The arrival of Red-winged Blackbirds is a sign of pending spring; They have now been observed in Nelson over the last week. Twice I have tried to get shots of them, but they tended to hide in the brush. The male’s spectacularly bubbly song reveals them, but pictures amongst the brush proved difficult. Today was no different — except for one spectacular flight in my direction.
When flying off some brush, a Red-winged Blackbird happened to fly towards me.
For the past few days, there have been seven Trumpeter Swans visiting the shallows to the south and west of Kokanee Creek Park. I visited them early this morning.
On their spring migration north, both swan species often stop by Kootenay Lake to feed. It works out well for them as the water level is low and dropping, which enables them to use their long necks to gain access to the aquatic plants in the shallows.
One of the curiosities often seen where swans are feeding are other ducks. This swan is accompanied by a wigeon. The attraction for the wigeon is the material that the swan stirs up as it feeds. Plant material rises to the surface and others with shorter necks gain access to it.
An adjacent family of five Trumpeters has attracted other feeders: Canada geese, Mallards, and Buffleheads.
The family of Trumpeter Swans is made up of two whitish adults and three (equally large) greyish chicks. That the chicks are still greyish is telling. Had these been Tundra Swans, the chicks would have already turned white by this time of year.
This seems to be a couple, but with no chicks.
I have saved the best two images for the last. Each was taken by my daughter, Cynthia Fraser. The first shows the spread wings of one of the three juveniles.
The second shows the spread wings of an adult.
Dipper – the eyelid flashes white when it blinks! This is so different from any other bird that it begs for an explanation.
David Sybley
A dipper has both a dark plumage and dark eyes. Why would it have evolved a white (feathered) eyelid? David Sybley is an authoritative author on birds who knows the literature, and yet he is unable to offer an explanation. Further, up until this morning, I would have accepted his aside that the dipper’s white eyelid was different from any other (dark) bird.
However this morning, I saw another bird with a dark head and dark eyes that sported a white eyelid. That second bird was a Black-billed Magpie. Both the dipper and the magpie are somewhat uncommon locally, yet, if you know where to look, they can be found.
When watching a dipper, I often see it flash its white eyelid. Until this morning, I had neither seen, nor suspected, that a magpie could do so also. The sight was so unexpected that I sought confirmation. I found no images of the magpie’s white eyelid on the web, but on the Cornell website, I read about the Black-billed Magpie:
In groups, males establish dominance … flashing their white eyelids.
Now, the magpie I saw was on its own, and so was not seeking dominance. However, the text did acknowledge the magpie’s white eyelid.
So, for what purpose has the white eyelid evolved? The mystery deepens.
A dipper blinks and displays its white feathered eyelid.
This morning’s shot of a magpie displaying its white eyelid.
Last November, I received an enquiry about dippers from the production crew of a nature film:
…it is quite surprising to see a bird which is not a penguin swimming under ice! Do you think that there are any locations where dippers frequently swim under ice?
The enquiry came about because of an essay I had written about dippers and ice. I responded with information about our local dippers, but noted:
I have never seen a dipper swim under border ice. Of course, they might have done so, but, unlike penguins (which I have watched in Antartica) this does not seem to be a behavioural characteristic of dippers. Predicating a filming mission upon dippers swimming below ice does seem to be a bit of a stretch.
And that was that.
Yesterday, I was watching a male Common Goldeneye foraging in a bay. As does the dipper (which is a songbird, not a duck), goldeneyes hunt underwater where they capture and eat, among other things, aquatic arthropods. While this male did forage in the open water of the bay, it repeatedly swam under the border ice, sometimes returning with a comestible.
I have no idea what the goldeneye found so appealing under the ice. (Maybe it was influenced by a just-watched nature film about penguins.)
The male Common Goldeneye heads across the open water of the bay and towards the border ice.
Upon reaching the ice, the duck dived under it.
Surfacing again at the ice’s edge with something in its bill, the goldeneye promptly swallowed it. The duck then foraged under the ice a few times more.
Antlers have a relentless rhythm.
HORNS: Antlers are not horns. Antlers regrow annually; horns are permanent. Antlers grow at the tips; horns grow at the base. Antlers branch; horns do not.
Over the period of a year, antlers bud, grow covered with velvet, harden and lose velvet, are used in sexual combat, repulse predators, and get discarded. This sequence is then repeated to produce a larger and more complex structure the following year.
Antlers: This posting discusses the white-tailed deer for this deer offers the most antler sightings. However, I have photographed antlers on the four less frequently seen local cervids: moose, elk, caribou, mule deer.
Yet, any observation of antlers is a matter of happenstance. Although this feature of the white-tail deer is shown here, they are only found on males, and males are not as often seen at the valley bottom, so being able to track their vagaries is chancy. Consequently, this sequence of images has been assembled using many different deer taken over multiple years.
Two white-tailed deer pause below a willow tree by the lakeshore. One, with antlers, is clearly male. At this distance, the sex of the other is unclear. Is it a female, or a male that has lost its antlers? Thus begins a exporation of antlers. (Picture courtesy of Cynthia Fraser.)
It is July and is this fawn’s first season. As yet there is no indication of the fawn’s sex and certainly no sign of antlers.
The first sign of a fawn’s antlers to come appears in early August when a dark spot turns up above and behind each eye. It is probably dried blood caused by the pedicle breaking the surface (rather like teething). The pedicle is the base from which antlers will subsequently grow.
Now in September, the fawn’s pedicles can form two buttons on the forehead, but the first antlers will not arrive until the following year.
Nothing then happens until the following April when antler buds appear.
The first year’s antler growth produces little more than simple spikes. Succeeding years produce larger and more complex structures. However, we are getting ahead of ourselves.
Extensions of the pedicles on a deer’s skull, antlers are a composite structure of bone, cartilage, fibrous tissue, skin, nerves, and blood vessels. They grow faster than any other mammalian bone for they must be grown anew each year. While they grow, they are covered with a vascular skin known as velvet, and it supplies oxygen and nutrients to the growing bone. The velvet covering makes the antlers look bulbous.
These are velvet-covered antlers in mid August. At this time the growth rate is as much as six millimetres per day. However, the velvet seems to be rather sensitive, and deer resist allowing contact with it.
It is now the end of summer. The antler has achieved its full size; the velvet is falling off and the antler’s bone hardens and dies. This dead bone structure is the mature antler, which is now ready for both combat and predator repulsion.
This pair of males at the end of August provides an interesting contrast. Although the antlers are small (perhaps second year) the buck on the left is still in velvet, while the one on the right has mature antlers. The transition is occurring.
It is apple-stealing season and a buck with mature antlers scarfs one. Alas, I have no pictures of the rut — the period of sexual combat between males for access to females. So, a picture of stealing apples will have to suffice.
We now come full circle to the initial picture of two deer under a willow tree taken at the end of January. It is antler shedding time and the deer on the right is seen to be a male that did not have a clean antler loss. They fractured as they fell off. This might have come about as the result of a pedicle or skull injury. However, it is clear that the loss of last year’s antlers is now underway. Soon the growth of new, larger, and more complex antlers will start. The beat goes on.
Each of these January images lacked a posting of its own and so is assembled here.
Hooded Mergansers show their interest in each other, even at this time of year, by raising their crests and displaying. These two pictures were taken ten seconds apart. First the male (left) displayed, and then the female responded.
A thorn-covered bush sits beside a creek in the morning. Steam fog, which formed over the creek, has drifted against the branches and lightly touched them with rime. In addition, the resulting high vapour pressure has prompted the growth of hoar frost.
A white-tailed doe stands in a field with her fawn. These deer have difficulty distinguishing stationary things. Once alerted, they stare, listen, and wonder if there really is a threat. They are both waiting to see motion before deciding to bolt.
The red of a House Finch is a result of the carotenoids it eats during its moult. Females prefer to mate with the reddest of the males.
The side of this snow-covered slope is furrowed. During the day, melt water drains to the bottom of the snow pack and runs down the slope. Following similar paths, the flow causes the snow above it to sink locally and so sculpts the hillside with tracks.
A male Pine Siskin dives.
My yard lies within the range of a few Ruffed Grouse. I don’t see them every day, but often enough that I get to track some of the species’ idiosyncrasies.
It is winter, and the Ruffed Grouse often now feeds in trees rather than on snowy ground. As the grouse is prey, its eyes are on the side of its head to give it panoramic vision to spot predators.
In this view of the back of the grouse, its protruding left eye can be seen. The grouse can actually see behind itself. Also, the unbroken dark terminal band on its collapsed tail is evidence that this bird is a male.
That this grouse is likely a female is evidenced by the dark terminal band on its spread tail. The band is broken in the middle by a greyish section. Alas, while this is suggestive of the bird’s sex, it is not definitive.
The -kins are getting together. Siskins are little finches that are partial to eating seeds. Catkins are pods of seeds hanging from some broad-leafed trees. The two are clearly kins.
Pine Siskins are with us year round. They travel in large flocks that settle on plants to eat seeds, and on winter highways to sip salt and get mashed (see bird brains).
A lone Pine Siskin uses its feet to hold a catkin still as it extracts seeds from it.
Where there is one siskin, there are dozens. These are raiding the catkins of alder birch.
OK, this Pine Siskin is not raiding catkins, but I couldn’t resist the scene.
Dipper under ice
A dipper sometimes forages under ice.
I believe I know when and why it does so.
The odd thing about this, is that I have often watched a dipper stand on the border ice along a creek, dive into the open waters in the middle, retrieve something, and bring it back to the ice to eat. But, I had never seen one dive into the water and then turn to forage under the ice it had been standing upon. Why would a dipper do this?
The insight for me started last November when Liv Grant wrote me about dippers in connection with a nature film, “it is quite surprising to see a bird which is not a penguin swimming under ice!” I responded that I had never seen a dipper do this. Then four days ago, I posted about a Common Goldeneye foraging under ice and mentioned the problem with dippers. Two observers, Derek Kite and Bob Stubbs, then wrote me separately to say they had seen a dipper forage under ice. Superb. But, what occasioned the difference between the dipper’s behaviour during their observations and my own earlier ones?
We have now had a succession of days with temperatures of between -15 °C and -10 °C. Local creeks are icy, so yesterday, I went dipper watching. This time, the dipper was seen repeatedly foraging under border ice and I realized when and why they do so.
First, there is a discussion of the dipper’s behaviour, and then an explanation of it.
A dipper stands on border ice and is about to swallow an aquatic arthropod that it had retrieved from the bottom of the creek.
The dipper stands on the edge of the border ice about to dive.
It would then dive in, but promptly turn and swim under the border ice it had been on.
Finding something under the ice, the dipper brings it to the surface and eats it. It looks rather like a caddisfly larva.
The dipper did this over and over (for as long as I was willing to watch it). Here it can be seen swimming under some really thin ice. Once I saw it travel at least two metres under the ice. It almost always found something worth retrieving and eating.
The dipper doesn’t usually forage under ice. The clue to when it does so is that there has been a succession of days with temperatures below about -10 °C, which festoons the creek with ice. Yet, this doesn’t answer the question of why it forages under ice only sometimes when there is ice. The answer to why lies with the two forms of ice found along a turbulent mountain stream. Border ice, which lies atop the water, forms along the gently flowing creek sides. Anchor ice, which lies on the base of the creek, forms in the turbulent central channel. (See a discussion of how these form.) The dipper acquires most of its eatables along the base of the creek, and the central portion of this is now covered by anchor ice. However, under the border ice, the creek’s base is clear so the hunting is good. The dipper now forages where it can find food, that is, under the border ice. In this earlier picture, the border ice is on the lower left and upper right, while the anchor ice is the yellowish material in the centre.
