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Jack Aubrey Founder member
Joined: 31 Aug 2005 Posts: 513 Location: Camptoun, Scotland
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Posted: Sun Mar 25, 2007 5:53 pm Post subject: Waders and Hill-Goers |
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On the way along the Herring Road (or at least some of it - but that's another story ) today we put up a series of plovers and dunlins and such-like. It caused me to reflect that birds which divide their time between the shore and the hills must do so on the basis of the tides.
But how do they know what time low tide will be?
Puzzled Jack _________________ In the service of a Queen |
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Haggis Hunter Founder member
Joined: 29 Aug 2005 Posts: 2487 Location: The building site formally known as Edinburgh!
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Posted: Sun Mar 25, 2007 6:18 pm Post subject: |
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Not got a clue either, but perhaps they can sense the magnetic pull of the earth????? If that is how the tides actually work? _________________ Let me know if I say anything that offends you
I might want to offend you again later |
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Wildlifewriter Founder member
Joined: 04 Aug 2005 Posts: 948 Location: Norn Iron
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Posted: Sun Mar 25, 2007 10:17 pm Post subject: |
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If those plovers were of the golden type, my guess is that they are probably pairing up, looking for nesting sites, and generally getting it on - since it's coming up to that time of year.
Those Lammermuir Hills (sp?) are known as an important breeding site for waders, including golden plover, dunlin, curlew, and other like-minded articles.
-Wlw |
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HighlandNick Founder member
Joined: 30 Aug 2005 Posts: 635 Location: Highlands, Scotland
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Posted: Mon Mar 26, 2007 6:22 pm Post subject: |
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Clever birds...
They move around depending on a lot of factors, such as:
Availability of food
Weather
Tides
Seasons
Moon phases.....
Many migratory birds and homing pigeons have inbuilt compasses and also have been shown to navigate using the position of the sun. And salmon - their "noses" are very sensitive to "smelling" the water they were born in.
Now bees - there's an interesting subject - waggle dances........ |
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Tooey Member
Joined: 24 Sep 2006 Posts: 129 Location: Strathspey
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Posted: Fri Mar 30, 2007 5:25 pm Post subject: |
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I saw an interesting program on TV (now that is something rare these days). They had attached micro cameras to homing pidgeons and taken them to France. They were able to demonstrate that the birds were following major road networks to find their way home. |
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Crazy Druid Member
Joined: 25 Mar 2006 Posts: 188 Location: Edinburgh, Scotland
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Posted: Sat Mar 31, 2007 9:14 am Post subject: |
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Haggis Hunter wrote: | Not got a clue either, but perhaps they can sense the magnetic pull of the earth????? If that is how the tides actually work? |
You are half right...
All the water on Earth is affected by two forces of nature:
1) The gravitational pull of the sun and moon, and
2) The force (centrifugal) the earth applies as it spins (29.79 km/s).
The Moon is 400 times closer to the earth than the Sun so its pull is a lot stronger..
What does the pull of the moon (and the Sun) do to the water?
It creates two types of tides, high and low!
As the moon rotates around Earth, tidal bulges occur.
The bulge is really a large wave beneath the moon that moves across the earth. On the opposite side of Earth, there is a second bulge.
These bulges are high tides. There are usually 2 high and 2 low tides occur each 24 hours and 50 minutes (the time it takes for the moon to orbit Earth)
But...
Then you have Spring Tides and Neap Tides...
Spring Tides And Neap Tides
When there is a full (or new) Moon ,the gravitational pull of the moon and sun are combined and at t these times, the high tides are very high and at low tide the tide is very low. This is known as a spring high tide.
During quarter phases the sun and moon cancel each other as they are at right angles, this causes a smaller differance between low and high tide. This is called a Neap Tide..work at right angles, causing the bulges to cancel each other.
Last edited by Crazy Druid on Sat Mar 31, 2007 3:16 pm; edited 1 time in total |
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Firth of Forth Founder member
Joined: 29 Aug 2005 Posts: 1493 Location: East Lothian, Scotland
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Posted: Sat Mar 31, 2007 9:20 am Post subject: |
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Let's face it...these birds are clever creatures and have a variety of mechanisms to navigate with. If the conditions aren't right for using one, they have a backup system, or if they aren't sure about where they are, the can check using another system. Of course, sometimes they make errors or all systems fail and they end up completely off course. Sound familiar?
I can remember having to write an essay at University about bird navigation for the animal behaviour module - it was fascinating stuff. But I think a lot more is known now compared to 30 years ago when I had a go at the essay! _________________ Utterly smitten by a Captain
And now Mrs Aubrey |
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Crazy Druid Member
Joined: 25 Mar 2006 Posts: 188 Location: Edinburgh, Scotland
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Posted: Sat Mar 31, 2007 9:42 am Post subject: |
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Yep they are very clever, take the homing pigeons they can use the sun and the stars to take navagational bearings and they have some sort of in built compass...but once they have flown the route a few times...they follow the roads Its true..research has tracked them flying round a roundabout and taking the correct exit....Even turning at junctions
My uncle used to have loads of Pigeons and he spent many days telling me how clever his birds were and to see them come home after flying hundreds of miles was fascinating.
Some researchers even say that some diurnal birds fly AA-suggested routes even if it means the journey they fly is longer...
So I wonder if the saying "as the crow flies" is a lot more complex than the strait line that we are used to thinking |
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arock&ahardplace Member
Joined: 08 Sep 2006 Posts: 184 Location: Edinburgh
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Posted: Mon Apr 02, 2007 6:01 am Post subject: |
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Thanks for posting that bit about the tides, CD. I didn't know all of that. And your animations made it much more clearer. _________________ Remember: no matter where you go, there you are. |
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