and also tend the female during the birth process. Male members of packs of African wild dogs bring food to lactating mothers and young pups.

Male baboons and macaques carry babies around, which may help protect the infants from predators or intruding strangers. However, this situation is more complex than that, because the male may obtain direct benefits too: a male with a baby in his arms suffers less aggression from other males and may also gain favor with the infant’s mother. And if there is a fight between males, the infants are in great danger. In some small New World primates called tamarins, including the cotton-top tamarin, males regularly carry and care for babies. Males of the endangered pied tamarin reportedly do most of the parental care except for lactation.

Wild horses and zebras live in groups, often a male’s harem of females plus foals. Males defend their foals and females from predators.

It’s a rare herbivore that helps feed the young ones, but male beaver do: they regularly help build winter caches of branches on which the whole family, but especially the still-growing young ones, feed; they also help maintain dams that make the pools that protect the lodge and facilitate transport of branches. They stay with the rest of the family in the lodge over the winter, interacting and providing body warmth. Among the smaller rodents, males of the California deer mouse reportedly brood the young, keeping them warm until they can regulate their own body temperature. Prairie vole males cache food, brood and groom the babies, and even retrieve them if they wander out of the nest.

Early July scrapbook

a friendly dipper, sparrow city, swallows, ducks, warblers, and a balancing bear

The holiday week in early July found me on several short excursions. A trip to Lurvey Falls near the end of the Perseverance Trail was particularly rewarding for an old dipper-watcher and companions. As we approached one of the wooden bridges in the upper basin, we noticed a young dipper perched on the edge of the planks. So we stopped and ‘froze.’ Pretty soon the juvenile was pecking at the surface of the boards, poking down in the cracks between the boards, and being quite successful at finding little edibles—and discarding a few inedibles. It foraged this way for some minutes.

Then it hopped up on the bridge railing, picking up tiny things as it moved along. Gradually, it got closer and closer to us, until it was right next to me, just below my hand—and it nabbed a bug off my jacket before leisurely hopping back along the railing. What fun!

We think we found its parents a little way upstream, carrying beakfuls of bugs in both directions, up and down the creek. They appeared to have fledglings scattered all along the creek, and our insouciant juvenile was probably one of them.

A walk on the wetland at the end of Industrial Boulevard brought me into ‘sparrow-city.’ Song sparrows lived in the very brushy zone of alders and willows. As the thickets became sparse and mixed with grasses and herbs, I found a few Lincoln’s sparrows. Out in the open meadows, there were dozens of savanna sparrows, some singing and others with beaks full of green caterpillars and long-legged crane flies for their chicks.

Nest boxes on stakes were occupied by tree swallows. As I walked on the trail past one box, an agitated adult swallow dove close to me head repeatedly, until I moved along a sufficient distance from its nest. Another box seemed to have produced some fledglings that did not venture very far away and were actively tended by busy adults.

Tree swallow on nest box. Photo by Katherine Hocker

Some of the old, upturned snags and stumps scattered around the meadow are pieces of sculpture, if you take time to look. Beautifully curved roots, almost muscular-looking, once held those trees in the ground. Now they support mosses and lichens, and lots of tiny red mites.

My home pond has hosted at least three broods of mallards, all of different ages. Only two juveniles were left in the oldest brood, now almost as big as mom, with bodies well-feathered but wings still too short for flight. Five downy, middle-sized ducklings were just getting real feathers. And a brood of seven tiny fluff-balls arrived with their very vigilant mother. On most days, only one family used the pond at a given time, and if there was a brief temporal overlap, the females kept the broods well apart.

As usual, visits to the glacier area provided entertainment. The terns had gone, but barn swallows were nesting in the pavilion and exercising mosquito control in long, graceful swoops. A brood of mergansers rested, with mom, on a rock. A downy Barrow’s goldeneye duckling foraged alone for days, no family in sight, but apparently doing well for itself. A myrtle warbler (a.k.a. yellow-rumped warbler, a.k.a. butter-butt) flitted along the roof edge of the pavilion, gleaning insects. One aerobatic warbler chased flying insects high above the pond made (but no longer occupied) by beavers; it flew so high that it was just an animated black spot, diving, circling, climbing, and looping.

An adult black bear had climbed to the very top of a cottonwood tree. There it chewed through several inches of wood, causing the tip of the tree’s trunk to fall. The bear caught the falling piece and promptly ate the seed pods. Then it moved down to a sizable side branch. Planting its rump firmly in the junction of branch and trunk, it started to chew off the branch. Deciding, apparently, that this part of the branch was too thick, it reached out another foot or so, and chewed again, but briefly. Again, not satisfactory. So, stretching out as slender as a big bear can get, and balancing well along the branch, it gnawed through the branch at a thinner place, brought it down, and again gobbled up the seed pods. The top of the tree was a wreck, and the bear slid down and wandered off into the woods. Watching the antics of bears in the trees can be as much fun as watching them in the creek later in the season when the fish arrive.


divers and burrowers

I’ve been thinking about kingfishers lately, although I don’t know what brought them to mind. I certainly haven’t seen any recently—their freshwater fishing spots are mostly iced-over, so they are out along the saltwater shores where I seldom go. Our species is formally called the Belted Kingfisher; males have a blue belt and females have both a blue and a rusty-orange belt across the belly.

With kingfishers on my mind, I found I was recalling a nest I once found. Several years ago, while we were deeply involved in a study of American dippers, I was watching a pair of dippers that had a nest in an old broken-down wooden dam. I sat on a brushy cliff above the nest site, watching the dippers go about their business of raising a family. The dippers paid me no heed, coming and going up- and downstream unperturbed.

Not so the kingfishers, who—I soon discovered—had a nest across the creek. Kingfishers nest in burrows dug one or two yards deep (but sometime more than four yards deep!) in earthen banks, and this one was beautifully inaccessible to almost any predator. The dirt bank was vertical, and the nest entrance was well below the top of the bank and several yards above the stream. No way was I a threat, nor was anything else. But every time they arrived and discovered me on my perch, those parent birds sat in trees just upstream and glared at me for long minutes. Eventually, if I stayed very still indeed, they would go to the nest.

I don’t know if they raised their chicks successfully, because my dippers finished raising their young ones before the long chick-rearing period of the kingfishers was done. However, it is likely that they were successful, because they nested in this same bank for several years. The steep dirt bank eroded a bit almost every fall and winter, but the birds just dug a little deeper, extending the burrow, and carried on.

At the end of a nesting burrow, kingfishers excavate a nesting chamber, big enough for five or six eggs and an incubating adult and, later, for those chicks to grow to full size. The chicks stay in their chamber for about four weeks. The parents, but especially the male, feed them diligently, first on partly digested fish and then on small but whole fish. These parents typically had to fly at least half a mile downstream to find good fishing, because small fish are not abundant in the upper reaches of this creek. Long foraging flights are not unusual for these birds.

Unlike songbirds, kingfisher parents do no nest sanitation. Instead, the chicks squirt the walls of the chamber with their liquid excrement and then pound the walls above the wet spot, putting a thin layer of dirt over it. I have to wonder how that habit got started!

Most of us have seen kingfishers perched on a branch over the water or even hovering over the water surface, looking, looking, looking. And if they spot something good, then down they plunge. Most dives are shallow, not much below the surface of the water. Usually they capture fish, but they can also eat frogs, large insects, crayfish and so on.

An interesting thing happens as the diver enters the water. Think about this: if you reach down into water to grab something, you often find that the object of your reach isn’t quite where you thought it was, and you miss it by several inches. That’s because water bends the light rays more than air does and your eyes don’t compensate for the change of direction. This problem occurs when light crosses a surface between two media at an angle.

Photo by Kathy Hocker

Kingfishers face the same problem. Sighting the prey from the air only gives them an approximate locations to aim for. But their eyes (and those of other birds that pursue active prey) have a feature we don’t have. In the back of a human eye, on the retina, is a little pit (the fovea) where there is a high density of visual cells, so this is an area of very acute vision in one medium (usually air). However, these birds have not one but two foveas, separated by a little distance, and their vision shifts smoothly from one to the other as they enter the water. One fovea works primarily for lateral, monocular vision, with the line of sight directed mostly to the side, but the second one is located where the line of sight converges with that of the other eye, producing very sharp binocular vision over a wide field of view. So when the diver enters the water, the second fovea is engaged, and that gives the diving bird high visual acuity at the all-important last moment before the prey is grabbed in the bill.

I have not found much published information on the success of kingfishers in capturing prey. A study of the Amazon kingfisher (which lives in Latin America) showed that capture success ranged from eighteen to sixty-two percent of attempts, depending on circumstances. A study of our Belted Kingfisher in California found that over half of attempts were successful if the bird was hunting from a perch but only twenty percent if the bird was hovering.