Tracks and king eiders

winter sightings and mysteries

Early March brought us a lot of gray skies, but there was one spectacularly sunny day when there was deep, fresh snow at Eaglecrest. The parking lot was jammed, the slopes were thronged with down-hillers, but the nicely groomed lower Nordic loop was little used by humans, at least the morning I was there.

So a friend and I ambled around the loop on snowshoes, looking for tracks and hoping (in vain) to hear an early junco singing. There were a few deer and hare tracks, and a probable mouse. A raven had landed, punching deep in the snow and bracing a bit with one wing tip; then it walked a few feet and took off again—I wondered why it chose that particular spot. Here’s where an ermine dashed out from under a bush, bounded over the snow, and dove under the deep snow blanket. Oh look! Lots of bipedal three-toed tracks circling one blueberry bush after another… clearly a grouse or ptarmigan had come for lunch, nipping dozens of tiny buds off the blueberry twigs.

Just as we were about to move on from the bud-feeding area, we saw a small shrub at the side of the trail, poking up out of soft snow: a single stem with just a few twigs on top. Suddenly it quivered very noticeably, and then did it again. That movement was not caused by wind or a falling clump of snow or anything else detectable on the surface. So I suspect that some small critter under the snow was jostling the base of the stem. A lot goes on down there that we don’t see.

The next day was gray again. I made a quick trip to Point Louisa with another friend. I wasn’t expecting to see very much, because the tide was way out. But when we got out on the point, a gaggle of bird watchers had gathered, drawn by reports that some king eiders were seen there. The watchers were what I call ‘real birders’, who keep up on recent sightings and often carry telescopes as well as binoculars and don’t need to consult the field guides to know what birds they are seeing.

Just off-shore was a big crowd of scoters that even I could identify, along with a few harlequin ducks and goldeneyes. The birders assured me that mixed in with that lot were two female king eiders and even graciously loaned me the use of a telescope. After lots of finger-pointing and information on just where in that big flock I should look, I think I finally saw them—two brownish ducks with smaller bills than those of the scoters. A first, for me!

Photo by Kerry Howard

King eiders nest on the coastal tundra way up north, with the males then in their colorful breeding dress. There they feed on invertebrates in the freshwater ponds. Most of the birds that nest up there spend the winter in the Bering Sea, where they dive for benthic invertebrates.

However, some of them wander down our way at times. In addition to some records from Gustavus, there are records, over several years, of sightings from Sandy Beach to Eagle Beach—that stretch of coast is, of course, where most of the local birders are active; it seems likely that the eiders occur sporadically up and down the coast. Most of the sightings have been in winter and early spring. I have to wonder what brings them to our area…

The birds in the big flock were bobbing about peaceably (https://vimeo.com/520231569). The scoters were diving and coming up with prey, usually a mussel. When a scoter surfaced with prey in its bill, it shook its head with the prey securely clamped in the bill, perhaps to jettison some indigestible bits and extra water. Meanwhile, the eiders were cruising around among the scoters, occasionally dipping down to grab things not far below the surface. I suspect that all those paddling feet and diving birds stirred up small invertebrates, making them more accessible to the eiders. Perhaps the eiders also occasionally snatched up edible fragments that were accidentally discarded by the scoters.

Thanks to Doug Woodby and Mary Hausler for the loan of their telescope and guidance on where to look, and to Gus van Vliet for helpful consultations. Thanks also to Kerry Howard for the photo and to Bob Armstrong for the video.

Snowy blankets

life in the subnivean world

Snow makes a great blanket (albeit damp and cool), insulating whatever lies below it from cold air above. As we found out not long ago, a few inches of snow kept solid (walkable) ice from forming on ponds, even after many days of single-digit temperatures.

Lots of critters make use of the snow. Ravens roll and toboggan; otters slide. Red squirrels often make winter nests in and under their snow-covered middens. Marten, the most arboreal of the weasel family, find winter resting places under the snow. They often use places where fallen branches and stumps intercept snowfall, creating spaces for resting as well as easier access to subnivean prey. They are reported to rest frequently in red squirrel middens, including those occupied by squirrels. Even birds find shelter under snowy blankets. Ptarmigan make burrows for night-time shelter, leaving little piles of fecal pellets in depressions, which we find in spring as the snow melts from the top of the burrow. Redpolls cluster together in tunnels under the snow to keep warm.

A lot goes on underneath the snows. Invertebrates of many kinds live in subnivean places. There are springtails, beetles and other insects, and spiders, some of them dormant, some of them active at least periodically. They are prey for shrews (which have to eat every few hours) and mice.

Keen’s mouse (the coastal form of the deer mouse) makes snow-blanketed nests in crevices or shallow burrows or cavities in logs and stumps. They often have short periods of torpor, to conserve energy, and make small caches of seeds. Unlike voles, they commonly come above the snow when foraging.

Voles and shrews scuttle along their tunnels, sometimes pursued by voracious weasels (ermine in much of Alaska and least weasel in the interior) that fit easily into those tunnels. Their nests are typically balls of vegetation with a cozy cavity, occasionally appropriated by a weasel that consumed the nest-maker. Meadow voles may even breed in winter if the snow blanket is thick and the food supply is good, but their mortality can be extremely high if the snow cover thins or their nests get wet. Many kinds of voles make winter food caches of roots and seeds and shrews often store prey for later eating.

Lemmings stay active all winter. Brown lemmings harvest the bases of grasses and sedges, as well as a lot of moss (an unusual food, not very digestible). Winter nests under the snow are thick-walled and often lined with their molted fur. The northern collared lemming makes long snow tunnels on the tundra in winter; snow burrows have nest chambers and separate latrines. The winter diet includes lots of low-growing willow bark and buds, reachable under the snow. They may even breed in winter, if the snow cover is really deep. The widespread northern bog lemming is the only lemming in Southeast, living in sphagnum bogs and other habitats. It makes nests and burrows under the snow, but little is known about its ecology.

Pikas are small relatives of hares that customarily live on rocky mountain slopes with nearby meadows. There are two species in North America, one in the Rockies and Cascades, and the collared pika in Interior Alaska and Yukon. All summer long they industriously gather grasses and herbs from the meadows to make hay piles in the rocky talus slopes; each pika may collect over twenty kilos of hay, making many trips per hour. Each pika defends a territory from other pikas and thus protects its haystacks. Most of the winter is spent under the snow, in burrows and crevices, living off the stored hay. Pikas are well adapted to cold but are very sensitive to heat; on hot summer days they hide in the rocks. Warming climate is a serious threat to their populations. In the southern Yukon, average temperatures have risen about two degrees C per decade since the 1960s, and the warming trend has already reduced pika numbers in some areas by ninety percent. There is no place for them to go: they can’t just move higher on the mountains since they are already there, and they can’t cross the warm valleys between the mountains.

Loss of snow cover is just one of the many well-documented deleterious effects of human-generated climate warming.