March goulash

 

March closes with a handful of birds that just did not make the cut to have a posting of their own.

The first sightings of the Eurasian Collared Dove locally were made in 2008 after they had spread across the continent from a 1970s introduction to the Bahamas. The bird is now fairly common around the Creston Flats.
 

The Dark-eyed Junco is quite common in the spring as many move north to breed. This one was singing.

How does one lose a flock of swans? These were flying along the West Arm, but I couldn’t find their destination.

Had I not seen a Red-tailed Hawk fly to this tree, I would have never spotted it in the foliage.
 

On March 30th, a Tree Swallow arrived at pilings it previously used for nesting, but there it found a flicker. Of a group of three cavities suitable for the swallow, two already held flickers and one is being explored by starlings. It will be interesting to see how this plays out.

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Bluebirds and shrike

 

Yesterday I watched insectivores hunting in a field: Mountain Bluebirds and Northern Shrikes.

Two weeks ago, the treat was the Western Bluebird, which sports an orange breast and shoulders. The breast of the Mountain Bluebird is powder blue (male) or grey (female).

A male (left) Mountain Bluebird and female (right) watch for insects from a fence.

From such a perch each will swoop down and capture a bug.

Unexpected was a sight of Mountain Bluebirds and a Shrike on adjacent fence posts. While they all hunt insects, the shrike will also take small birds. Indeed, the bluebirds seem to be eyeing the shrike warily. 

I managed to get close enough to get a couple of portraits. First the (male) Mountain Bluebird,

then the Northern Shrike.
    

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Disparate grazers

 

On adjacent days I watched two rather different mammals graze: marmot and elk. The two occupy different habitats and differ in weight by a factor of a hundred, but for each, grass is a staple of its diet.

A Yellow-bellied Marmot eats grass during the day along the edge of its home in a field of rocks.

An Elk eats grass during the evening in an open field.

Each deserves a portrait set in its favoured habitat. First the marmot,

then the elk.
  

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Pole dancer

 

While she gyrated, the male Mallard watched from the beach.

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Shore-facing cavities

 

Yesterday, as I watched a flicker couple excavate yet-another cavity nest on the shore side of a piling, I speculated that there might be an interesting story to be told. 

Over the years I had casually been aware that the cavity nests that the Northern Flicker constructed in pilings around Kootenay Lake seemed to follow a pattern: They all seemed to face the shore. But, would my anecdotal observations hold up to the collection of a few more observations? And if they did, what might be motivating the flickers to do this?

Elsewhere, Northern Flickers build their nests in trees, and, as Karen Wiebe noted in a 2001 paper about the flickers at Riske Creek (southwest of Williams Lake, BC), flickers tend to orientate their cavities to the south—apparently to increase the incubation temperature. Yet, that pattern, seen in the Cariboo, did not seem to hold around here. 

This morning I did a casual survey of (some easily accessible) pilings around the West Arm of Kootenay Lake looking at shorelines oriented in various directions. Where the shoreline was west of the piling, the cavities faced west; when shoreline was north of the piling, the cavities faced north; when north east, they faced that way. It was the same for south and south east. There was no preferred compass direction, certainly none dictated by the Sun. The shoreline dictated orientation. 

At first, there appeared to be two puzzling exceptions to this pattern: pilings on either side of a narrows (a constriction in the Lake), and those adjacent to a floating drydock. In these cases, cavities appeared on each side of the pilings. Yet, these make sense. If the objective is to face the shore, then in a narrows, there is an ambiguity as to which shoreline is relevant. Some of the cavities on the pilings holding the drydock faced the shore, while others faced the dock. However, from the bird’s point of view, the dock was probably perceived as merely another shore.

Now comes the first speculation: The flicker’s concern is for a land predator. It is better to see one coming and be able to vacate than to have one attack from behind. (An aerial predator could come from any direction, so there is no preferred defence there.) 

A second speculation: When flicker chicks fledge, it is better to have them fly towards land than out over water.

But, why does the Kootenay Lake experience differ so much from that of Riske Creek. Possibly because on land, a predator can come from any side so optimization might as well be based merely upon incubation temperature, and a chick can fledge in any direction.

 Yesterday’s (female) Northern Flicker. She was building a nest on the north side—the shore side—of a piling.

This is a view of last year’s flicker couple checking out a shore-facing nest. In it, they later produced chicks.

The wooden pilings holding this floating drydock contain flicker cavities that face both the shore (to the lower right) and the dock. From the flicker’s point of view, the dock is probably just another shore.

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Tug Hosmer

 

Following last week’s low-water visit to the wreck of the sternwheeler, Kuskanook, another relic of the steam age was visited: the tug Hosmer. The history of this large steam tug is told on Living Landscapes, which also presents a nearly twenty-year-old map of the wreckage.

The wreckage lies in the shallows between Bealby’s and Horlick’s Points a bit east of Nelson. The boiler is seen in the centre. Forward of this (to the right in the picture), the hull has collapsed outward away from the stem piece (which sticks out of the water).

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March marmot

 

Around here, the Yellow-bellied Marmot emerges from hibernation in the latter half of March (2012, 2013, 2014). Yesterday’s marmot is having grass for breakfast after its long winter’s nap.

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Red-tailed Hawk

 

A week ago, when I posted flying raptors, I included a mediocre shot of a Red-tailed Hawk merely to complete the set of raptors seen that day.

Contrast that with the three shots of a Red-tailed Hawk, below. This bird was recorded en passant while I was up to something else. Nature does not dance to tunes I play. 

“Why are you watching me?”

“OK, I’m outta here.”

“Yet, I am sufficiently curious that I will watch you from above.”

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IR snow melt

 

Today, I noticed an interesting variant on a familiar pattern while walking along the beach: snow distribution sculpted by infrared radiation. An unexpected dusting of snow overnight had set the stage for the patterns.

Most people spend little time thinking about infrared radiation (IR), yet it is all around us. Everything emits in the IR by an amount (almost entirely) determined by its temperature. Rocks emit, trees emit, clouds emit, people emit. The warmer the object, the more energy is emitted. 

Similarly, everything absorbs IR radiation from the things in its line of sight. So, an object loses energy based on its temperature, but gains based on what it receives from its surroundings. Whether an object’s temperature rises or falls depends on whether it gains more than it loses, or vice versa. 

Consider the ground at night (so, we are not dealing with sunlight). If the ground temperature is, say 10C and the (effective) sky temperature is -20C, the ground will emit more IR radiation than it absorbs from the sky and so it will will cool: the ground temperature will drop.

That is assuming the ground has a clear (hemispheric) view of the sky, either because the surface is flat, or we are on the top of a ridge. But, what if we are dealing with the ground in a valley? The valley bottom will see only a portion of the colder sky, but also a portion of the warmer valley walls. It will end up warmer than the ridges owing to it also receiving from the warmer valley walls. 

The first two pictures were posted three-and-a-half years ago as beach frost. They serve to set the stage for the last picture which was taken today.

That overnight, the footprint ridges have become cooler than the valleys is clear from the distribution of dew.

The same is true of frost: it forms preferentially on the colder ridges. Of course, unlike dew which darkens the sand, the frost makes the ridges appear lighter.
 

In the previous two pictures, the variation of temperature from ridge to valley determined where condensation took place. In the picture, below, it determines where melting takes place. A dusting of snow had covered the whole beach, but it melted first in the warmer valleys caused by footprints.

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Anniversary bluebirds

 

Today marks the tenth anniversary of this website. It was launched on March 15th, 2005.  

The original, and abiding, objective of the site was neither commercial nor promotional. It was merely a notebook of things learned about my surroundings. Had someone else built such a website, I would have been content to learn from it. No one else did, so I set to work. 

Ten years later, the website and its blog receive about seventy-thousand page viewings a year. Most visitors are from Western Canada, but many come from other provinces and lands. Such numbers are small potatoes in the modern world of febrile social media. For me, relative obscurity is good: I am not a populist, but a backwater naturalist consulting his muse. 

Yet, a decade does represent a satisfying anniversary for the project. How should it be marked? I thought about a reprise of favourite images, but decided that it would be more fun to just press on. 

Fortunately, an observation this last week provided the ideal subject material, the Western Bluebird. (Thank you, Darcy Samulak for showing me where to find it.)

Locally, we encounter two species of the beauteous bluebird. I had seen the Mountain Bluebird other years (Puffed blue, Bluebird of unhappiness), but had not seen the Western Bluebird until last week. Unlike the Mountain, with its powder-blue breast, the Western has an orange breast and shoulders. The male’s colours are bright; the female’s are muted.

What a grand present: an anniversary bluebird.

The male Western Bluebird has a blue head and wings, but an orange breast and shoulders.

He is seen chasing some unsuspecting insect.

The female has muted colours.

She is seen here pouncing on and then wrestling with a larva.

Seen from the back, the male is strikingly ultramarine blue, sometimes with touches of orange.

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