Bat feast

 

It was an amazing experience to sit amidst a horde of hunting bats.

Derek Kite alerted me to the shoreline feast. For an short intense period in the late evening, the air above a tiny stretch of beach became filled with swift, silent bats feasting on hundreds of mating mayflies. Abruptly it all ended, only to be replayed the next evening.

Derek and I adopted different photographic strategies. He tried to record bats as they approached and left the feeding area; I tried to capture the action just offshore. Each approach had a remarkably low yield. We were, after all, attempting to photograph small, dark, swift flyers in unknown positions at night. His percentage of somewhat acceptable shots was about 1%; mine was even lower.

But, what fun.

In Derek’s first two pictures, the bats seem to follow a line of rocks as they leave the feeding grounds.

I managed one head-on shot over the water.

And while the bat (and its reflection) is soft, it does show one hunting amidst the crowd of mayflies.

Derek Kite’s pictures are used with permission.

Posted in mammals | 8 Comments

Alula landing

 

A bird’s deployment of alulae is a remarkably transient event. If you blink, you will probably miss it, for each event lasts less than half a second. Yet, it is fun to spot these bits of aerodynamic wizardry which perform the same function for a bird as do the slats on an aircraft.

Half way along the leading edge of bird’s wing there is a bend that is analogous to a person’s wrist. An alula corresponds to a bird’s thumb. It is usually held flush to the wing to minimize drag during normal flight, and so passes unnoticed. Yet, birds have the same problem as do aircraft. To land, they must slow, but doing so decreases lift and control. To minimize this loss of lift, the bird tips back to increase its angle of attack. This can lead to a stall as the air ceases to flow smoothy over the upper surface of the wing. A bird’s deployment of alulae forces the airflow back over the wing’s upper surface, allowing the maintenance of adequate lift and control.

I was watching a heron hunting in a marsh. And although I felt that my twenty-five metre distance would not be threatening, the heron thought otherwise and flew farther away.

It flew low over the grass to a spot about double the distant. The Great Blue Heron cruises at about 40 km/hr and now must come to a graceful stop. If it were landing in a tree, it could approach from below and use gravity to slow. However, on a level surface, its wings need to do all the work.

It begins to tip back. The increased angle of attack increases drag slowing the bird and also partly compensates for the decreased lift at the lower velocity. Alas, it also increases the likelihood of a stall with its loss of control. At this time the alulae are deployed. They are the raised feathers halfway along the leading edge of the wing (at the wrists).

With its alulae still deployed, the heron tips back even further. The ruffled upper coverts (feathers that cover the wing) probably play the same role as vortex generators on aircraft wings.

Alulae are no longer needed as the heron swings its feet forward to alight.

And all of this was seen because the heron apparently wanted to double its distance from me. Successive landing pictures were separated by about a fifth of a second and the alulae were deployed in two pictures—about the time span of the blink of an eye.

Posted in birds | 1 Comment

Shore patrol

 

The darner season is upon us. 

Darners are a group of large, colourful, dragonflies that relentlessly patrol shorelines for insect prey. Happily, they are voracious eaters of mosquitoes. Unlike some groups of dragonflies that hunt from a perch—and so are fairly easy to photograph—darners are almost always seen on the wing. Photographically, they constitute a small rapidly moving target many metres off upon which framing and focussing is difficult. Many shots are taken; few are successful.

This Paddle-tailed Darner is patrolling the shoreline. To ease flying, its legs are tucked out of the way. 

When the darner turned roughly in my direction, its sunlit wings flashed like a burst of fireworks.

Posted in bugs | Leave a comment

Wood Duck chicks

 

I don’t suppose that any local birder would doubt that Wood Ducks breed around the Lake. Yet, they are remarkably secretive about doing so. Frequently seen are the chicks of Mallards, Common Mergansers and Canada Geese, but not Wood Ducks.

At least, this is the first time I chanced on Wood Duck chicks. Curiously, despite the large number of campers at Kokanee Creek Park, this skittish species was secreted not far from a busy campground.

There were at least four chicks, but only the mother and two of them appear in this grab shot taken though foliage just before they all vanished, presumably as a rebuff to my presence—although, I really wasn’t all that close. 

Posted in birds | 1 Comment

Sapsucker

 
Male Red-naped Sapsucker, 2010

 

For a week I have been visited by sapsuckers. 

Early one morning a week ago, I first heard and then spotted two sapsuckers on a utility pole, but managed a picture of only one of them before they both flew off. That bird, posted to recent birds and reproduced below, is a male now identified as a Red-naped Sapsucker.  

Since that time, I have heard a sapsucker a half-dozen times but only managed a few more pictures, always of a female Red-naped (one of which is below).

The odd thing about this is that sapsuckers drill holes in trees and then sip the sap that flows. Certainly, that is how I have seen them before, as in the shot of a male working his way around a mountain ash (on the right). This time the sapsuckers seemed to confine themselves to the utility pole, something that clearly lacks sap. They were probably drumming on it to communicate, rather than feed.

This is the first sapsucker (male) seen a week ago.
Its partner went unrecorded at the time.

This is one of a few pictures of the female captured over the subsequent week as it hammered on the pole. Although it was primarily in the shade, there was a moment when shifting leaves allowed sunlight on its red crown.

Posted in birds | 1 Comment

Anise Swallowtail

 

In Acorn and Sheldon’s book, Butterflies of British Columbia (Lone Pine Publishing, 2006), the Anise Swallowtail is described as

the most common swallowtail west of the Rockies.

Locally, I have had frequent views of both Western and Pale Swallowtails: e.g., butterfly love, yard delights, butterfly symposium. Yet, it was not until a couple of days ago that I saw my first Anise. Further, another long-time butterfly watcher at the north end of the Lake, saw her first Anise only a month ago. 

How is it possible that what the experts claim is common goes substantially unseen by keen local observers? I don’t know, but a clue might lie in the fact that we live in a well treed region and, as Wikipedia notes:

The Anise Swallowtail is a butterfly of fairly open country….

Could it be that those authors were more familiar with the open countryside of the central southern regions of the Province than they were of the forested West Kootenay?

This Anise Swallowtail rarely opened its wings after it alighted, so it was difficult to get a classic shot of spread upper wings. However, this picture provides a definitive view of the top of two of the four wings.

Male butterflies often sip moisture in wet sand. The accompanying nutrients apparently increase fertility.

An Anise Swallowtail Butterfly sets out to increase his fertility.

Posted in bugs | 1 Comment

Cinnamon black bear

 

Black bears were given their name by early European settlers along the eastern shore of North America. There, and along the south coast of British Columbia, black bears are obligingly black.

Around here, however, black bears come in a delightful range of colours: black (some with, most without the white V), chocolate, cinnamon, beige, and even cream (white?). Indeed, in May, this blog posted pictures of sibling cubs, each of a different colour: polymorphistic bears

I was tempted to suggest,
Cinnamon is the new Black,
but thought it a tad tacky.

Ron Welwood has sent me a picture of a cinnamon-coloured black bear that roamed through his yard last week. I wish I had been there to see it.


Ron Welwood’s picture is used with permission.

Posted in mammals | 3 Comments

Loafing time

 

Painted Turtles love to spend a warm summer’s day loafing on a log. And why not?

Posted in herptiles | 2 Comments

Two-snake day

 

There are two species of Garter Snake around the Lake: Common and Western. And while today I saw two snakes, each was the slightly less common Western Garter Snake.

A nice thing about the observations was that each appeared in a different one of the snake’s favoured habitats: water, meadow. The snake has a varied diet and finds things to eat in both places.

Most Western Garter Snakes in the Province have prominent stripes, but our interior variety has a more mottled pattern, as is seen in these shots.

This snake had a regular foraging pattern, going back and forth over roughly the same stretch of water. While that made taking pictures a bit easier, the snake did not keep to a regular schedule. 

In somewhat dimmer light, this one foraged in a meadow. It left when it saw me, so I didn’t discover its routine.

Posted in herptiles | 1 Comment

High-altitude finch

 

The Grey-crowned Rosy Finch is not a bird that is often seen, at least not by valley dwellers. It breeds high in the mountains, usually in the vicinity of permanent snowfields.

So it was that on hike up to the Kokanee Glacier last Saturday, Doug Thorburn photographed one and noted:

I didn’t get to spot a nest, but I could hear them
feeding young somewhere nearby.

 


Doug Thorburn’s pictures are used with permission.

Posted in birds | Comments Off