Muskrat food


Last Saturday, I spoke at a symposium and showed many portraits of local creatures. I noted that the muskrat, the smallest of our three semi-aquatic mammals, is often unjustly maligned. It is not actually a rat, but an aquatic vole, and substantially a vegetarian that feeds on aquatic weed. 

I did a bit of digging to see if I could discover why this little creature gets demonized. Apart from the misconception that it is a rat, it seems that farmers don’t like that it burrows into pond banks and dock owners don’t like that it gnaws on some materials used for floatation. These rather narrow concerns don’t impress me. I like muskrats.

A muskrat swims back to its den with a mouthful of aquatic weed. You go, muskrat!

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Pushing off


One’s reaction time — typically about 0.2 seconds — isn’t small enough to photograph some fleeting events: once something interesting is seen, the press of a camera button always comes too late to record it. Inevitably, some pictures are little more than mistakes where an attempt to capture one thing results in another.

The instant a dipper pushed off was an inadvertent, if delightful, capture.

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Sunny crossing


Yesterday, I had occasion to cross Kootenay Lake on the M.V. Balfour on one of the few sunny days in the last few weeks. It offered the opportunity to take a couple of panoramas.

The first view is a scene as the ferry is pulling out of Kootenay Landing in the late afternoon. The route will take one across the Lake to the gap in the mountains and the low sun. To see right around the horizon, click down on the panorama and drag in either direction.

The second view was taken as the ferry was entering the narrows between Balfour (the town) and Procter. This (polar stereographic) mapping has been given the cute name of the little planet. The fall foliage of cottonwoods along the shore and larch higher on the mountains adds colour.

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Snow Goose


Snow Geese are an uncommon sight around Kootenay Lake. 

A year ago, when I saw one (Snow Goose), I suspected that the juvenile I saw had wandered far off its coastal migratory course to have ended up here. That is probably also true of yesterday’s juvenile Snow Goose, a bird that I would have missed had not Paul Prappas told me that there was one hanging out in a field near my home.

Snow Geese usually travel in huge flocks. This local juvenile was alone.

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The rains this October have offered few opportunities to wander about. These same conditions may have impeded the movement of some birds, which could account for yesterday’s late-season observation of a Western Meadowlark. 

The meadowlark is a grasslands species that forages on the ground for insects and seeds. So, it is not surprising that sightings are uncommon in our mountainous and heavily forested region. It is usually seen around May when it passes through the region to breed farther northwest. Starting in August, meadowlarks head south again. 

It was unexpected to see some between showers yesterday (late October), especially as they were foraging in a forest alongside a mountain road.

This Western Meadowlark, seen in May, is included merely to show the bird in its breeding plumage.

The meadowlark seen yesterday in a forest high above the Lake is in its muted non-breeding plumage.

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23 cm/s


Katabatic wind: a usually gentle wind of cool air that drains down the mountain slope overnight. When the sun warms the slope and the air above it, a katabatic wind usually stops.

Yestermorn, I was watching the languid drift of steam fog as it was carried offshore by a gentle katabatic wind. On other occasions, I had seen ripples on the water caused by the passage of a katabatic wind, but on this occasion, although there were tiny waves flowing towards the shore from off the Lake, the katabatic wind passed over the water without leaving a trace. If the drifting steam fog hadn’t revealed its passage, I wouldn’t have known there was a wind at all. How can a wind travel over the water without disturbing it? (Continued below the first picture.)

Even though a wind was carrying steam fog across the water, no water waves revealed its passage.


Suddenly, the lightbulb went on. I knew that everything that moves across the surface of water makes waves — well, everything that moves faster than 23 centimetres per second. I already knew that if a bug, such as a whirligig beetle or a water strider, moves very slowly across the water it makes no waves and so avoids both wave resistance and revealing itself to prey through spreading waves. Now, it seems, I can add a gentle katabatic wind to the things that can move over a water surface and neither make waves nor encounter wave resistance.

For there to be a water wave, there must be a force that restores the position of the water that has been disturbed by, say, wind, boat, or swimming animal. If the wavelengths are longer than 1.7 cm, the dominant restoring force is gravity; less than 1.7 cm, it is the surface tension of water. These really short waves are sometimes called capillary waves, but more often they get the name ripples.

The odd thing is that the two types of waves behave differently: the fastest ripples are the shortest ones; the fastest gravity waves are the longest ones. A wavelength of 1.7 cm has a wave speed of 23 cm/s, which is both the slowest ripple and the slowest (gravity) wave. All other waves move faster than 23 cm/s. So a bug or wind moving across the water at a lower speed cannot excite waves.

Gentle breeze: If 23 cm/s (0.23 m/s, 0.8 km/hr, or .5 mph) is the transition speed, just how slow is it? It is about a quarter or a fifth of a typical adult walking speed — a baby crawl.

This seemingly esoteric and curious fact has easily observable consequences, as will be seen.

As a katabatic wind flows down the mountain slope, it is slowed at the surface by the friction of passing over trees and rocks. Assuming it is moving at less than 23 cm/s when it reaches the Lake, it does not disturb the water. However, this lack of wave resistance also means that the drainage wind now begins to accelerate. A short distance offshore, the wind is moving faster than 23 cm/s and now it begins to make waves.

There are katabatic winds on the Lake in this sunrise scene taken a month and a half ago. Disturbed water can be seen in the image below. Katabatic winds have descended the slope on the shady (cool) left side of the picture and have spread over the water. They are also apparent on portions of the right side still in shade, but where the sun has warmed the slope, the winds have ceased. On the left side there is often a gap between the shore and the disturbed water. While there is a wind there, the air is moving at less than 23 cm/s. However, the lack of resistance to the flow allows it to accelerate above the transition speed and start disturbing the water farther offshore with waves.

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Three waterbirds


A brief break in the rain allowed a few sightings.

I usually avoid showing wildlife among human devices. However, Double-crested Cormorants are not all that common locally so these ones deserve to be recorded.

A Common Loon in its non-breeding plumage seems to be auditioning as a fountain.

While a Pied-billed Grebe is a welcome sight, here it is water reflections that catch the eye.

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Merganser eats


Most waterbirds that eat fish, swallow it whole: Great Blue Heron, Common Merganser, Horned Grebe, Pied-billed Grebe, Common Loon, Belted Kingfisher. These birds lack the ability to hold a fish with claws, tear it apart, and eat it piece by piece, as would an Osprey or a Bald Eagle.

So, how does it happen that the female Common Merganser, below, is downing only a piece of a fish? The answer is simple, she was hunting in a spawning creek which contained not only complete fish, but also fragments that had been torn apart by other birds and mammals.

A female Common Merganser is about to down a fish fragment.

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Black grizzlies


When I saw black grizzly bears three years ago, I was puzzled for I hadn’t realized that black was even an option for grizzlies. It is, but a somewhat uncommon one. When a black grizzly family was seen this week, it was only about three hundred metres from where the earlier family had been seen.

A family of black grizzly bears was foraging for kokanee salmon in a stream.

The sow eyed an intruder suspiciously.

She sent her cubs towards the woods.

When she stood to get a better look, she provided me with a calendar-ready picture. 

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Parking attendants


A black-bear sow and her cub often sleep the night in a Douglas-fir tree about sixteen metres above a local parking lot. Folks who arrive at the lot in the morning refer to them as their parking-lot attendants. Indeed as a car arrives, the bears will often open a bleary eye as if trying to monitor the lot’s usage.

After briefly peeking at an arriving car, the sow and her cub have drifted off again.

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