Math: how far away is the goose?

Tutoring math, you notice that people like relatable examples. The tutor brings up his observation of a Canada goose.

Looking out over a lake in Nanaimo on Sunday morning, I saw an exceptional Canada goose swimming apart from the others.

The setting was so tranquil, even distance seemed irrelevant: I felt that, on a whim, I could suddenly scoot down to the water, plunge in, and join the goose if I wanted. Yet, how far away was it, really?

Holding my phone at 20cm, or 200mm, I observed the goose at about one-sixth of my phone’s lens port, which is 7mm across. So, to me, the goose appeared 7/6=1.17mm. Yet, a goose that prosperous would likely be about 60cm, or 600mm, from tail to breast. From optics,

object distance/image distance = object length/image length

Therefore,

d/200 = 600/1.17

Multiplying both sides by 200, we get

d=200(600)/1.17 = 102574mm or about 103m

Source:

Bull, John and John Farrand, Jr. The Audubon Society Field Guide to North American Birds, eastern region. New York: Alfred A. Knopf, 1977.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Bird watching: horned lark?

Bird identification involves constant self-tutoring. The tutor describes a bird he saw, and attempts to identify it.

Yesterday’s sunny afternoon, I noticed something odd from the corner of my eye. I had no idea what it would be, just that it was different. I looked outside.

On the fence was a bird whose posture surprised me. I didn’t have my glasses, so quickly got them; the bird was still there. I didn’t recognize it.

The bird’s size was similar to a robin’s, but it didn’t stand like a robin. Its back was solid reddish brown, which petered into spots around whitish breast. I think it had a black collar. It had a white throat, some yellow (I think) near the eye, and a black circle below and behind its eye. Where the head wasn’t black, it was white or yellow.

A couple of times it flew to the lawn, then returned to the fence.

The birds I can find that look most like the one I saw: a juvenile robin or a horned lark. Conveniently, an adult male robin landed about six feet away on the same fence; it was the same size as the bird I’m describing. I don’t believe a juvenile robin, at this time of year, would be equal in size to an adult.

I heard the bird’s voice; it was producing single notes, around 10-15 seconds apart. That could be a horned lark or a robin.

I’ve read that horned larks aren’t necessarily known to breed here, but I’d say that’s what the bird was.

Source:

www.allaboutbirds.org

www.crd.bc.ca

www.allaboutbirds.org

Robbins, Bruun, et al. Birds of North America: a guide to field identification. New York: Golden Press, 1966.

Bird watching: Oregon dark-eyed junco

The tutor shares a welcome backyard observation.

Here on Vancouver Island, we’ve had a cold winter. Normally, we get spring weather starting by mid-February – not this year. It’s slowed down my activity as a naturalist.

Today, however, I noticed a couple of Oregon dark-eyed juncos in the backyard. At first, I saw two robins on the lawn, but quickly noticed two smaller birds (the juncos) near them.

Decisive features were the black head, light-colored beak and breast, and the flash of white tail feathers as they flew. The male had pink or orange shading on his shoulders. They hung around for about ten minutes.

I’m sure I’ve seen lots of these juncos, but never identified one. They live on Vancouver Island year-round.

Source:

Robbins, Chandler S. et al. Birds of North America: a guide to field identification. New York: Golden Press, 1966.

www.allaboutbirds.org

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Bird watching: when a hummingbird lands on a fence

The tutor shares an observation from yesterday.

Yesterday’s high was 24, but the humidex reached 28. Around here, that’s hot.

Working on the roof of a shed, I noticed, from the corner of my eye, about twenty feet away, something flying slowly back and forth. I was busy clearing the gutters, so didn’t look at first. The motion was persistent, so eventually I did.

The flyer was a hummingbird – quite a large one, I’d say: it was about a third the size of a sparrow. The hummingbirds I remember seeing in the past were typically not much bigger than a big bee.

This hummingbird would fly near a feeder, then return to a 2″x4″ board (part of a fence), where it would land. I’ve never seen a hummingbird land on a man-made structure, nor on a flat place. The ones I’ve observed in the past would always perch in a tree between flights.

I wondered if, the fence being in the shade, the hummingbird was seeking refuge from the sun on such a hot day.

I’ll be sharing more summertime observations:)

Source:

environment Canada

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Lifestyle: bird identification from field guide: white-crowned sparrow

The tutor shares another backyard identification.

If a person isn’t looking closely, a white-crowned sparrow is easy to miss, even in the yard. They forage on the ground, but can seem from a distance to be dull-colored and “just another bird”.

In fact, the white-crowned sparrow has a distinct song, but I don’t notice that it sings when it’s on the ground. You hear this arresting call, but can’t necessarily tell whence it came.

With the binoculars I identified a white-crowned sparrow last week. Only through them could I see the four distinct black stripes along its face and head, separated by glossy white. The white crown is unmistakable. The body is olive or brown, with black spots on the wings.

White-crowned sparrows are very common on the west coast; I’ve just never noticed one before. I’ll be sharing more of my backyard discoveries in future posts:)

Source:

Robbins, Chandler S., et al. Birds of North America: A Field Guide to Identification.
  New York: Golden Press, 1966.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Lifestyle: bird identification from field guide: rufous-sided towhee

The tutor shares another backyard bird identification.

Similarly with Audubon’s warbler (see my post about it here), I could only identify the rufous-sided towhee through the binoculars. I heard the call, detected flitting in a hedgerow, then raised the binoculars to it.

I’ve never noticed a rufous-sided towhee before; from the reading, they’re quite common. The bird was handsome, with a glossy white breast, red side, and the rest black. His wings were spotted with white.

The rufous-sided towhee has a distinct call; I haven’t heard him since yesterday afternoon. I’m sure he’ll be back:)

Source:

Robbins, Chandler S. et al. Birds of North America: A Guide to Field Identification.
   New York: Golden Press, 1966.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Lifestyle: bird identification from field guide: Audubon’s warbler

The tutor shares an exciting backyard observation.

While supposedly we’re in springtime, any given day can be like summer. Yesterday and today are examples. The temp is only 16C, but the air is soft and stable like a summer’s day.

Those chances I get to sit on the deck, I have my binoculars ready to discover birds. Yesterday I was rewarded after catching movement in a bush. I raised the binoculars to the spot, and saw a dazzling blue-grey bird with yellow cap, throat, and shoulder. The guide confirms he’s an Audubon’s warbler, which supposedly are very common.

I’m surprised I’ve never noticed such a flashy bird before. However, with the naked eye, I’d never have seen him. Such birds seem talented at hiding behind branches.

I’ll be sharing more bird sightings:)

Source:

Robbins, Chandler S. et al. Birds of North America: A Guide to Field Identification.
   New York: Golden Press, 1966.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Lifestyle: bird watching: Eurasian collared-dove

The tutor shares a discovery he’s awaited.

As long as a year and a half ago, I began hearing a new bird call. I at first thought it was hooting from an owl. I explored many owl calls here, but couldn’t match what I was hearing.

Eventually I heard that the call was not hooting, but in fact cooing, from a kind of dove that had recently taken up local residence. I listened to a couple of pigeons and/or doves on the internet; they didn’t match the outdoor call, but they were close enough that I came to believe I was hearing a dove. Without a true match, however, the case “went cold.”

As I mentioned in my March 28 post, I’ve been paying more attention to birds as a way to embrace spring. To that end, I got the binoculars out and scanned the neighborhood a few times, ready for a bird sighting. Yesterday, I heard the cooing again, and even saw a dove high in a tree across the road. Quickly fetching the binoculars, I got my first close-up of the bird. It flew away, but then settled much closer on some telephone wires, with its mate.

The bird seems to be a Eurasian collared-dove. It does have a stripe on the back of its neck, and a yellowish color. Even its posing on the telephone wires is indicative. Its call matches the one here.

I really feel good about this identification, and about sharing it:)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.