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#16
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wood pidgeon life span
"Sue" wrote in message reenews.net... That's the general feeling round here in Norfolk. A couple of decades back the farmers would have regular organised county-wide woodpigeon shooting days. That doesn't seem to happen now, and we do have many more pigeons around. You sometimes see vast flocks of them feeding in fields, and there are definitely more making a nuisance of themselves in our garden than there used to be when we moved here in 1980. By 'nuisance' do you mean that they're eating your vegetables? That's the only sort of nuisance I can think of. I net my (admittedly small) vegetable plots to prevent that. Mary -- Sue |
#17
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wood pidgeon life span
"BAC" wrote in message ... "Nick Maclaren" wrote in message ... In article , Malcolm writes: | | If the birds weren't shot, the mortality would go down and their | life-expectancy up. That is extremely unclear, and might be the converse of the truth. It will depend very much on how close they are to overpopulation at the stressful times of year. It is quite possible that stopping shooting them would cause an increase in their population, and a consequent increase in their mortality rate and a reduction in their life expectancy. That is what often happens to prey species with effectively no predation - as is the case for wood pigeons in many parts of the UK. Are you saying that, for a given ecosystem, only a certain maximum number of a population of birds can be expected to survive the winter, regardless of how many more than that number started the winter? All other things being equal any given ecosysyem can only produce a limited amount of food which can only support a limited number of birds. Given the rate at which birds such as wood pidgeons can reproduce its fairy clear that all other things being equal they will exhaust the food resources of any given ecosystem within a few generations. With surplus birds either moving elsewhere - which doesn't really soleve anything, or simply dying from starvation. Thus maintaining an equilibrium. The same probably applies to song birds as well. The large numbers which are allegedly killed by domestic cats each year, quite possibly free up food supplies over winter for others which would otherwise have perished. It's simply that birds killed by cats are probably more noticeable than those which starve in out of the way places and rot down to nothing within weeks. michael adams .... |
#18
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wood pidgeon life span
"Malcolm" wrote in message ... In article , Nick Maclaren writes In article , Malcolm writes: | | If the birds weren't shot, the mortality would go down and their | life-expectancy up. That is extremely unclear, and might be the converse of the truth. It will depend very much on how close they are to overpopulation at the stressful times of year. It is quite possible that stopping shooting them would cause an increase in their population, and a consequent increase in their mortality rate and a reduction in their life expectancy. That is what often happens to prey species with effectively no predation - as is the case for wood pigeons in many parts of the UK. I'm impressed that you appear to think you know more about woodpigeons than Ron Murton, who devoted several years to their study and wrote a very well-received monograph on the species. I stand by what I said, which is based on his studies. -- Malcolm He (Nick) is into statistics so his view has a probability of being correct:-) |
#19
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wood pidgeon life span
"Reginald" wrote in message ... Not long in my garden. How do you manage to achieve that? Alan |
#20
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wood pidgeon life span
"Malcolm" wrote in message ... In article ews.net, Sue writes "Nick Maclaren" wrote Malcolm writes: | | If the birds weren't shot, the mortality would go down and their | life-expectancy up. That is extremely unclear, and might be the converse of the truth. It will depend very much on how close they are to overpopulation at the stressful times of year. It is quite possible that stopping shooting them would cause an increase in their population, and a consequent increase in their mortality rate and a reduction in their life expectancy. That is what often happens to prey species with effectively no predation - as is the case for wood pigeons in many parts of the UK. That's the general feeling round here in Norfolk. A couple of decades back the farmers would have regular organised county-wide woodpigeon shooting days. That doesn't seem to happen now, and we do have many more pigeons around. You sometimes see vast flocks of them feeding in fields, and there are definitely more making a nuisance of themselves in our garden than there used to be when we moved here in 1980. But that doesn't seem to agree with Nick's suggestion that an increase in population would lead to an increase in mortality and a reduction in life expectancy which would bring the population back down again. No, it doesn't, but I don't think Nick is the only person to think what he thinks about the subject. I have seen it suggested elsewhere that the farming community came to believe that the traditional autumn culls of wood pigeons actually increased the numbers surviving the winter to breed the following spring. If so, that might explain Sacha's observation that the wood pigeon shoots have been reduced, although not, as you say, her subsequent observation this has led to an increase in the wood pigeon population :-) What's wrong with woodpigeons in gardens, anyway? |
#21
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wood pidgeon life span
In article , Janet Baraclough writes: | | There are circumstances under which that is the case. It is true for | red deer in many parts of the Highlands. | | Um, if that were true for red deer in the Highlands, surely their | population would be static? AIUI, their population has multiplied in | recent decades, putting far more pressure on local ecology. No, that is overly simplistic. In the real world, things are rarely black and white, and they almost never are in ecology. For example, the weather varies from year to year. In many or most parts of the Highlands, the principle factor restricting red deer numbers is winter starvation, which is why culling is humane and banning it is not. In some cases, the numbers have increased because the culling has been cut back to increase the population, but there is also the fact that the winters have been getting milder for the past few decades. But, overall, the fact that there are more deer does not conflict with their average lifespan being shorter. Provided that enough manage to breed, the figures are largely independent. Regards, Nick Maclaren. |
#22
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wood pidgeon life span
In article , "BAC" writes: | "Malcolm" wrote in message | ... | | But that doesn't seem to agree with Nick's suggestion that an increase | in population would lead to an increase in mortality and a reduction in | life expectancy which would bring the population back down again. | | No, it doesn't, but I don't think Nick is the only person to think what he | thinks about the subject. Ogilvie has misquoted again, too. Me, certainly, and probably Murton. I never said or implied that a reduction in their life expectancy would result in a reduction in their population. Assuming that the latter follows automatically from the former shows a severe misunderstanding of population dynamics. Few ecologists will make that mistake. | I have seen it suggested elsewhere that the | farming community came to believe that the traditional autumn culls of wood | pigeons actually increased the numbers surviving the winter to breed the | following spring. If so, that might explain Sacha's observation that the | wood pigeon shoots have been reduced, although not, as you say, her | subsequent observation this has led to an increase in the wood pigeon | population :-) It is a known phenomenon, and has been observed in many species, which is why I said that it might well occur in this case. It is quite possible that the increase has been due, primarily at least, to the mild winters and the culling has a very secondary effect. | What's wrong with woodpigeons in gardens, anyway? In moderation, nothing. The problem is that they don't have appropriate predation pressure in the UK. Regards, Nick Maclaren. |
#23
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wood pidgeon life span
"Nick Maclaren" wrote in message ... | What's wrong with woodpigeons in gardens, anyway? In moderation, nothing. The problem is that they don't have appropriate predation pressure in the UK. Except by man. I eat a lot of wood pigeon :-) Mary |
#24
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wood pidgeon life span
In article , "Mary Fisher" writes: | | | What's wrong with woodpigeons in gardens, anyway? | | In moderation, nothing. The problem is that they don't have appropriate | predation pressure in the UK. | | Except by man. I eat a lot of wood pigeon :-) With the suburbanisation of the south-east and midlands, there isn't enough of that to be called "appropriate predation pressure" any longer. This is precisely why we have a deer crisis, after centuries of deer being almost endangered in the lowlands of the UK, with no reduction whatsoever in their 'natural' predators (there being none). Regards, Nick Maclaren, University of Cambridge Computing Service, New Museums Site, Pembroke Street, Cambridge CB2 3QH, England. Email: Tel.: +44 1223 334761 Fax: +44 1223 334679 |
#26
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wood pidgeon life span
"Nick Maclaren" wrote in message ... In article , "Mary Fisher" writes: | | | What's wrong with woodpigeons in gardens, anyway? | | In moderation, nothing. The problem is that they don't have appropriate | predation pressure in the UK. | | Except by man. I eat a lot of wood pigeon :-) With the suburbanisation of the south-east and midlands, there isn't enough of that to be called "appropriate predation pressure" any longer. This is precisely why we have a deer crisis, after centuries of deer being almost endangered in the lowlands of the UK, with no reduction whatsoever in their 'natural' predators (there being none). Yes, I understand that. Yet here in the north wood pigeons, deer and hare are all regarded as vermin in many places and are killed. We're lucky to have them freely available for the table. In the northern suburbs wood pigeons aren't enough of a pest to be a problem for most of us. Nevertheless, when Spouse gets his air rifle ... Mary |
#27
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wood pidgeon life span
"Malcolm" wrote in message ... In article , "Rupert (W.Yorkshire)" writes "Malcolm" wrote in message ... In article , Nick Maclaren writes In article , Malcolm writes: | | If the birds weren't shot, the mortality would go down and their | life-expectancy up. That is extremely unclear, and might be the converse of the truth. It will depend very much on how close they are to overpopulation at the stressful times of year. It is quite possible that stopping shooting them would cause an increase in their population, and a consequent increase in their mortality rate and a reduction in their life expectancy. That is what often happens to prey species with effectively no predation - as is the case for wood pigeons in many parts of the UK. I'm impressed that you appear to think you know more about woodpigeons than Ron Murton, who devoted several years to their study and wrote a very well-received monograph on the species. I stand by what I said, which is based on his studies. -- Malcolm He (Nick) is into statistics so his view has a probability of being correct:-) I, too, have some statistical knowledge:-) -- Malcolm 0 1 |
#28
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wood pidgeon life span
"Nick Maclaren" wrote in message ... In article , "BAC" writes: | "Malcolm" wrote in message | ... | | But that doesn't seem to agree with Nick's suggestion that an increase | in population would lead to an increase in mortality and a reduction in | life expectancy which would bring the population back down again. | | No, it doesn't, but I don't think Nick is the only person to think what he | thinks about the subject. Ogilvie has misquoted again, too. Me, certainly, and probably Murton. You mean Dr O appears to have misunderstood what you wrote? I never said or implied that a reduction in their life expectancy would result in a reduction in their population. Assuming that the latter follows automatically from the former shows a severe misunderstanding of population dynamics. Few ecologists will make that mistake. Not without precisely defining all the other variables, certainly. | What's wrong with woodpigeons in gardens, anyway? In moderation, nothing. The problem is that they don't have appropriate predation pressure in the UK. Not enough grey squirrels in those wood pigeon's woods, then :-) |
#29
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wood pidgeon life span
In article , "BAC" writes: | | | But that doesn't seem to agree with Nick's suggestion that an | | increase in population would lead to an increase in mortality | | and a reduction in life expectancy which would bring the | | population back down again. | | Ogilvie has misquoted again, too. Me, certainly, and probably Murton. | | You mean Dr O appears to have misunderstood what you wrote? I would assume that for most people, but his record is such as to make that the less likely scenario. I have included the quote, in full, and you should note the absence of any separation between what I said and what I didn't say. | I never said or implied that a reduction in their life expectancy would | result in a reduction in their population. Assuming that the latter | follows automatically from the former shows a severe misunderstanding | of population dynamics. Few ecologists will make that mistake. | | Not without precisely defining all the other variables, certainly. Which is why I doubt that Murton said it. I got caught before by Dr O misquoting Stace, and maligned Stace by assuming that Dr O's quote was correct. I am trying to avoid falling into that trap again. In any case, it is notoriously difficult to estimate the effect of changes in life expectancy in nature, as improved conditions can equally well increase that or increase the breeding rate (with a possible reduction in life expectancy). Almost all ecologists know that! | Not enough grey squirrels in those wood pigeon's woods, then :-) Well, maybe :-) As appropriate predators for wood pigeons, I wouldn't rate grey squirrels very highly; they aren't exactly specific! One of the reasons that I made that remark is that I have read (informed) speculations that the rise in the numbers of wood pigeons and collared doves may be a factor in the near-demise of sparrows. There is certainly a fair correlation, and a realistic causal chain. And, if so, grey squirrels clearly aren't any use at controlling pigeons, as they are at population limits in the most sparrowless areas. Regards, Nick Maclaren. |
#30
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wood pidgeon life span
"Nick Maclaren" wrote in message ... In article , "BAC" writes: | | | But that doesn't seem to agree with Nick's suggestion that an | | increase in population would lead to an increase in mortality | | and a reduction in life expectancy which would bring the | | population back down again. | | Ogilvie has misquoted again, too. Me, certainly, and probably Murton. | | You mean Dr O appears to have misunderstood what you wrote? I would assume that for most people, but his record is such as to make that the less likely scenario. I have included the quote, in full, and you should note the absence of any separation between what I said and what I didn't say. | I never said or implied that a reduction in their life expectancy would | result in a reduction in their population. Assuming that the latter | follows automatically from the former shows a severe misunderstanding | of population dynamics. Few ecologists will make that mistake. | | Not without precisely defining all the other variables, certainly. Which is why I doubt that Murton said it. I got caught before by Dr O misquoting Stace, and maligned Stace by assuming that Dr O's quote was correct. I am trying to avoid falling into that trap again. I have not read Murton on wood pigeons, and cannot comment on what he wrote on the subject, and i think I'd better stop there because I've no wish to become embroiled in a 'who said what' dispute between Malcolm and yourself. In any case, it is notoriously difficult to estimate the effect of changes in life expectancy in nature, as improved conditions can equally well increase that or increase the breeding rate (with a possible reduction in life expectancy). Almost all ecologists know that! | Not enough grey squirrels in those wood pigeon's woods, then :-) Well, maybe :-) As appropriate predators for wood pigeons, I wouldn't rate grey squirrels very highly; they aren't exactly specific! One of the reasons that I made that remark is that I have read (informed) speculations that the rise in the numbers of wood pigeons and collared doves may be a factor in the near-demise of sparrows. There is certainly a fair correlation, and a realistic causal chain. And, if so, grey squirrels clearly aren't any use at controlling pigeons, as they are at population limits in the most sparrowless areas. The grey squirrel reference was a joke, of course. The increase in collared dove population is an interesting point, because they are relative newcomers, and there does seem to be a correlation between their establishment here and the sparrow decline, although that may merely be coincidence. What is the 'realistic causal chain' you have in mind, though? |
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