The varied water birds seen at Nelson’s winter waterfront continue to impress. This season I have shown swans, coots, goldeneyes and scaups. Here are three more species recorded today.
Mr. and Mrs. Hooded Merganser swim past.
This is one of a number of Redhead Ducks seen during a snow shower.
Finally, an adult Great Blue Heron was seen resting on the broken pilings of the old C.P.R. dock.
Blossoms: This posting is just about white on trees resulting from water. Blossoms and seeds are another matter.
Following the reaction to my posting about a rime band, I thought it might be worthwhile to offer a guide to some sources of whiteness on trees.
Of course, the most obvious source of whiteness on trees is snow. When close at hand, snow is fairly distinctive (Jan. 1, 2012). However, when seen from a distance the assessment that the whiteness results from snow becomes less obvious — there are other possibilities.
Snow that falls on a mountainside will often fall right through the melting level and turn to rain below (Dec. 10, 2015). However all the snow does not melt at the same rate.
As the snow falls into air that has a temperature above 0 °C, the smallest crystals melt first, while the larger ones survive longer to fall farther. The result is that the bottom of the white is diffuse. The whiteness gradually tapers from extensive to nothing, without providing a sharp boundary in between (Dec. 13, 2015). So, the clue that we are seeing snow on the distant trees when the valley bottom is above 0 °C, is that the base of the white is tapered.
What then is one to make of the sight of a sharp lower boundary? This obviously did not result from snow falling through the melting level. This is the result of rime. A cloud of supercooled water droplets (T < 0 °C) had been resting against the mountain. As the droplets collided with the branches, they froze to cover the trees with rime. The sharp base results from the transition of the droplets from above the melting level to those below it (Nov. 26, 2005).
The sharp lower boundary of the whiteness in this picture of rime probably did not result from the bottom of the cloud, but rather from the presence of the melting level. But, this rime shows a sharp upper boundary also, and it will have resulted from the cloud top. The result is a band of rime across the mountain (Nov. 29, 2013).
Often when the temperature is low, there will be steam fog rising from the open water of local creeks. Then the trees alongside the creek can be covered with rime as the supercooled fog droplets collide and collect on them.
Now for something completely different. This is a picture of the sylvanshine, and although it looks to be a picture of snow-covered trees in the winter, it is actually retroreflection from dew-covered trees in the summertime when seen with a spotlight or the headlights of a car. Only a few species of trees can do this — those which have leaves (needles) that have a rather large contact angle with water. The effect is similar to that of retroreflective glass-beaded highway signs.
In this season, snow is seen that falls on the mountainside. Yet, all the white on distant trees need not be snow — sometimes what is seen is rime.
When snow falls from a cloud above the mountain, it spreads from the mountain top down to the melting level where it gradually diminishes. It thus presents a white mountaintop with a somewhat indistinct base.
What is one to make of a isolated white line across the mountainside? This is a result of rime from a shallow cloud.
Normally a cloud is filled with liquid droplets even when the temperature is well below 0 °C: the droplets are supercooled. They remain liquid at sub-zero temperatures. But, when the drops collide with objects, such as trees, they instantly freeze to produce rime on those trees.
A thin cloud of super-cooled water droplets had rested against a mountainside. As the droplets collided with the trees, they froze to produce a band of rime across the slope.
As the cloud extended along the whole mountain range, so did the band of rime.
This is a collection of images from this December, none of which has had a posting of its own.
A Coyote hunts for voles in a field.
Each winter, Nelson’s waterfront plays host to a variety of interesting water birds. Already having received postings have been coots and Barrow’s Goldeneyes. Here are four Greater Scaups. The males have black heads, the females, brown.
This is a view of border ice as seen from the bank of a creek. The circular patches are methane bubbles that have formed as a consequence of dead organic material having first settled on the stream bottom. Then bacterial decomposition released methane, which rose as bubbles, but became trapped under the ice.
A bighorn ram curls his upper lip back in the flehmen response. This gives him an enhanced ability to detect the pheromones of ewes in oestrus. Apparently, he hopes that the rut is still on.
For a while centred on 2017, this region experienced many hares. Hare populations are notoriously cyclic and by 2019 the visibility of hares had plummeted. However, all the hares have apparently not vanished, as is evident when a fresh snowfall reveals their tracks.
A dipper flies underwater as it forages for Kokanee eggs and aquatic arthropods on the creek bed.
Nicknamed for being leucistic, Lucy (Goosey) was spotted earlier this month for the first time in a half-dozen years. Seen again at the month’s end, she is apparently now hanging about nearby.
The final picture is here merely for the fun of it. It is a Common Merganser that has just lifted its head after scanning underwater for fish. That it is a juvenile is evident by the yellow eye and white patch between bill and eye.
This has been a good winter for seeing swans. However, by Christmas Eve, I had not seen any for nearly a month. Then four swans came a-visiting.
A family of Trumpeter Swans appeared at Kokanee Creek Park. The grey ones are the juveniles.
On Christmas morning, they were feeding at the mouth of the creek.
Then there were four swans a-swimming.
Comprehensive digital records from ebird.org show that the Ruffed Grouse can be seen in this area year round. My own records say otherwise.
When I look at the dated pictures I have taken in my yard, there is a conspicuous gap in the warmer months. Mind you, my yard pictures are taken at the valley bottom, while ebird treats all altitudes. (This is a mountainous region.)
There is information here about the behaviour of the Ruffed Grouse: The bird seems to head to the uplands in the warm months and return to the valleys when the snow falls (I have not seen this behaviour discussed anywhere).
It is December and a Ruffed Grouse reappeared in my yard. I expect to see it and its kin for maybe another six months before they head to the uplands again.
“Surely you don’t think that I can forage in winter without getting a little bit of snow on my snout.”
We have all seen them: star-like patterns of melt on the shallow ice of bays.
With any luck, this posting will be followed by one with more information on these so-called lake stars, for much of their formation remains a mystery to me.
Over the years of casually noting lake stars, I had just assumed that they were the result of the drainage of surface melt water back through a hole in the ice. Evidence is accumulating that this is backwards. Here is what seems to be the consensus of the few who have explored the patterns.
• a new thin (a few centimetres) layer of ice forms over stratified water
• atop the ice, it is important that a thin layer of snow has fallen
• a small hole forms in the ice (Why does it form?)
• while the lake water immediately below the ice is at 0 °C, below that, it is warmer
• capillary action causes some warmer water to wick upwards onto the snow
• this arrived water depresses the ice surface increasing the flow of water
• arrival of increasingly warm water from below increases the melting
The formation of the arms of the star remain a mystery for me. However, what I had not realized is that the flow of water is up, not down. The snow atop the ice is a necessary feature because it serves to wick the lake water onto the surface. The wicking is important as it can bring up the warmer water from below, whereas buoyancy would not do so. (Water is densest at 4 °C so the warmer denser water lies a bit below the surface.) It also remains unclear to me why the lake stars form at some places but not others.
A common, but mysterious lake star forms in thin snow-covered ice on water.
I spent a few hours rambling among raptors. While many were seen perched, this posting favours raptors seen flying.
We have two resident falcons, each of which was seen. This is the smaller; it is a male kestrel.
Slightly larger than the kestrel is the Merlin. It did fly, but I missed it.
The largest raptor seen was the Bald Eagle.
I managed no particularly good shots of a flying Rough-legged Hawk. This one will have to suffice.
However, when perched, this same female rough-legged posed for me.
This is a bit of an oddity. I believe it to be a dark-morph Red-tailed Hawk. Across the continent, the plumage of this bird is highly variable, although the dark morph is uncommon here.
My favourite flight shot of the ramble was of the more common local form of Red-tailed Hawk. This is a juvenile bird: the red of its tail has yet to develop and its eyes are yellow.
The first time I saw a Wild Turkey in a tree was only a month ago. While they do roost in trees overnight, and some subscribers commented that they see them there regularly, I had only seen these birds when they were foraging on the ground.
However, this last weekend I happened upon many turkeys flying in and out of trees.
Three are seen here.
One turkey was off on its own.
It had spectacularly spread its wings and tail while flying in.
