Outdoor therapy

One day recently, I was feeling quite grumpy, disgusted, annoyed, and getting down-hearted, so I decided to cheer myself up by thinking about ‘a few of my favorite things’ that happened in the past couple of weeks.

On Hearthside’s annual author’s cruise, a humpback whale put on a fabulous show. She swam along a shore, pec-slapping vigorously, and then turned around and did the same coming back—sometimes flailing both pectoral fins at once. Then we saw that she had a calf alongside, and the two of them breached repeatedly. They were attended by several sea lions, who jumped and cavorted in and out of the waves created by the breaching. The show had everyone on board in a state of happy fascination.

A trip up Gold Ridge above the tram was a good one, despite the heat that had me just creeping along. The marmots were, sensibly, dozing in their cool burrows (unlike Alice falling down a rabbit hole, I did not fit the burrow entrances—too many cookies, perhaps?). Bumblebees were busy, attending to the tiny blossoms of alpine blueberry growing close to the ground in a tight mat. The alpine zone was a sea of flowers (I counted over twenty kinds, including one that was a complete mystery to me). An American pipit perched on a hot rock, overseeing his nesting territory of alpine tundra and rocky outcrops. Two male rock ptarmigan showed off their brilliant white plumage in soaring flight displays from one rocky tower to another, cackling all the way—still looking for ready females. As the afternoon breezes picked up, ravens began to play in the air currents, sharing air space with hang gliders.

One day I sauntered around some muskegs with a friend, just seeing what we could see (a most enjoyable occupation!). Even though the ponds were mostly dried up, a few held some stubborn water striders, and the mud held evidence of the passage of jays, squirrels, mice, and other small beasts. We noticed a fly bearing an irregular yellow patch on its back, perhaps pollen from a floral visit. It found another fly, which obligingly spread its wings and allowed the first fly—now clearly a male—access to her rear end. They copulated for several minutes; through his beautiful, translucent blue abdomen, we could see his internal organs moving. Together they moved around in the low vegetation; eventually she brushed him off under a twig.

The beavers seem to have returned to Steep Creek, after an absence of several years. We had seen beavers visiting the lower ponds, but this time it looks more serious. The broken dams have been rebuilt and a friend watched a beaver collect a huge mouthful of grass and carry it toward the old lodge. This made me wonder if the grass might be bedding for a young family. There is hope, then, that the beavers may restore the upper dams as well, creating ponds that trap sediment, provide fine rearing habitat for juvenile coho and Dolly Varden, and good foraging habitat for birds. In the past, the sockeye and coho salmon that spawn in this stream proved themselves quite able to surmount the previous dams, and there were good populations of both species in the creek.

The rains came! Not, this time, a source of gloom but of gladness! May was a drought month in Juneau, with very high temperatures on several days. Muskeg ponds dried up, lichens and mosses got crispy, and streams turned into trickles. But the soft rains in early June brought lower temperatures and turned Juneau into its usual lush, verdant self; the creeks flowed again. (And now we are ready for some more sun!)

There, that’s a list of good things observed. Thinking about all that, I found that I was still grumpy, disgusted, and annoyed—oh yes—but it no longer got me down-hearted. Good stuff!—simple things for a simple mind, maybe, but equanimity was restored!

Advertisement

Winter white, summer brown

This winter I’m seeing snowshoe hare tracks very commonly, in a variety of locations. Sometimes, repeated travels created well-packed hare highways through the brush. But I certainly don’t see the track makers very often, perhaps partly because I’m not out there at the times that they are most active. Another reason is that they are usually quite well camouflaged, with white fur in winter and brown fur in summer. Sometimes, however, the timing of the molt is not in synchrony with the background colors of the environment, and there’s a serious mismatch between hare and background: the hares become quite conspicuous as white patches on brown background or brown patches on white background.

There are at least ten mammal species in North America that show this kind of seasonal coat-color change, as well as some in Eurasia. In Alaska, we have the snowshoe hare, the Alaska hare, the short-tailed weasel or ermine, the least weasel, a species of collared lemming, and the Arctic fox. The ermine and snowshoe hare are the only ones in Southeast. Some of these species have large geographic ranges extending southward, where snow is less common, and the change to white doesn’t happen there; in contrast, hares in the Canadian High Arctic may not change to brown. In some cases, there is variation among individuals within a single population, some showing the seasonal change and others not. The general consensus seems to be that the observed coat-color changes are adaptive principally in providing seasonally appropriate camouflage and protection from visually hunting predators. Winter coats are often thicker and better insulated as well, but apparently the color itself does not greatly affect heat gain or loss.

As far as I can determine, in all species in which this has been studied, the physiological control of the coat-color change is driven mainly by photoperiod, or the relative lengths of day and night during a twenty-four-hour period, mediated of course by hormones. So if climate change brings less snow, but the physiological control of color change is still regulated by day length, there can be some serious mismatches between coat color and background. Seasonal timing may differ slightly for males and females, and for breeding animals vs nonbreeders. In some cases, temperature is thought to have a modifying effect: warm temperatures in fall, for example, may delay the molt somewhat, or hasten it in spring, but this effect is generally less than that of photoperiod.

In the bird world, ptarmigan engage in seasonal shifts from brown plumage in summer to white plumage in winter, and back again. Here too, the principal driver of change is photoperiod, and there can be timing differences between male and female. For example, willow ptarmigan females get their brown summer plumage earlier than males.

The most intriguing species is the rock ptarmigan. Males sport a showy white plumage in spring, for weeks after the snow has melted and their females have molted to a cryptic brown (which makes them very inconspicuous while incubating eggs in the nest). Males keep their conspicuous white coat until well after their female consorts have laid eggs and are no longer fertile. However, when egg-laying is underway, the males do something very unusual: they start to make their white plumage dirty, and by the time egg-laying is complete, they are very dirty—and much less conspicuous– indeed. But if the clutch of eggs is destroyed by a predator, or if the female is killed, suddenly the bereft males clean their plumage to a brilliant white again, and go a-courting once more. Most rock ptarmigan mate monogamously, but a few males are polygynous (with more than one female) and some may not obtain mates in any given year. The bachelors and polygynous males stay clean white longer than monogamous males, in keeping with their protracted potential for mating. Eventually, all the males turn brown, until it is time to turn white for the next winter.

Male and female rock ptarmigan in spring. Photo by Bob Armstrong

The rock ptarmigan use the seasonal pattern of plumage change for camouflage, like all the other animals that do the white/brown shift. But in addition, the males apparently use their white winter plumage as a sexual advertisement in spring and early summer, and female rock ptarmigan choose their males in part on the basis of this studly self-advertisement. There is no doubt a cost to showing off this way; rock ptarmigan suffer heavy predation, and those studly, conspicuous males are taking risks and paying a price.