Exploring Kootenay Lake

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. 

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.”

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.