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life expectancy?: |
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green_toad Member Joined: 22 Sep 2003 No. of posts: 12  View other posts by green_toad |
Posted: 28 Jul 2005 Just out of interest does anyone know the average life expectancy for the common lizard? I've tried searching for this info without any success. |
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rhysrkid Senior Member Joined: 14 Nov 2003 No. of posts: 98  View other posts by rhysrkid |
Posted: 29 Jul 2005 Hi Rhys |
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green_toad Member Joined: 22 Sep 2003 No. of posts: 12 View other posts by green_toad |
Posted: 29 Jul 2005 many thanks for that info. I expect all the cats around my area reduce their life expectancy quite considerable. Admittedly it's usually slow worms I have to rescue from the neighbours cats. |
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green_toad Member Joined: 22 Sep 2003 No. of posts: 12 View other posts by green_toad |
Posted: 29 Jul 2005 [QUOTE=rhysrkid] The average life expectancy for a West Country population was around 4-5 years [/QUOTE] I take it that's a mean average? As females don't mature until 3 years, I would of thought that the population wouldn't be viable if very few lived beyond 4 or 5.
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rhysrkid Senior Member Joined: 14 Nov 2003 No. of posts: 98 View other posts by rhysrkid |
Posted: 30 Jul 2005 The life expectancy was actually 4-5 years after the first
season (sorry) so the average age would have been 5-6 years old. Clearly,
being an average, some individuals will live longer while others fall short. I
would say, even if many did only reach 4-5 years old, provided they have
breeding success in those years following maturation, the population could be
self-sustaining. Although females take
longer to mature than males, they also tend to live longer. Rhys |
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rhysrkid Senior Member Joined: 14 Nov 2003 No. of posts: 98 View other posts by rhysrkid |
Posted: 30 Jul 2005 Its an interesting point that you have made... B&G state that 90% of viv lizards are thought to die in their first year but if they survive this they average a further 4-5 years (in the west country popn). As you say, females take around 3 years to mature - you would think that there would be selective pressure to mature earlier and therefore increase your reproductive fitness by having more seasons in which you can breed. Apprently, 50% of viv lizards in France reach maturity after just a single year so they are obviously capable - perhaps it is the cooler climate here that restricts this more rapid development? I guess for our lizards, several reproductive years is sufficient. Rhys |
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Mick Member Joined: 10 Jun 2005 No. of posts: 184  View other posts by Mick |
Posted: 25 Aug 2005 Well fed in captivity & safe from predation Vivip's - as with many captive herptile species - can live to a very ripe old age. One of the females i caught back in the early 1990's for my outdoor Vivip' terrarium survived for as long as i kept Vivip's, which was about 8, or 9y'rs. She was already matured enough to breed when i caught her & only didn't come out of hibernation in the final year i maintained the now overgrown terrarium. Most juveniles were annually released & i eventually just let any adults die out naturally, which tended to occur in hibernation. Anyway, that particular female must've been at least 10, or 11y'rs old & i'm sure i recall she gave birth every single year. Think she was even one of those which died with their original tails intact, unlike half the 10 i began my colony with which already had regenerated, imperfect tails. |
- life expectancy? |