Why do some animals leave to go and die?

[SmoothOperator]

I have known several animals that disappeared when it came time to die. I have seem it a few times. One neighbors dog came over to our house to die under a lilac bush we had when I was young. Our neighbors cats and now my dog has done the same, but we don't know where they went. I was just wondering why? Why go off instead of dying near your loved ones?

[DrMatrix]

WAG:

Since dead bodies tend to grow all sorts of nasties, in the wild it is healthier for its loved ones if an animal leaves to die.

[ultrafilter]

Although I'm not sure whether he's correct or not, DrMatrix's theory does require selection pressure on a gene that determines an animal's behavior after reproductive age. So it's possible (within the "selfish gene" framework put forth by Dawkins), but probably unlikely.

[SmoothOperator]

Is it something that wild animals do too? I mean if you were looking into the dynamics of pack animals, do the sick and/or dying ones leave the pack to go off and die somewhere all alone?

[Triskadecamus]

Doc,

Of course, in a behavioral sense, the animal has some other reason, which has been preserved over generations because its close associates share nearly the same genetic make up. Perhaps the animal's dying body creates chemical messengers that make the familiar scents of home disturbing, or unpleasant, causing it to seek entirely new habitat. Those which shared the habitat of individuals which had the physiological characteristics causing the animal to distance itself from its home during its final hours benefited from that absence, and were more successful in producing offspring. The animal dies, and its descendants and near relatives gain the benefit of its "sacrificial" act.

The animal itself does not know about the hygiene benefits, or the increase in probabilities for genetic selection. Even though the trait is not beneficial for the individual, it does benefit its species, and directly favors its most close associates, who are likely to have similar genetic characteristics.

It is always important to avoid the implication that evolutionary processes are intentional, on the part of the species or individual itself. Although each individual is trying to survive, it is not making plans for the survival of its species. It might have behavioral patterns that accomplish that, but it is loose thinking to say that it does so in order to accomplish that aim.

Tris
------------------------
"What have you done to that cat? It looks half dead!" ~ Mrs. Erwin Schrodinger ~

[jimmmy]

Often Animals that are sick or injured will go off to a quiet place to hole up (literally) to rest and hopefully recuperate. If they live, we say they just wandered off and came back, if they die then it seems they "knew" they were dying and went off to die.

Think of it like going to the hospital, most folks aren't going there to die, they are going there to hopefully recover ... your lilac bush was/could be seen as the dog's version of a "hospital".

[jimmmy]

Here is an Animal Doctor Column that completely agrees with and completely contradicts my previous post (3rd answer).

Doc's is talking outta both sides of his mouth IMHO.


http://www.washingtonpost.com/wp-dyn/articles/A19005-2002Jul29.html

[Babar714]

I always heard that the elphant is the only wild animal proven to seek out a 'dying ground.' Is this true?

[mmmiiikkkeee]

I beleive old sick gorillas will often go find a hollow in a tree trunk and curl up there, sometimes dying - which can make their bodies hard to find for researchers... then again some will be found dead (of natural causes) right out in plain sight. A lot of sick or dying social animals seem to at least distance themselves from the rest of the group when their time is near; maybe something to do with not wanting to show weakness and/or slip even further down on the social pecking order during their last few weeks or days.

Then again do even all humans like being around others when they're hacking up plegm, throwing up, or hobbling around in obvious pain? There's an elemnet of pride and self-conciousness for us involved, perhaps something similar exists for animals.

[Ringo]

Babar, I don't think a true "elephant graveyard" has been found.

[The Flying Dutchman]

Originally posted by Babar714
I always heard that the elphant is the only wild animal proven to seek out a 'dying ground.' Is this true?

No, it has been established beyond ant reasonable doubt that salmon return to the place of their birth when their time is up. They will travel thousands of miles to do so.

When ever we see or hear of an incident of a sick animal withdrawing and isolating itself from the herd/pack, it's my WAG that such animal is seeking refuge in order to recuperate in the safest possible environment that it perceives. There is no security with the herd/pack for the weak as the predator well knows.

[SmoothOperator]

So you are saying that the weak or sick delibrately takes itself away from the pack, not in order to protect the pack from the stench of decay and the hordes of predators that smell would attract, but in order to protect itself from the others in the pack.

[The Flying Dutchman]

No, but the herd offers protection in the open for its members who can keep up. Sheer numbers offers probability for a member of a herd not to be selected as a prey. However the stragglers in the open become a prime target. Better to go and hide somewhere.

In the case of a predatory pack animal , which usually requires a great deal of energy to continue to participate in the hunt, it would be better to find a a secure and quiet place to recuperate rather than be left behind in the open, subject to other predators.

I won't rule out the suggestion that it might also be a result of pack dynamics. A sick pack animal might become the omega of the group subject to harrassment from the rest of the pack.

[The Great Philosopher]

Among smaller animals this characteristic is often observed: it's widely thought that this is to prevent the animal from being easy prey for its predators while it is weak, then it can return to its normal habitat once it has (hopefully) recovered.


This theory may not apply to dogs and cats, however: wild dogs live in packs, so any large predator that attempted to chase a pack of dogs with intent to 'make a kill', as it would for a herd of antelope, would probably be met with dozens of sharp teeth, rather than terrified flight. Thus the sick dog would have protection from its healthy buddies. This theory is made even more unlikely by the fact that an ill dog could stay with its pack and leech food from them, but by wandering off, it might seal its fate.

Cats however may still retain this instict from long ago: being a sole hunter, a weak or sick cat would be an easy meal (be it not particularly large) for virtually any predator bigger than it.

Just presenting a theory. :)

[David Simmons]

Originally posted by grienspace


No, it has been established beyond ant reasonable doubt that salmon return to the place of their birth when their time is up. They will travel thousands of miles to do so.


But salmon are going up their original stream to breed. They die because their chemistry, as adults, is suited to salt water that is slightly more concentrated with salt than their body's fluids. Therefore they slowly lose fluid to their surroundings in the sea and have to drink water to replenish it. In fresh water, the reverse is true. Their body fluids are a lot saltier than their surroundings. Fresh water floods their system, diluting their body fluids and upsetting their chemical balance. They only survive long enough to breed and then die, but that isn't why they came to that place.

[The Flying Dutchman]

David, then please explain the life cycle of the Kokanee salmon, essentially closely related to the sockeye, but landlocked from the sea. Their entire life is spent in fresh water and spawn once at either 3 or 4 years of age, whereupon they die within several weeks. See http://www.gmfsh.state.nm.us/PageMill_TExt/Fishing/kokanee.html

cite
Closely related to the sockeye salmon, the kokanee salmon is a smaller version of its widely-known, rosy-fleshed cousin.... Eons ago, due to shifting land masses, erosion, and other earth changes, certain sockeye populations became landlocked in freshwater lakes from which river outlet had been diverted or otherwise eliminated.... In New Mexico, kokanee spawn at 3 and 4 years of age, September through January. Although kokanee no longer travel from the sea to river headwaters, they still retain a strong homing instinct. Spawning adults will normally return to the site where they emerged as larvae or even where they were stocked, if they are of hatchery origin.

The peak of kokanee spawning varies from year to year, from lake to lake. Spawning occurs in gravel riffles of streams and in shoreline pebbles of lakes. The female builds the nest and covers the eggs with small gravel after they are deposited and fertilized. Kokanee spawn only once during their life cycle. After spawning, kokanee live only a few days to a few weeks -- the time of year when kokanee are most easily caught by snagging.

[mmmiiikkkeee]

Salmon will even deteriorate physically to the point of death after a set number of years even if they never see a change in salt/fresh water at all; they definately have a limited number of years and that's it, even if they are perfectly healthy and have lots of food/no disease. And yes, once they mature sexually and start ripening up, it's their sole intent to make it to their breeding grounds, spawn, and then defend their nest site until the end... dying just happens to be part of breeding for most salmon.

So these animals at least certainly aren't hobbling away to die alone; quite the opposite - they are all howling at the moon, high as kites from starvation and exhaustion, and racing ahead in mass for their one and only gigantic orgy back home!!!

[David Simmons]

Originally posted by grienspace
David, then please explain the life cycle of the Kokanee salmon, essentially closely related to the sockeye, but landlocked from the sea. Their entire life is spent in fresh water and spawn once at either 3 or 4 years of age, whereupon they die within several weeks. See http://www.gmfsh.state.nm.us/PageMill_TExt/Fishing/kokanee.html



The point isn't whether or not the chemistry of ocean salmon is the same as related fresh water fish, but whether or not the purpose in ocean salmon returning to their home waters is to die. I don't know why the Kokanee dies after spawning. That's just one of the multitude of things that I don't know and it has nothing to do with the matter at hand.

In this discussion the Kokanee salmon is just a red herring.