Plane harassment

 

No, the title does not contain a spelling mistake. I really do mean plane, not plain

This was an observation that would warm the cockles of the heart of any bird behaviourist: two male Common Mergansers were competing in their harassment of a female — and doing so while all were planing. 

About the harassment: This is the breeding season and the males chased the female back and forth across the water before mating. The mating took place behind a dock, but subsequent behaviour made it clear what had happened. I will let the pictures speak for themselves on the issue of harassment, and concentrate on the feat of planing.

When moving across a water surface, most birds, mammals, and boats are in displacement mode: they are supported primarily by buoyancy. Their speed is effectively limited by (what is known as) their hull speed. Some birds have the power to temporarily plane, just as can some recreational boats. (Among adult birds, those with the power to plane seem to be mainly divers.)

When planing, a bird or boat is supported primarily by the rush of the water against its tipped-up body. For a boat to plane, there also needs to be a sharp transition between the bottom of the hull and the transom to force a separation of the water flowing underneath. A bird has a rounded butt, which normally would prevent planing. However, when a bird wants to plane, it changes its shape by forcing its tail down into the water to create the necessary sharp transition. 

Male mergansers harass a female while all plane. Bodies are tipped up and tails are pressed down.

Planing is hard work. Sometimes when a bird tires, wings are used for supplemental power.

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Budding buck

 

A deer’s antlers are regrown each year. They start in the spring as buds and grow quickly to full size in about four months. This morning’s white-tailed buck shows only a few day’s growth. Indeed, the growth is about the same as that of a moose posted eleven months ago.

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Friends in residence

 

I generally try to sample delights throughout the neighbourhood of Kootenay Lake — a rather substantial area. However, the neighbourhood sampled for today’s posting is rather constrained: things seen in or from my yard over the last few days. Of course, there have been the usual collection of yard birds: Steller’s Jay, Black-capped Chickadee, Song Sparrow, Northern Flicker, Tree Swallow, Bufflehead, Common Merganser, and Robin. Here are a few others. 

That so much wildlife is willing to share its space with me is reason enough to live here. 

I usually think of Mallards as being fairly gentle creatures, so this couple’s recent behaviour was unexpected. A few weeks ago, two Mallard couples would visit. Then the male of one couple was killed (by what, I don’t know) and a Merlin had it for breakfast. That left its female partner to fend for herself. This couple have mercilessly abused her. Each has attacked her and driven her off from good feeding spots, even to the extent of ripping out some of her feathers. Apparently, they want to preserve the resources for the development of their own chicks, not hers.

A White-tailed Doe and her two yearling fawns are frequent visitors.

The Snowshoe Hare seen earlier about my yard is continuing its moult into its summer coat.

It will be interesting to watch a Canada Goose sitting on her nest in the open. I look forward to the emergence of the chicks.

The Merlin that ate the Mallard has appeared repeatedly atop a tree and spent its time making a call that I had not heard before. Another Merlin responded to it and they mated (twice). It seems that this Merlin was a female seeking some company.

Now and then, I see a Ruffed Grouse in my yard. This one looked as if it might be nesting. Alas, it has not been seen there since.

Clearly, not in my yard, but seen from it at dawn, a Common Loon languidly drifts along the Lake.

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Eagle hovering

 

Little birds can hover, but not soar; big birds can soar, but not hover. 

By hovering, I mean (what is called) true hovering: staying aloft by flapping rather than by moving horizontally through the air and doing so for an extended period of time. The kingfisher is probably the largest bird capable of pulling this off. 

Occasionally, one does see an osprey or an eagle seemingly hover over a spot below. This is always done when flying into a brisk wind, so the bird actually is moving through the air, but has matched its speed to that of the head wind. Even then, the activity is so energy intensive that the bird can only maintain it for a few moments. 

A large bird wants to do this is so it can position itself for an attack on prey.

A Bald Eagle seems to hover in a brisk wind as it eyes a potential prey (probably a duck) below. It did so only briefly before plummeting to the lake surface, but it missed the target.

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Osprey arrives

 

Ospreys are back.

I saw my first Osprey of the year fly by last Monday (April 10th), but failed to get a picture. Others have seen them along the lakeshore throughout the week. Yesterday was the first time I managed a picture. Thus begins the nearly half-year local season of ospreys.

A (male) Osprey flies along the shore.

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Merlin’s breakfast

 

Lying in the sand is a male Mallard — at least it used to be.

Standing over it, the Merlin looks at me and says:

“If you try to take my breakfast, I will eat you, too.”

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Hare’s hair

 

Seasonal bunny: This hare showed insensitivity to mythology by neither laying nor hiding eggs.

A hare’s hair moults.

Our local snowshoe hare (we don’t have rabbits around here) is white in winter and rusty brown in summer.

The transition between white and brown is determined by day length, rather than snow cover, so sometimes there is a mismatch with surroundings that makes a hare vulnerable to predation. Indeed, it can live or die when its coat does, or does not, provide adequate camouflage.

This was the first time I had seen a hare midway in its moult from white to rusty brown.

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Mountain Bluebirds

 

Why watch for Mountain Bluebirds each spring?

They are stunning beautiful.

Typically, Mountain Bluebirds arrive to breed in late March or early April. This year, a few turned up on schedule, but the insects they feast upon were tardy. Jaunts to see bluebirds found numbers to be sparse — until this last weekend. 

How could this creature be named anything other than bluebird?

The muted colour of the female gives better camouflage from predators.

A male had flown down to the dried grass in an unsuccessful raid on an insect.

“You needn’t even try to photograph me in flight; I am way too fast for you.”

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Otter in suspension

 

A travelling animal can employ various gaits, a word that describes the pattern of movement of limbs during locomotion. A bipedal human might walk, hop, or run, each a different form of propulsion. The transition from one gait to another takes place when the energy it takes for, say, a fast walk begins to exceed that of a slow run. Quadrupeds, such as a horse, deer, or dog often have a wider range of choices which might include: walk, amble, pace, trot, canter, gallop, run, or stot. 

A trotting mule deer is in suspension (2011).

A characteristic of some of the faster gaits is a period of suspension: a time when all four feet are off the ground. It seems that the faster the animal moves, the longer the period of suspension: Aerial time matters for speed.

Many rapidly moving quadrupeds exhibit a period of suspension.

Do otters?

A 2002 paper that studied the running energetics of the River Otter noted that:

… the ability to incorporate a period of suspension during high speed running was an important compensatory mechanism for short limbs…. Such an aerial period was not observed in river otters….

An otter family walking; None are in suspension (2015).

It is interesting that the authors of this study did not see a running otter in suspension. I do not know how the paper’s authors motivated the otters to run, yet that motivation clearly wasn’t sufficient to prompt them to excel.

I recently watched two otters in suspension while they were running and the motivation seemed to be purely that of having fun — otters, after all, will be otters.

This running otter is in suspension. It was racing along a dock before making a great leap into the water — rather like a child racing up a diving board before leaping off the end. The first otter was followed by a second that did likewise. It seems that pleasing a researcher isn’t as important to a River Otter as having fun.

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Tomfoolery

 

I commented that we should keep an eye out for male Wild Turkeys in display. It is that time of year. And there they were: not one, but two.

After watching the two toms for a while, it struck me that there was something odd about their behaviour. Each was decked out in its striking courting plumage and there were a number of females in the neighbourhood. Yet, rather than seriously approach the ladies, the two toms stuck so closely together that they were almost always touching.

Were they more interested in each other than the ladies? Well, sort of. Neither seemed interested in the other sexually, but saw him as competition. It seems to have been a example of

keep your friends close, but your enemies closer

which was memorably stated by Micheal Coreleone in the movie, Godfather, Part II (1974), but which originated in Niccolò Machiavelli’s, The Prince (1513).

The two turkey toms appeared inseparable.

Females were plentiful, but so obsessed were the males with blocking the other’s access, that neither made conquests. It was all rather funny and pathetic.

So the toms wandered away loveless, each presumably pleased the other had been thwarted.

 

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