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RE: NFC: Re: Fishy Behaviour

First, bears also kill cubs, nothing to do with
bringing sows in heat, they just kill them to eat
them.They are on the menu du jour. Wolves will kill
young of strange packs, territory thing.

Boar Raccoons will do the same. etc etc

Re: African Lions, the statement "male lions kill the
cubs of a new pride to bring the lioness's in heat"
presupposes the male knows the cause and effect
relationship. That is extremely implausible, I have
never known of any big cats to have operative
knowledge of genetics and physiology. 

I have no idea why, my guess is it would be more a
matter of strange odor, or a matter of temperament and
just lacking any parental nurturing feelings towards
the cubs. Lioneness's introduce cubs to the pride,
males included, if he acts hostile she reacts hostile,
he has an opportunity to become acclimated to the
cubs, and accepting them, in the case of a new 'boss'
male taking over, there is a LOT of hostility, and in
the ruckus of the time involvement its everyone on
their own on a survival basis, under the
circumstances, the cubs having no survival preparation
are on the short end of the stick and become first
casulties after the dominant male succumbs. Then the
females stop lactating and that brings them back in
heat after a time to come back into condition to bring
on estrus.As with fish, conditioning brings on

We have been seeing a lot of opinions on the male
eating the eggs thing that is doing some of this same
kind of assuming superior knowledge of the fish and
that their actions are to 'get more energy' and
attributing various thinking and reasoning processes
that are highly unlikely. Lets not try to make little
people out of them, they are fish with their own cause
and effect behaviors. True, the behaviors have various
implications in survival, either negatively or
positively, but, its within the parameters of fish
behavior not some higher system of reasoning.   

Delayed implantation,or development, seems to be more
common among cervids and marsupials and is an actual
environmentally induced process. Among most cervids
wherin it occurs the bodys metabolism drops
significantly to a bare survival rate to conserve
energy, during this time there isnot sufficient
resources to enable development of a fetus, so the
development is put actually on hold until spring
brings on sufficient foodstuffs to support the
developing embryo. In marsupials it is similar except
is triggered by drought. WHen rains come the embryo
develops to the fetus stage and normal development.
Interestingly, this may be one of several embryos
developing in turn in a sequence.

Study, quiz monday,
--- "Denkhaus, Robert" <DenkhaR at Ci_Fort-Worth.TX.US>
> chris at yonderway_com wrote: 
> >>       > Very few land dwelling species eat their
> own 
> >>      >  young and I am not aware of any that do
> it to 
> >>      >  the degree that fish do.
> >>
> >>
> >>   Lions do.  At least the males of the species
> anyway.  
> >>  You think HUMAN males think with their
> genitals... male 
> >>  lions will eat the young lions to cause the
> female to 
> >>  come into heat again.
> >>Doug Dame wrote:
> >>That's a partial story as I understand it. When
> new males move in and take
> over an existing pride by driving off the males of
> "the >>former regime,"
> they have been then observed killing off the
> existing cubs ... which aren't
> theirs, of course. This has the effect of
> >>eliminating the genes that
> aren't directly theirs and also (as you say) brings
> the females back into
> heat faster than they would have >>otherwise, which
> is presumably the
> Darwinian double-bonus that makes such behavior
> advantageous to the genes of
> the perps. 
> >>
> >>I don't recall having heard they "eat" the young
> as we'd commonly
> understand that, nor that it happens under any
> circumstances >>over than new
> regime of bullies deposes former of regime of aging
> bullies.
> Male lions do not typically feed upon the young
> after they kill them which
> seems to prove that they are not killing for
> sustenance and from my
> knowledge of lions (gained primarily from several
> years as an education
> curator in the zoo world) it is accepted that cubs
> are killed simply to
> bring the lioness back into estrous.  Also, and I am
> not sure how someone
> might want to fit this into the discussion, don't
> forget that many mammals
> have the ability to "manage" their pregnancies. 
> Embryos are often
> reabsorbed in times of environmental stress, i.e.
> food shortages, droughts,
> and even overpopulation in some cases.  Some
> mammals, primarily mustelids
> (weasel family) if my mammalogy memories serve me,
> also practice delayed
> implantation and frequently delay the fertilized
> egg's implantation
> indefinitely when times are tough.  Delayed
> implantation explains many
> "miracle births" that occur when a female has not
> been exposed to a male for
> a period of time longer than the gestation period. 
> Assuming that fish do
> not have the ability to manage their reproduction in
> these ways and simply
> are at the mercy of an instinct to produce young
> whenever and wherever
> possible would (could?) explain why many fish take
> advantage of the
> nutritional value of their own spawn.
> Someone also mentioned that birds don't typically
> eat their own young and
> while this may be true, fratricide, where one or
> more members of a clutch
> kill and sometimes eat their siblings, is relatively
> common in the avian
> world. This could also be considered a form of
> Darwinian selection or a
> simple population control measure if not utilization
> of available food
> resources.
> Rob Denkhaus
> Fort Worth Nature Center & Refuge

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