Two female Ruffed Grouse in my yard were standing nearby while watching another: a male in display. He had erected his eponymous ruff, the long black feathers on his neck, and had spread his tail feathers to form a fan.
The message was clear: “I want you, baby.”
This Bald Eagle exhibits anisocoria.
A half-dozen years ago, I posted an eagle portrait. It was taken just as the light from the rising sun touched one side of the eagle’s face. A striking feature of the portrait is the eyes: The pupil on the sunlit side is smaller than that on the shady side.
In most humans, the pupils are synchronized, and so the size of the pupils match. When they do not, the usually harmless condition is known as anisocoria (aniso = unequal; cor = pupil; ia = condition).
Of course, birds are not people; their eyes behave differently. It seems that anisocoria is a normal characteristic of birds. Yet, I hadn’t noticed it again until today when a Great Blue Heron looked down on me. Again, the lighting was uneven, and, like the eagle, the heron exhibited anisocoria.
The lighting on the two sides of this heron’s face is different, resulting in different pupil sizes.
There are worse ways to spend the better part of a day than wandering through nature. Here are highlights of things seen two days ago.
Turkey Vulture
Vultures return to this area mid-March, but I would not have expected to see one so quickly, let alone have the unusual view of the topside of its wings.
Northern Shrike
This is the first time I have seen a shrike with prey, and a vole, no less. Unfortunately, the shrike was flying just behind a red osier dogwood.
Elk
This is a portion of a much larger herd of elk seen in the distance.
Killdeer
A killdeer flew by.
Northern Pintail
The pintail is an elegant-looking duck, but I have rarely seen more than two at once. This flying flock was spectacular.
Rookery
The season is early, but this view of a portion of a rookery already shows a half-dozen Great Blue Herons and a couple of Double-crested Cormorants.
Red-tailed Hawk
When leaving its perch, this hawk spread its wings and tail.
Red-winged Blackbird
This male was in full song and full display.
Ruffed Grouse have been hanging out in my yard. Two are below. Might we hope for chicks?
In the dying months of winter, I watch talus for the emergence of Yellow-bellied Marmots from their long hibernation. For many years, that first observation was in March, but then it began to shift until it was well into February. The result of global warming? Maybe, but a more likely culprit might be found in the year-to-year vagaries of snow that covers the talus, rather than a systematic shift. There is just no point in heading out with all that cold, white stuff covering everything.
A couple of Yellow-bellied Marmots emerge in a portion of the talus only recently bereft of snow.
This seems to be a season for visitors that have wandered off course from the Coast. Last October there was a Pacific Loon, and a couple of days ago, a Eurasian Wigeon couple. I did not see the wigeon at the Nelson waterfront, but two people told me about it, and Shirley Smith sent along a fine shot of the couple.
There are two species of wigeons seen in the Province. The American Wigeon is a staple of this region throughout the year. The first picture is of it.
Our standard wigeon is the American Wigeon. The male, at the back, has a whitish or buffy forehead, and a greenish band from his nape to his eye.
It is much less common to see the Eurasian Wigeon. Again the male is at the back, and again he has a buffy forehead. However the rest of his head is distinctly rufous. There are differences between the females of the two species, but they are subtle. The couple moved on the next day.
Shirley Smith’s picture of the Eurasian Wigeon is used with permission.
Mountain Bluebirds turn up in March. But, just try to get a picture this early in the season.
A Mountain Bluebird hunts from a fence post for insects, something still difficult to find.
From its perch, it headed out and caught something.
While watching bluebirds, another hunter was spotted: a raven flying by carrying a vole.
Throughout the winter, whenever I saw one dipper encounter another, the competitor was driven off. That all changed this fine sunny spring morning.
In courtship, the male will strut and sing in front of the female. If he makes a good case, the female joins in the strutting and singing. In this case, she did not. Ah well, the season is young.
A dipper pledges his troth. She doesn’t buy it.
Crests, on birds that have them, are feathers extending from a
bird’s head. Different configurations might be named crest, hood,
horns, or ears. This is a female Hooded Merganser (2014/04/27).
Only a few birds sport crests. A bird with a crest can raise or lower it, but will raise (erect) it to communicate aggression or sexual arousal.
While a crest is sometimes lowered (collapsed) on a perched or floating bird, the crest always seems to be collapsed on a flying bird.
The reason a bird would collapse a crest when flying is fairly obvious: an erect crest during flight would produced extra aerodynamic drag. This would make flying more arduous and induce the bird’s head to tip upward, problems easily avoided by collapsing the crest.
It took me a long time before I noticed the pattern whereby a crested bird systematically collapses its crest during flight. Why was this pattern so difficult to spot?
• First, much of the difficulty seems to come from the problem of spotting a behavioural negative: a crest not erected. Indeed, the literature on a bird’s crest seems to concentrate on occasions when crested birds show them — not when they systematically do not.
• Second, even collecting evidence of a crested bird’s appearance during flight is difficult merely because the photography is difficult. Evidence for this is easily obtained with a web search of the image of a small bird. The fraction showing flight is small. (I even wrote an essay about the reason for the problem.)
Given these difficulties, my small sample, below, can only be suggestive of a consistent behaviour of flying with crest lowered.
Granted, the crest is not always displayed even when the bird is moving slowly, but I will show pictures when it is. Then I show pictures of the bird flying, a time when I have never seen a crest deployed.
I start with the bird where I first recognized the behaviour, but not the broader pattern: the Great Horned Owl. The horns are merely the owl’s crests, which seem always to be deployed except during flight. A perched owl displays its horns, but then flying, the owl collapses its horns.
Unliked the Great Horned Owl, the Double-crested Cormorant only shows crests briefly during breeding season. Two white crests are seen in the first picture, but even though the second picture shows aggression, because the cormorant is flying, the crests are collapsed. Taken together, the owl and the cormorant prompted me to look through my pictures for other examples. I found none where a crested bird hadn’t collapsed it during flight.
The Belted Kingfisher frequently has its crest erected when perched, but not always. I have seen it fly many times but always with its crest flattened (next picture).
Both male and female Hooded Mergansers erect crests in response to sexual arousal. However, even when flying together, the crests are flattened.
The Steller’s Jay is rarely seen without its large crest erected. That is, until it flies.
Both the Bohemian and Cedar Waxwings raise their crests only occasionally. But, when flying, each has it lowered. I illustrate this with a perched Cedar Waxwing and a flying Bohemian, although I could have done it the other way around.
My final illustration is particularly interesting as it requires three pictures to discuss. First is a female Common Merganser with her chicks. She has a raised crest. The second shows both a female and male flying with crests lowered. Finally, birds planing is another time where speed is needed and so the crest is lowered to reduce drag. (See my essay on planing water birds.)
There appears to be a consistent pattern here: When crested birds need speed, they lower their crests to minimize aerodynamic drag.
Dabbling pits
The low water of March is the time to see freshly exposed mud spotted with dabbling pits. Why mud? Why dabbling pits?
Turn back the calendar to the normal water level of the previous summer. Waves wash the sandy beaches of the West Arm. The breaking waves pick up sand of all sizes and first wash it a short distance up the beach. The water then flows back down the slope but now carries the sand grains and silt out into the Lake.
However, not all particles are treated equally: as the velocity decreases as water flows back into the Lake, the larger grains of sand settle out adjacent to the shore, while the silt is carried a bit farther offshore. The process is repeated with every wave.
The particles that had been picked up by the waves have been sorted, with the bigger ones near the water’s edge and the smaller ones farther out. The offshore silt results in the mud that is a staple of beaches along the West Arm.
The mud becomes a home for a rich range of tasty biota. Dabbling ducks, geese, and swans love to feed there. They tip their butts in the air and extend their necks downward as their bills make circular sweeps in the mud in search of delectables. They dabble in the mud.
It is the dabbling pits that water fowl make in mud that are exposed when the Lake level drops.
The Canada Goose is one of many dabbling water birds to tip up and sweep the mud below.
Low water exposes the dabbling pits made earlier by water fowl in what had been offshore mud.
