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 Post subject: Re: Antelope: Impala
Unread postPosted: Wed Jan 20, 2010 6:07 pm 
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I've heard from numerous guides that they can hold the birth of their fawns for at least a month.

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 Post subject: Re: Antelope: Impala
Unread postPosted: Wed Jan 20, 2010 8:28 pm 
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Nobody actually asked the Impala, It could be a number of reasons,

Rain Cycle, previous cycles thinning out the males, a male in a territory having all the gals, predation stopping birth(IMHO they can delay the birth), mixture of sexes in an area, so IMHO, no fixed theory. :thumbs_up:

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 Post subject: Re: Antelope: Impala
Unread postPosted: Wed Jan 20, 2010 9:39 pm 
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Impala cannot delay their birthing date

Imberbe wrote:
:naughty:

No guys ... Impala cannot delay their birthing date! That is a (persistent) myth! Think about it ... should the mother delay the birth for say three weeks, how big will the lamb have grown in that extra three weeks? How many females will die, because the young are too big to be born?

Impala are short day breeders with a restricted mating season in autumn. The peak of the rut varies by up to 20 days year on year, as it is influenced by the lunar cycle. This means that the date of conception varies. This has a direct bearing on the birthing date, which is 194 - 200 days later. (See Mammals of the Southern African Subregion - J.D. Skinner and C.T. Chimimba, Cambridge, 2005)


We saw baby impala last year in Kruger before the rains came.

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 Post subject: Re: Antelope: Impala
Unread postPosted: Wed Jan 20, 2010 10:11 pm 
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:D and "my" white Impala
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I think is the same, around Shingwedzi on the 24.10.09

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 Post subject: Re: Antelope: Impala
Unread postPosted: Thu Jan 21, 2010 8:28 am 
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Imberbe wrote:
What we have here is a typical situation of where a piece of "knowledge" gets repeated time after time, and then becomes accepted as "the truth." Which it isn't. :doh:


And that is one of the things wrong with the internet, and with a site like Wikipedia. Because everybody "knows" this to be true, it is accepted when it is posted, and not corrected. And the myth is perpetuated.

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 Post subject: Re: Antelope: Impala
Unread postPosted: Thu Jan 21, 2010 10:22 pm 
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Just remember that there's a difference between "variance" and "being able to hold back." Smithers says the gestation period is 194-200 days. Now, as with humans, you're going to get some that are slightly out of that range. Some will drop a bit sooner, and some a day or so later. That's not to say that they're planning that and doing it on purpose - it's just the say things are. Stress, drought, etc. - there are factors that may cause earlier drop and even abortion. But holding back...

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I believe that for man to survive, we must work with nature rather than against her. We need the land; the land doesn't need us. Too many people have lost sight of this fact. - Bruce Truter


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 Post subject: Re: Antelope: Impala
Unread postPosted: Fri Jan 22, 2010 8:50 pm 
Just to clarify...

The earlier posts about impala still being pregnant after rains has nothing to do with the "holding back" theory...

Two separate issues! :P


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 Post subject: Re: Antelope: Impala
Unread postPosted: Fri Jan 22, 2010 8:55 pm 
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I still believe they can hold back a few hours if the danger to the little ones is close, but just my personal opinion. :whistle:

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 Post subject: Re: Antelope: Impala
Unread postPosted: Sat Jan 23, 2010 11:46 am 
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Location: Cumbria/Northumberland border, UK
Richprins wrote:
Another fact is that a herd of females will drop their calves almost simultaneously, given a day or two!

And once again, this is not only confined to Impala! :P


Not an Impala expert by any stretch of the imagination but could that not be because female animals that live together tend to come into oestrus together, I know that most domestic animals do and so do humans, this is why flocks of sheep all lamb together.

I have no idea if it is true but I also believe that a female giving birth causes other females to go into labour. I believe it could be a hormone indiced reaction as a female in labour and soon after birth will have a surge of the hormone oxytosin (this helps her to bond with the newborn), now when I worked on a comercial pig unit this was the same hormone we used to induce labour in the sows.......

If anyone knows better please feel free to correct me :lol:

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 Post subject: Re: Antelope: Impala
Unread postPosted: Sat Jan 23, 2010 9:58 pm 
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It would be interesting to find out if there has been any research done as to which female gives birth first, I suppose it could be the most dominant females first, or the least dominant (which would make sense as any predators in the area may well kill the offspring of the 'lower' female first giving the more dominant females a better chance initially). Or of course it could always just be random..........

Would make an interesting research project for a student if it hasn't been done before (right I just need to find a degree that would mean I could do that as my dissertation :lol: )

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 Post subject: Re: Antelope: Impala
Unread postPosted: Sat Jan 23, 2010 10:53 pm 
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:hmz: I think it would be random, as the lamb will not first ask "is my mom dominant and has the others been born yet". :wink:

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 Post subject: Re: Antelope: Impala
Unread postPosted: Mon Jan 25, 2010 8:55 am 
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My question on this topic is...

Late last year the Impala in the south of the park had given birth already and in the north they were still carrying. After the first proper rains in the north the Impala all gave birth, this was more than a month later than their cousins in the south. Now did the ones in the north mate more than a month later than the ones in the south, did they know at that stage that the rains would be later in this area?

I still think that they will hold out a certain amount of time for the rains to come.


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 Post subject: Re: Antelope: Impala
Unread postPosted: Tue Jan 26, 2010 8:58 am 
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maybe this is also true for impalas???

http://en.wikipedia.org/wiki/Delayed_implantation

:hmz:


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 Post subject: Re: Antelope: Impala
Unread postPosted: Wed Jan 27, 2010 8:49 am 
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As far as I know (about roe deer, 'ree'), environmental regulators are induced by seasonal patterns. So the winter temperature and circumstances determine the time when the obligate diapause stops and the embryo starts to develop (5 months). I'm not aware of any mechanism that makes it possible for a roe deer to predict the seasonal circumstances in the comming summer. Maybe impala's can? :clap:

Does anyone know whether diapause is observed in impala's? Cant find any information or research on that.


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 Post subject: Re: Antelope: Impala
Unread postPosted: Wed Jan 27, 2010 5:38 pm 
Excellent info and points, Alko! :thumbs_up:

All this would make excellent theses for students/post-grads! :pray:




(I think some female forumites have exhibited diapause...don't know about Impalas... :whistle:)


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