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I figured it out! STOP PRESS! - Tactical Ninja

Feb. 10th, 2013

10:01 am - I figured it out! STOP PRESS!

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So you know how yesterday I mentioned that the flystruck ewe had tipped over into the resigned stage and that this is a thing sheep commonly do when sick? I've always wondered what kind of evolutionary advantage they gained from doing that - how does lying down and going "Oh woe I am going to die but I'll accept that gracefully, come get me predators..." is helpful to survival. Then I realised I was looking at it wrong.


Sheep survival depends on two things:

1. Flocking together - safety for sheep is in numbers because otherwise they are slow, defenceless and tasty.

2. Being prolific. They can produce and rear offspring in remarkably adverse conditions, and multiple births are common.

We're looking at number 1. Sheep hang out together - even when they aren't disturbed, they'll distribute themselves so they can always see at least 2 or 3 of their flock mates. They only go off by themselves to lamb, and even then another sheep will often stay within sight of both them and the flock, acting as a sentry.

When a flock is threatened, they all mob together tightly. The ones in the middle are safest and the ones on the outside press towards the middle. When approached closely, they scatter like a school of fish and then flock together again at a distance. I think this is confusing to predators, and means that the relative chance of being grabbed decreases as the size of the flock increases.

Anyway, an important part of this flocking behaviour is Not Standing Out. Those that stand out are more likely to be grabbed, especially if they show some sign of weakness. Predators are always on the lookout for easy prey. So, if a sheep is sick, it'll hide it as much as possible. Remember yesterday's sheep, and how subtle the signs of illness were? And she was pretty close to keeling over.

So instead of looking at the 'resigned' stage as an evolutionary advantage, what I should be looking at is the way in which sheep hide their illness until they are so far gone they can't stand up any more. THAT is the evolutionary advantage, because that is what will help a sheep that's sick but going to pull through to survive in a flock - to not stand out for predator-grabbage, to be taken on casual glance as healthy.

And when they fold (which is the terminology for lying down and going WOE IS ME), they really are completely exhausted and possibly close to death. It's not an illness-response, it's an inability to produce the illness-response any more through having used all their reserves hiding their illness.

Gosh, sheep are a lot like people.


Yes, that really did keep me up last night.

*ahem*

Comments:

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From:ecosopher
Date:February 9th, 2013 10:34 pm (UTC)
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Sheep ARE a lot like people. I always feel so very sad when they get to that stage. Geez, flystrike is a nasty thing.
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From:tatjna
Date:February 10th, 2013 01:18 am (UTC)
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It really is. It's kind of the extreme end of horrible things that can happen to livestock I reckon, and I'm really glad it's so easily treated if you catch it in time.
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From:raincitygirl
Date:February 10th, 2013 12:09 am (UTC)
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Well, I found it fascinating, and I don't even like sheep.

I don't dislike sheep either. I just have no great interest in them one way or t'other, or didn't until I read this.
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From:tatjna
Date:February 10th, 2013 01:19 am (UTC)
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Eeeeee, I'm glad you found it interesting. I'm kind of accustomed to the eyerolls that go along with my sheep geekery, but I'm surprised by how many otherwise-uninterested folk seem to enjoy when I ramble about sheep on the internet. ;-)
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From:raincitygirl
Date:February 10th, 2013 01:22 am (UTC)
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Your ramblings don't make me want to run out and become a sheep shearer myself (especially hearing how much they weigh and how athletic a job it is), but I really enjoy hearing about something that's so alien to my own experience. Where else would i learn about sheep survival mechanisms?
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From:tatjna
Date:February 10th, 2013 01:27 am (UTC)
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I haven't yet met anyone who's been inspired to become a shearer by my blog. ;-) But I am working on convincing as many sheep owners as I can to learn for themselves!

(not that i've had any luck with that either)
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From:richaarde
Date:February 10th, 2013 01:13 am (UTC)
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It's actually not unusual for any animal to "grin and bear it." Predators do it as well as herd animals - even domesticated dogs and cats will bear it as long as they can.

They do this because if they appear weak, they themselves can become prey. It's better to pretend that nothing's wrong than it is to become dinner to another predator.
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From:tatjna
Date:February 10th, 2013 01:17 am (UTC)
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This is true. But sheep are exceptionally good at it.
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From:kehleyr
Date:February 10th, 2013 01:39 am (UTC)
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I found it interesting too :-).
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From:tatjna
Date:February 10th, 2013 03:58 am (UTC)
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Thank you, I'm glad. ;-)
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From:meathiel
Date:February 10th, 2013 12:39 pm (UTC)
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I have to admit I know next to nothing about sheep - this was very interesting!
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From:pundigrion
Date:February 11th, 2013 09:08 pm (UTC)
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Birds do this too. They are masters at hiding being sick until they keel over. If you know what to look for you can see a sick bird quickly, but even then they are often very ill by that time!
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