Author Topic: Hornby Ground Observations That Aren't Eagle Related... 2011-2012  (Read 194778 times)

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Offline emc

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Re: Hornby Ground Observations That Aren't Eagle Related... 2011-2012
« Reply #525 on: September 19, 2012, 10:16:10 AM »
 :mhihi. Sorry about trying to drown your camera.

Wren, you might consider Glaucous Gull for the Gull.   The oystercatchers are very beautiful!  The contrast colors are stricking!
beth
from California

Offline madrona

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Re: Hornby Ground Observations That Aren't Eagle Related... 2011-2012
« Reply #526 on: September 19, 2012, 02:36:57 PM »
It's always so interesting reading here.  The photos are great wren - love the oystercatchers.

The gulls in your last photo looked like Herring Gulls to me - the ones we often see around here (or maybe hybrids?).  Not that I have spent a lot of time studying gulls!  :ecrolleyes   Check Here! and photo below.



Eeeeek - is that fishing line in that picture?

   Wildness reminds us what it means to be human, what we are connected to
      rather than what we are separate from. - Terry Tempest Williams

Online Cawatcher

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Re: Hornby Ground Observations That Aren't Eagle Related... 2011-2012
« Reply #527 on: September 19, 2012, 02:53:44 PM »
 :sigh Sadly yes fishing line Madrona.. The Photo of the gull and shell is great!

Offline gzebear

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Re: Hornby Ground Observations That Aren't Eagle Related... 2011-2012
« Reply #528 on: September 19, 2012, 04:16:47 PM »
Great photos, wren!

I'm sorry to question your source*, madrona, but Herring Gulls that I have seen have black wing-tips. I think those are more likely Glaucous Gulls.

*he uses the same photo for two different gulls

Offline madrona

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Re: Hornby Ground Observations That Aren't Eagle Related... 2011-2012
« Reply #529 on: September 19, 2012, 04:34:03 PM »
Great photos, wren!

I'm sorry to question your source, madrona, but Herring Gulls that I have seen have black wing-tips. I think those are more likely Glaucous Gulls.

My source did say that, gzebear. 

Quote
The adult Herring Gull is about 61 cm long from the tip of its bill to the tip of its tail. Its head, body, and tail are white, its bill is yellow with a red spot on the lower tip, and its legs are pink or flesh-colored. The backs and upper wing surfaces of adult gulls are grey, and the tips of their outermost flight feathers are black with a white spot.  http://www.askbud.ca/herring_gull.htm

I think at least one of the gulls in wren's pics had dark wing tips - also, at least two of them had paler eyes, unlike the dark eyes of the Glaucous.  I strongly suspect that these are hybrids. 
   Wildness reminds us what it means to be human, what we are connected to
      rather than what we are separate from. - Terry Tempest Williams

Offline gzebear

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Re: Hornby Ground Observations That Aren't Eagle Related... 2011-2012
« Reply #530 on: September 19, 2012, 06:33:31 PM »
Okay, I really don't know all the gulls, just the ones we have here. And not to argue, but just saying ... on one page he calls these gulls Western Gulls, on another page he calls the same gulls Herring Gulls ...




Offline winterwren

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Re: Hornby Ground Observations That Aren't Eagle Related... 2011-2012
« Reply #531 on: September 19, 2012, 07:52:33 PM »
Those Larus gulls are so complicated to tell apart, I'm almost sorry I asked.

Herring Gulls have pale pupils and dark wing tips.
Western Gulls' eyes range from pale to dark, but they have a yellow-orange orbital ring, and they also have dark wing tips.

Glaucous-winged Gulls have pale eyes, a bright-yellow orbital ring, and very pale wing tips.
Glaucous Gulls have medium-pale wing tips, dark eyes and a pinkish gape.

Based on that, these gulls on my picture are probably hybrids. All the Larus gulls interbreed, which greatly adds to the confusion.

What caught my eye is the bill colour. Maybe all the big gulls get paler bills with their non-breeding plumage, and I never noticed?

Last week I spent a day on the water with people who made me rethink my "oh, it's just another gull" attitude. I had probably run into those beautiful red-billed Heermann's Gulls a bunch of times, and never noticed. So now I'm probably asking too many questions.  :eclol

Offline emc

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Re: Hornby Ground Observations That Aren't Eagle Related... 2011-2012
« Reply #532 on: September 19, 2012, 09:09:34 PM »
No wonder I can't learn the gulls.

Some excerpts from one of my sources: Field Guide to the Birds of North America National Geographic:

Glaucous Gull:  yellow eye, translucent tips of white primaries

Glacous- winged Gull: eyes dark, primaries same color as rest of wing

Most of the gulls with red dot on yellow bill have white dots on dark tail in pictures except these two.

I have given up trying to ID gulls , lol.
beth
from California

Offline boonibarb

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Re: Hornby Ground Observations That Aren't Eagle Related... 2011-2012
« Reply #533 on: September 20, 2012, 09:32:27 AM »

i got an excited e-mail report from a friend who*d gone out kayaking last evening!
She writes -

Today i wish I had your camera 'cause then i could be showing you
instead of telling you about the flock of sandhill cranes that flew
overhead as we were out kayaking this evening.!
They hung out on Dunlop Point beach for a while and then took off again, just
fantastic.  First you think it's Canada geese but they don't look right,
then you wonder why are all these herons flying in formation?
then they start calling out and it's a sound you've never heard before. 
I almost capsized in my excitement to get out my binoculars!
Amazing, here, on Hornby! Cranes!
wow
wooohoooo!

Offline cinnemon

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Re: Hornby Ground Observations That Aren't Eagle Related... 2011-2012
« Reply #534 on: September 20, 2012, 10:34:40 AM »
Booni I have only seen them in Florida when visiting, didn't know they were anywhere else. I would have loved to be able to see them like you did!

Offline winterwren

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Re: Hornby Ground Observations That Aren't Eagle Related... 2011-2012
« Reply #535 on: September 22, 2012, 09:46:47 AM »
During the second week of September, a group of biologists and biology students was on Hornby for a research project on the Harlequin Ducks. Through my wonderful family connections I was invited to volunteer. Unfortunately I was working most of the week, but on the last day I was able to join the group, and help out where I could, and also observe, take photos, gawk, absorb new knowledge like a sponge, wonder, and enjoy a beautiful day on the water with people who can identify seabirds, genus and species, a quarter mile away, people who are used to long patient days in the field and longer patient days in the lab. For me, there is nothing and no one better.

Emily Missyabit MacAuley was the project leader; this study is part of her doctoral thesis. She has given me permission to write about her work here and to post the photos I took on that day.

First of all, for those who don't have the good luck of seeing them daily, here's what an adult male Harlequin looks like...
October 31 2011, Grassy Point (Click all photos to see larger sizes)



Here's my understanding of how Emily's thesis goes. I'm hoping that if any of the team read this and see any big gaps or mistakes, they will post a reply or email me so I can correct my facts.

When I was hiking up the Joffre Lakes trail a few weeks ago (see the story starting with This posting), I saw someone fishing for trout in the Middle Lake. I was wondering how the trout had gotten there, at 1600m of elevation, over miles of impassable cascades. Answer: humans brought them. The lake is seeded.
It's like that all over British Columbia, and probably the whole continent. Every major stream that didn't already have trout in it has been seeded, and an amazing number of alpine lakes as well. Pete Clarkson, from the National Parks services, who worked on the harlequin project, told me that people used to take pack horses with special containers up the trails all over the Rockies and carry trout fry to the streams and lakes.
The most extreme example I know of is Yellow Lake, near Penticton. There had been attempts to seed that lake since 1940, but the fish always died. This is because the lake is sulphurous, and poor in oxygen at certain times of year. This lake probably held a very unusual ecosystem... But no matter. In 1969, aerators were installed to increase the oxygen content so that the introduced trout could survive.
Beautiful. So I can take a fly rod anywhere and catch a fish. Well, I do like fish, and I enjoy fishing, so where's the problem?
Tigerlady uses this quote from John Muir as a signature at the end of her postings, so you'll find it familiar: "When one tugs at a single thing in nature; he finds it attached to the rest of the world." That is, in essence, the problem.
Emily's thesis is about the impacts of the trout on the Harlequins' health and reproductive success, and by extension it questions the wisdom of seeding trout all over the landscape.
Harlequins gather in great numbers around Hornby Island in the winter, but in the summer most of them disappear to breed on inland streams. They make their nests on the ground under low shrubs, or on the cliffs of river canyons. They are not fish eaters; they eat invertebrates, some of which are also the diet of the trout.

When there are trout in the streams, the invertebrates behave differently. Some become a trout's breakfast, others hide or move in different ways. Emily is asking whether this makes them less available to the Harlequins and whether this, in turn, influences the Harlequins' health and reproductive success.

So, why is she catching ducks on the coast then?

First, she did go study ducks directly on the streams. But here on the coast, in the Harlequins' precious gathering grounds, it's easy to find a lot of birds in a short time, and some astonishing research methods allow the team to retrieve information about the breeding grounds, information that has been stored right into the birds' bodies.

Harlequins return to us in late August and early September. As soon as they arrive on salt water, the adults moult all their flight feathers and are flightless until the new set grows out - about two weeks.
The males arrive first. By the time of the study, they were able to fly again. The females arrive a bit later, and were flightless during the study. The juveniles come back with their mothers (a previous study by Heidi Regehr has demonstrated this), but since the youngsters just grew their first set of flight feathers on the nesting grounds, they don't moult and they retain their ability to fly.

Now comes the woo-woo stuff.
There is a group of minuscule somethings called 'stable isotopes' that persist in the body tissues of the ducks (and of every living thing, if I understand correctly) from the food that they eat.  Many of us learned about radioactive isotopes in high-school chemistry class; stable isotopes, too, are variants of a given chemical element, but they are not radioactive. The proportion of different stable isotopes in a given part of a bird's body corresponds to the proportion of the same isotopes in the food source that made that part of the body grow. It's as if each part of the body bore the fingerprint of the food sources that formed it. The stable isotopes persist for different lengths of time in different tissues, since the cells that form those tissues have different turnover rates.
In blood, the stable isotopes persist for about 2 weeks; in claws, a month? several months? something in that range; in feathers, for as long as the feather exists. In feces, the stable isotopes give the fingerprint of the site where the bird ate today.

Now get this. The ratios of stable isotopes from streams with trout are different from those of trout-free streams! So, somehow, the presence of trout in the streams alters the very chemistry of the invertebrates in that stream, and this alteration can be measured in the cells of the Harlequins who eat the invertebrates.

So far, so good? I'm a bit fuzzy on that stable isotope stuff, but a general idea is enough to grasp the gist of the study.

So, back on the waters around Hornby Island, the group captured unflighted Harlequins into traps. The males already fly and the youngsters never quit flying, so the captives were all adult females. Then on different days, they used nearly invisible floating nets (mist nets) to catch flighted birds that did not have the adult males' colourful plumage.  So, those are the juveniles born this year.

The fecal samples (okay, we just collected the stuff when they pooped on us...) will contain the stable isotopes corresponding to where the ducks ate today. Emily collected some seaweed from the mist nets to serve as a baseline, a fingerprint for the marine environment around Hornby, and in theory, the isotopes from the feces should match that.
In the blood samples, the stable isotopes of a given feeding site persist for two weeks. So the females and young, who have been here between one and two weeks, should have some of the markers of their nesting grounds persisting, and some new markers of the marine environment also.

In the claw samples, the stable isotopes persist for a month or a few months (I forget... Something in that range. Think of the claw as growing out, like a minuscule fingernail, and getting worn out at the end.) So the claw samples would show the stable isotopes from the nesting grounds.

The feather samples hold stable isotopes from the location where they grew. So the youngsters' feathers would all bear the fingerprint of the food they ate at the nesting grounds.
The feathers of the females grew wherever they last moulted, which is probably on the coast. (I'm assuming here that the body feathers moult on the coast, after the flight feathers.)
There is one exception, though: if a given female incubated a clutch of eggs this last summer, she developed a brood patch. The feathers that now cover the brood patch regrew at the nesting grounds. So, if the belly feather sample matches the fingerprint of a freshwater stream, it means that this female had a clutch of eggs. If the sample matches the coast, she did not develop a brood patch this year. So in theory we should be able to tell if she nested... And whether she nested on a trout stream or a trout-free one!
Isn't that clever?

The different samples, through some more magic in the lab, also give information about the rate of growth, i.e. the abundance of food.

So that's the theory. The results, of course, will only become clear after long weeks in the lab. So meanwhile in the next few postings I'll show photos of what we did on the water on September 13.


 
« Last Edit: January 04, 2019, 10:32:12 PM by winterwren »

Offline winterwren

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Re: Hornby Ground Observations That Aren't Eagle Related... 2011-2012
« Reply #536 on: September 22, 2012, 10:18:19 AM »
So, here, Emily is with Pete Clarkson, a longtime Parks Canada ranger who was among the first to sound warnings on the vulnerability of the Harlequins' inland nesting sites. Pete and Emily are setting up the mist net. It's a simple and clever setup, with the added goofiness of the floats being disguised as Harlequin decoys. Right up my alley. Each post rests on crossed metal bars; each bar end with a float. Here, the net itself is still in the bags hanging to the middle post. We have set up an anchor on shore and Emily is preparing to drop another anchor at the far end.
(All pictures are clickable.)
September 13,  11:29 am



A few final adjustments...
11:49



The completed net setup. We've anchored more decoys, these ones a bit truer to life, on both sides of the net. We're hoping that the young Harlequins, when we disturb them, will fly to the safety of numbers and will not mind if some of those numbers are made of plastic.
11:49


We leave someone on the beach to watch, and we go hunting, hoping to flush groups of youngsters toward the net.

There have been a few previous studies on Harlequins here, and the most recent one, by Heidi Regehr, showed that the small groups of brown birds we see at this time of year are actually broods: a mother and her three or four babies. So that is what we are now looking for. The females cannot fly but the youngsters can. From a distance, they otherwise look identical, except to the wickedly keen eye of my expert companions.

We got skunked at that first site, near Shingle Spit, and moved north to Collishaw Point, near Nests 6-7. There we set up the net again.



Offline winterwren

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Re: Hornby Ground Observations That Aren't Eagle Related... 2011-2012
« Reply #537 on: September 22, 2012, 10:57:09 AM »
Caught!!!

September 13, 2:47



Poor dear, he's really tangled.
2:47


It took a while to get him out, cautiously and gently, but he was not hurt. Another youngster hit the net at the same time, and a third one shortly after.

When catching unflighted birds into a trap, it's easy to get a dozen, but the flighted youngsters are much more difficult, and my companions seemed happy enough with those three.

We moved to processing the birds as soon as it was apparent that no others were in the immediate area. There are guidelines that ensure that the birds do not spend too much time in captivity. We put the little darlings in cat carriers, just as we would for birds bound for rehab. Then we found a safe place to anchor the boats on the rapidly rising tide, a place with good light for the finicky work we had to do but shady spots for the waiting birds.

All three of them turned out to be males.
Apparently the dark eye ring on this fellow is the very start of his adult plumage.



Here's a photo of a female I took at Norris Rock a couple days ago, for comparison. I assume she was a female... She was hanging out with a guy.  :mhihi

The pattern of whites and darks around her eye is indeed different.
September 20, 3:49 pm



Offline winterwren

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Re: Hornby Ground Observations That Aren't Eagle Related... 2011-2012
« Reply #538 on: September 22, 2012, 11:17:24 AM »
So now we start collecting information.

Measuring the tarsus length...



You can see yellow on the duck's foot... Another marker of a juvenile. Females have all-grey feet if I remember well (I'll have to double-check that.)


Measuring the culmen...




We also measured the wings, but I didn't get a good photo of that.

Weighing... (Willow is doing all the hard work.)




Here Emily is collecting feather samples from one of the birds. After this she will collect tiny claw clippings (she will actually use a nail clipper to do this) and blood samples from a vein on the inner wing.




Offline emc

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Re: Hornby Ground Observations That Aren't Eagle Related... 2011-2012
« Reply #539 on: September 22, 2012, 11:24:28 AM »
Fascinating research. The slightest thing man does to change nature ( seeding trout, years ago! Seemed like a very good thing) upsets the balance somewhere else.
beth
from California