Exploring Kootenay Lake

Great Grey Owl: This is the fourth of five postings on this largest owl.

The Great Grey Owl flies over the meadow to catch and eat voles.

It was noted earlier that the Great Grey Owl flies very quietly. The question is: does the owl fly quietly so that the vole will not hear it coming, or, so that the owl can hear the vole’s low-frequency scratching above the noise of its own wings? Research has revealed that it is the latter <https://www.allaboutbirds.org/news/to-catch-voles-under-the-snow-great-gray-owls-must-overcome-an-acoustic-mirage/>. The vole cannot hear the owl anyway, but the owl must fly quietly to be able to accurately find the sound the vole makes.

But, what enables it to fly so quietly? A number of things contribute starting with its particularly large wings which reduces the need for rapid, noisy wing flapping that is characteristic of many other birds. And the leading edges of its wing feathers have serrations that reduce the size of the fluctuations that would otherwise create a swooshing sound. These fluctuations are further reduced by a velvety texture on the wings and body, plus a soft fringe on a wing’s trailing edge. Together, they greatly dampen its sound.

The Great Grey can hear the vole’s scratching at a distance and this prompts it to leave its perch. At first, it finds it hard to determine the vole’s exact location, but as it flies closer, detection positioning improves. In the end, the owl often hovers over the spot to accurately pinpoint the sound. It then strikes from directly above.

The owl not only hunts for voles from a perch, it also hunts by making long flights over the meadow. Here it has identified a vole’s position and is beginning its dive straight down.

Upon catching a vole, it seems that the first thing it does is t0 dispatch it. Here, the owl is bending down to the left and the captured vole is dangling from its beak.

Strangely, while grasping the vole in its talons, it often looks up. It is too big to be concerned about predators, but it may be watching for anything that could steal its prize.

The final three pictures show the owl with a vole in its mouth in a couple of stages of eating it. This view was taken by Cynthia.

Here is another view of the freshly dead vole, but the owl is still looking around for thieves.

Now, always head first, it eats the vole.

Great Grey Owl: This is the third of five planned sequential postings on this largest owl.

Having spotted a vole either by sight or hearing, the Great Grey Owl flies to catch it.

The Great Grey takes off from its perch.

And begins to extend its wings. Photo by Cynthia.

The Great Grey Owl is now flying noiselessly to catch a vole.

A back view of it flying after something in the field. Photo by Cynthia.

And a shot of the Great Grey Owl flying back to its perch. Photo by Cynthia.

Great Grey Owl: This is the second posting on a planned sequence of five postings on this largest owl.

The Great Grey Owl visits briefly beside the North Arm of the Lake during many a winter. It comes to hunt voles in a field.

It spends a fair bit of time perching somewhere, just looking around and listening for those voles. While perched for a large amount of time, one just sees the back of its head as it looks the other way. However, these pictures are biased towards seeing the eyes. It also looks and listens as it hunts on the wing. Presumably, after running low on voles in that field, it just moves on.

This owl owes a great deal of its success to its enormous facial disc, the largest disc of any owl. Its considerable size separates the ears and significantly helps it position things it hears in the horizontal. But, it doesn’t stop there. It has one ear higher than the other, which enables it to pinpoint sound in the vertical as well. This is added to super sensitive hearing which may even enable it to hear the heart beat of a vole beneath a foot of snow. But, while the owl can hear the vole, its own flight is virtually silent, so a vole does not hear it coming until it is too late.

A power line runs down one side of the field. Much time was spent searching from it.

The owl looks in all directions, but most of the pictures taken show its face, not its back.

As it moves about, pilings also served as a searching position. Photo by Cynthia.

Only once did it perch and search from a tree.

But while there, it fluffed its feathers. Photo by Cynthia

The Pygmy Owl is our smallest owl. In the warmer months, it lives high in the mountains, but sometimes it visits the valleys in the winter. This year, there are many Pygmy Owls here and I have treated them in four postings. The Pygmy is unusual in a few ways: in addition to being our smallest owl, it is active during the day and hunts by sight.

The Great Grey Owl is our largest owl. Although it is found mainly to our north, many years it will spend a few weeks hunting for food in the occasional meadows along the North Arm of the Lake. This year, it is here, so Cynthia and I visited to watch it.

In planning some postings on the Great Grey Owl, it struck me that pictures of these two winter owls could be deceptive: independent of size, we have the critter nearly filling the frame. So, relative size is not revealed. This initial posting corrects that. First I show the two owls with their standard frame-filling pictures. Then a composite shows the approximate relative sizes of the two of them. 

Subsequent postings will just present the Great Grey: as it hunts from a perch, as it flies, and, as it catches a meal. Interestingly, both the Pygmy Owl and the Great Grey Owl enjoy eating voles.

Our smallest owl is the Pygmy Owl.  

Our largest owl is the Great Grey Owl. In these pictures, size is not apparent.

This is a composite picture of our largest owl, the Great Grey Owl (left) and our smallest owl, the Pygmy Owl (right), both flying. They are strikingly different in size.

Some winters, I hardly see even one Pygmy Owl. This year, I cannot stop seeing them. We saw three different ones in a short time yesterday.

It gave me the opportunity to try photographing one in flight.

As daytime hunters, Pygmy Owls have sharp vision for locating prey. So they can obviously see humans wandering nearby. The Pygmy Owl certainly knew we were watching it, but as we were neither a suitable predator nor prey, it just seemed to ignore us.

Of course, while it will always fly off to snare prey, it would often time its departure for when we looked away or had gone. It is as if it wanted to hide its next location from observers. So, photographing one flying was a problem.

There were many pictures of owls sitting and hunting, but only one so-so shot of an owl  flying off. Ah well.

Here is one of the Pygmy Owls when it was hunting.

It flew off rapidly, but for less that a second, it was still sort of in focus (and still watching).

After showing a male Pileated Woodpecker foraging on a piling a couple of weeks ago <http://blog.kootenay-lake.ca/?p=33997>, Cynthia found another foraging pileated. This new one was a female. So, I am showing both.

First, I will reproduce the male from the two-weeks old posting. It has a reddish malar strip (from bill down to neck). Its red cap also extends to its bill. 

Second, here is Cynthia’s shot of the female from the latest observation. The malar strip is black (not reddish) and the red crest stops above the eye. The darker eye colour seems to be only a result of the age of the bird, not its sex.

This shot of the female shows the red crest stopping well above the bill, and the dark malar strip. But, the real reason it is included is that it is an unusual view.

Some winters, I have been able to photograph a Pygmy Owl. 

This small owl spends most of its year at high elevations, but sometimes seeks the valleys in the winter. Unusually, it hunts by day and will sit quietly for hours on a tree branch waiting to fly after a small bird or maybe a vole. Then it has a quick dive to catch its prey.

However, in many winters of watching, I have never seen it fly after something. All my shots are just of the owl sitting and watching. That is, until yesterday when I watched the Pygmy Owl go after a small bird. The bird escaped, but I managed an acceptable shot of it diving after it.

A Pygmy Owl dives after a small bird, claws at the ready.