Mid-October

 

October is a month of transitions.

Katabatic winds flow out over the water and give rise to ephemeral sprites of steam fog. Curiously, despite the gentleness of the wind, a steam devil emerges.

The orangish colours of Western Larch have spread around the shore.

Big-horned Sheep have gathered in anticipation of the forthcoming rut.

 

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Grebe & fish

The Pied-billed Grebe gains its name from the dark band around its bill, seen only during the breeding season (2012/04/21).

 

Our four regular grebes all dive underwater to forage. The smallest of these is the Pied-billed Grebe. It mostly eats small fish and crustaceans, such as crayfish, which it captures and crushes with its stout bill and strong jaws before swallowing them.

After it surfaces with a prize, one has to be fast to see what has been caught, for the prey is swallowed in a trice.

A nearly five-year old picture, shows a Pied-billed Grebe downing a crayfish (2015/01/08).

Yesterday’s Pied-billed Grebe took only five seconds to down a small fish after surfacing.

 

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Scoter goes astray

 

Surf Scoters are really uncommon visitors to this region.

In the summer, Surf Scoters breed beside small boreal lakes, all of which are at least 800 km north of here. They winter along the Pacific coast, over 400 km to the west. Scoters have scant reason to pass this way during migration and so are rarely seen. However, now and then, storms drive them astray.

A male Surf Scoter visits.

 

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Soon to go

 

Warm-season insectivores leave the region in October as the supply of insects and spiders diminishes. Many head for the southern USA, Mexico, or Central America. Three of these soon-to-be departed species were seen on a walk in yesterday’s sunshine.

A Savannah Sparrow flies to another perch, but soon will fly far to the south.

Another Savannah Sparrow hunts a diminishing supply of insects from a branch.

A Chipping Sparrow hunts near the ground.

My favourite shot is of a female Common Yellowthroat. She, too, will fly south soon.

 

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September goulash

 

This September’s goulash is thin gruel: only two previously unposted images from a generally sparse month of postings.

There are two unusual features to this picture of a chipmunk. I usually see chipmunks in the mountains rather than at the bottom of valleys. Further, this little fellow has been spending a week raiding a bird feeder and is seen here working on one of its seeds. I am used to squirrels raiding bird feeders, but not chipmunks. This is all rather odd.

This is an immature Bald Eagle with wings spread to apparently dry them after fishing for Kokanee in the stream below. Whenever I see an eagle drying its wings in this way, they are not spread wide, but shaped in a delta. Possibly this is to make it easier for water to drip off them.

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Magpie iridescence

 

Magpies do not favour this region because it is highly forested. These birds prefer open habitats with occasional clumps of trees. Consequently, there are few opportunities to capture pictures of magpie iridescence.

The pigmentation of a magpie’s feathers produces a plumage that is strictly black or white. Yet in some lightings, the black feathers on the wings and tail produce brilliant colours, particularly blues and greens. These colours do not result from pigmentation, but iridescence.

Cells in the iridescent feathers contain a basal melanin layer, which produces the black by absorption. Above are stacked reflecting platelets, which produce the iridescent colours when light reflected from one layer interferes with that from another. The resulting colours are bright, pure and strongly directional. A bird can use this for flashing a signal in one direction, while remaining inconspicuous to a predator in another direction. 

Of the handful of pictures of the Black-billed Magpie I have taken, only a few of them show the blue-green iridescence of the wings. In this picture, taken two days ago, the tail just looks black.

However, contrast that black tail with the brightly iridescent tail of the same bird seen a half-minute later. Who knows what signal it is attempting to send?

 

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Pileated in training

 

It is not a regular sight to see two Pileated Woodpeckers jointly foraging on the same tree. On the two previous occasions the foragers were a male and female. As the Pileated Woodpecker is both monogamous and territorial, a foraging couple makes sense.

So yesterday, when I came upon two woodpeckers foraging on a utility pole, I just assumed that these two were also a male and female. Yet, the pictures revealed them to both be male.

The territoriality of Pileated Woodpeckers suggests that these two males are either rivals or family. The two of them seemed to work together and passed signals back and forth, so they probably are not rivals. But, is it a case of a father training a son? 

Cornell Lab of Ornithology notes: “Once fledgling Pileated Woodpeckers can fly well, they follow adults everywhere, depending on their parents for several months to provide and help find food. Come fall, young will separate from their parents and wander until spring, when they will attempt to acquire a mate and nest.” So, this pair is likely to be a parent and child and the pictures, below, are interpreted in the light of this assumed relationship.

Adults have yellowish eyes, while the chicks have brownish eyes. While the difference is not striking with these two, the father seems to be on the left and the chick on the right.

Signals are sent back and forth. Here, daddy tips his head back and emits a strange sort of cooing call, to which junior responds with spread wings.

It is unclear what message is being communicated here. 

However, the training seems to be successful as the chick does find some grubs. 

 

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Cooper’s Hawk

 

It is certainly fun to spot a Cooper’s Hawk along the lakeshore, for I only get to see it about once a year. This is a raptor that mainly preys upon smaller birds. 

Yet, there is something rather odd about my sightings:  I have only ever seen immature Cooper’s Hawks. Where are the adults?

A immature Cooper’s Hawk sits atop a utility pole. 

“Quit watching me while I practice my dance routines.”

 

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Osprey migration preparation

 

Around mid-September adult ospreys migrate. They have nested, raised chicks, and sent them off on their own. Now is the time to head south for the winter. However, that requires building up fat reserves by feasting on fish. (Juvenile ospreys migrate separately a few weeks later.)

Earlier in the week, an adult osprey fed in the early morning light. It spent most of its time feeding on the piling with its wings folded. But, occasionally it raised its wings to adjust the position of its fish, and that made for a couple of dramatic shots.

 

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Spread wings

 

The explanation for why a bird spreads its wings when flying is obvious: the spread wings aerodynamically support its weight.

However, when a bird is standing or floating on water, its wings are normally, but not always, folded. There seems to be a variety of reasons for a bird that isn’t flying to spread its wings: drying them, warming them, baking parasites, signalling, regaining lost balance, and preparing to fly. 

Although this compilation makes it look as if these postures are frequent, they are not. Two of the images below are new, but previously posted images have been pressed into service to illustrate reasons that wings might be spread while a bird is standing or floating.

During flight, this heron’s spread wings aerodynamically support its weight. However, when a bird is perched, its weight is supported by its legs. What would prompt a perched bird to spread its wings? 

Drying feathers
A compelling explanation for a bird having spread wings when perching is that it is drying its wings. This actually seems to be the case with this Bald Eagle, which had just been fishing for Kokanee in a stream. I have only seen an eagle adopt this pose twice, and on each occasion, the wings were only partially spread.

However, following a bath in the lake, this Bald Eagle stands in the shallows, spreads its wings, and shakes off the water.

Warming
Another circumstance occurs after a cool night when the bird warms its wings and body in the morning sunlight. This seems to be the explanation for Turkey Vultures exposing their spread wings to the rising sun.

Baking parasites
A curious case of spread wings is illustrated by this Great Blue Heron: it is exposing its spread wings to sunlight so as to bake the parasites in its wing feathers. Its extended neck, and panting, then cools the blood reaching its head so as to prevent the hotter blood from reaching its brain. 

The balalaika-like pose of the heron is mimicked by a Turkey Vulture, so one suspects that it, too, is baking its parasites.

Signalling
The above poses can be fairly long lasting. Of somewhat shorter duration are those shown in the next images. The spread-wing posture can be used to signal. This dipper is telling an adjacent dipper to stay clear of its foraging area.

Similarly, this loon is signalling a perceived interloper to move out of its territory. 

These Canada Geese seem to use synchronized spread wings in their courting.

This is one of the ways a male Hooded Merganser signals his interest to a nearby female.

Maintaining balance
When mating, a male osprey spreads his wings both to support its weight and maintain balance.

This is also the case for the mating Tree Swallows. 

Sometimes a perched bird loses its balance when eating and spreads its wings to regain it. Here a Pileated Woodpecker is foraging on elderberries.

And an osprey briefly uses its wings to maintain its balance as it adjusts the position of its fish.

Preparing to fly
This juvenile osprey has yet to fly, but it practices by facing into the wind and spreading its wings.

Finally there is the momentary spreading when an adult bird is still perched, but about to fly. 

 

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