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Badgers v hedgehogs - opportunism or direct population limitation? (1 Viewer)

Nightranger

Nightranger

Senior Moment
In a current thread Alf posited the idea of badgers being a limiting factor on the population of hedgehogs. All older research suggests this is density-dependent despite the apparent appearance of selective predation on certain species in certain habitats in more recent research. Is selective predation more widespred than we have been led to believe? If so, this would strengthen the idea of culling badgers currently in vogue by many rural MPs by giving a conservation twist to the subject.

However, on examining the following papers:

http://www.sekj.org/PDF/anzf32/anz32-037-045.pdf (This covers a different aim of research but references earlier work about the badger diet comprising earthworms).

http://www.badger.org.uk/_Attachments/Resources/283_S4.pdf (this is a general work that sets out the fact that the European badger (Meles meles) is an omnivore and an opportunistic feeder).

digital.csic.es/bitstream/10261/43502/1/martin_oecologia_95.doc (This paper sets out the point that European badgers forage along density-dependence rules)

http://www.academia.edu/671427/The_Ecology_of_the_European_badger_Meles_meles_in_Ireland_-_a_review (this is an Irish study for comparison and there is a useful table at p.122)

http://www.researchgate.net/publica..._comparison_and_critique_of_different_methods (you may have to click on options to get the paper up but again, a useful graphic at p.26)

This will do for now but a note for Alf - the American mink v water vole situation is different, you know it, I know it and everyone else knows it. Care for a proper discussion instead of a shin-kicking exercise? ;)
 
http://www.southampton.ac.uk/~cpd/wardetal.pdf (I may have been wrong about co-feeding [where this has been observed, may have been under unusual circumstances], this paper sets out that hedgehogs have a defensive response to the presence of badgers. However, I have yet to find any other papers than those quoted by Alf to say that badgers specifically target hedgehogs against the presence of other prey).
 
http://www.dailymail.co.uk/news/art...gers-developed-taste-spiky-little-rivals.html

http://www.independent.co.uk/enviro...hogs-coincidence-i-dont-think-so-6291446.html

http://www.telegraph.co.uk/earth/wi...-decline-because-badgers-are-eating-them.html (there is a pattern in these links and I hope it is not one that Alf is choosing to favour. As I pointed out, this subject has a serious edge but I have to be honest in posting these as they appear if you take on particular Google searches)

http://thehedgehog.co.uk/dangers.htm ( quote - Badgers
Avoid releasing hedgehogs anywhere near a badger's sett. Badgers have always been the hedgehogs primary natural predator and eat hedgehogs. Foxes also bite, injure and kill hedgehogs. Baby hedgehogs are vulnerable to attack from stoats, weasels and rats.)

http://www.independent.co.uk/enviro...badgers-for-killing-off-hedgehogs-448455.html (oh dear!)
 
Unless one wishes to suggest that either Badgers or Hedgehogs are introduced animals (hush a minute you on the Uists) the two species have co-habited these islands since time immemorial without one wiping out the other. It is therefore pointless to blame a sudden decrease in hedgehogs on anything other than the destabilising ecological effect of human over-population and industrialisation.

Hedgehogs require substantial cover including refuges for hibernation in their territories and modern farmland generally is designed to remove these in favour of crop production areas. The result is bound to be unfavourable for hedgehogs either by limiting their ability to house themsselves unpredictably or away from badger setts/highways, or by limiting their foraging areas compared to areas where they are vulnerable and obvious.

John
 
Farnboro John said:
Unless one wishes to suggest that either Badgers or Hedgehogs are introduced animals (hush a minute you on the Uists) the two species have co-habited these islands since time immemorial without one wiping out the other. It is therefore pointless to blame a sudden decrease in hedgehogs on anything other than the destabilising ecological effect of human over-population and industrialisation.

Hedgehogs require substantial cover including refuges for hibernation in their territories and modern farmland generally is designed to remove these in favour of crop production areas. The result is bound to be unfavourable for hedgehogs either by limiting their ability to house themsselves unpredictably or away from badger setts/highways, or by limiting their foraging areas compared to areas where they are vulnerable and obvious.

John
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Indeed John and thanks. Alf thinks badgers are the absolute controlling factor
on hedgehogs wherever the two co-exist. His proof is based on studies on arable farmland, which are pretty artificial to start with but are also, habitats where preferred food is reduced by land management strategies (use of pesticides, reduction of hedgerows [badger setts and hedgehog refuges] and miscellaneous pest management strategies aimed at foxes, rats and mice but with collateral victims).
 
Nightranger wrote:
In a current thread Alf posited the idea of badgers being a limiting factor on the population of hedgehogs.

Thank you for those links, I was particularly struck by the following:

http://www.academia.edu/671427/The_E...and_-_a_review:

‘Badger populations impact on the abundance of other mammal species through competitive release or predation. Culling badgers for disease control was associated with increases in red fox, Vulpes vulpes, densities of 1.6Á 2.3 foxes km(2during a randomized badger culling trial in Britain(Trewbyet al.2008). Young et al.(2006) found that as sett density increased in suburban areas, both the probability of occurrence of hedgehogs and their abundance decreased. Furthermore, a generalized linear model predicted that the probability of hedgehog occurrence in suburban habitats declined towards zero in areas of high badger density. In Ireland, O’Shea et al. (2010) reported that there were significantly more road-killed hedgehogs in the Cork removal area of the Four Area Project than in the reference area.

‘Furthermore, a generalized linear model predicted that the probability of hedgehog occurrence in suburban habitats declined towards zero in areas of high badger density’.

Alf I am afraid was wrong in ‘positing the idea of badgers being a limiting factor on the population of hedgehogs’ he should have posited the idea that they are an exterminating factor.
 
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Did the Irish research take account of the fact that Cork is the only place in the Irish Republic with a dual carriageway? Perhaps that accounted for the increase in hedgehog roadkill.

John
 
Farnboro John said:
Did the Irish research take account of the fact that Cork is the only place in the Irish Republic with a dual carriageway? Perhaps that accounted for the increase in hedgehog roadkill. John
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It wouldn't be PC to make any Irish jokes at this point, and so instead I'll relate a true story of when I was roaming about central Turkey. Now the hospitality and kindness I encountered almost unversally in small towns and villages were humbling.

However, where someone had served as a mayor (or its equivalent) of a small town for some time, it was not uncommon to find a short stretch of dual carriageway on the edge of town, built (I presumed) as celebrating the mayor's achievement. The only drawback was that both carriageways were used for two-way traffic, but in both directions in each lane...

At the end of the dual carriageway, the overhead banner always read "Güle, Güle" ('Bye-bye'), and if I hadn't collected any wrong-way cyclists on the front of the vehicle, I always waved, and received cheerful waves in return.

It was wonderful material for observational humour!
MJB
 
Farnboro John said:
Unless one wishes to suggest that either Badgers or Hedgehogs are introduced animals (hush a minute you on the Uists) the two species have co-habited these islands since time immemorial without one wiping out the other. It is therefore pointless to blame a sudden decrease in hedgehogs on anything other than the destabilising ecological effect of human over-population and industrialisation.

John
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Time immemorial for our ecosystem started 12000 years ago with the end of the ice age, and the badger will have been predated, principally by man, for the vast majority of that time. Badgers, hedgehogs and man have lived in equilibrium sufficient for all three species to have survived to 1992 when we abandoned our responsibility as a predator, and the badger was protected. Since then the Badger population has exploded.

Darwin wrote the following in ‘The Origin of Species’

The amount of food for each species of course gives the extreme limit to which each can increase; but very frequently it is not the obtaining food, but the serving as prey to other animals, which determines the average numbers of a species.

The Badger, like man is an omnivorous predator, and its population is not affected by the extinction of individual components of its diet. The hedgehog is likely to be only the tip of the iceberg.

It seems to me that it is lunatic for wildlife charities to (rightly) complain of degradation of habitat, while at the same time protecting the most versatile predator (bar ourselves) in our ecosystem!
 
Dry ice said:
Time immemorial for our ecosystem started 12000 years ago with the end of the ice age, and the badger will have been predated, principally by man, for the vast majority of that time. Badgers, hedgehogs and man have lived in equilibrium sufficient for all three species to have survived to 1992 when we abandoned our responsibility as a predator, and the badger was protected. Since then the Badger population has exploded.

It seems to me that it is lunatic for wildlife charities to (rightly) complain of degradation of habitat, while at the same time protecting the most versatile predator (bar ourselves) in our ecosystem!
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According to gamekeepers records hedgehogs have been in steady decline since the 1960s, a time when badgers were still heavily persecuted.

Badgers have increased since well before 1992 infact, the first Badger Act was introduced in 73. However we have by no means "abandoned our reponsibility" as you put it, our desire for badger blood by digging, dogs, guns, poison and snares has just in part been replaced indirectly by cars. Road deaths currently account for about a sixth of the UK population each year and deaths by illegal persecution aren't insignificant. To say there has been a population explosion since 1992 is, I think, misleading...

Where habitat isn't ideal badgers are known to impact the hedgehog population. It's stated as fact in current badger literature. But to suggest (as others have) that badgers are the direct cause of decline is ridiculous, there are countless other significant factors to take into account. Hedgehog population information is also frustratingly weak.

Would you rather the laws were repealed and we went back to the good old days of (legal) badger baiting and snaring?
 
turkish van said:
Where habitat isn't ideal badgers are known to impact the hedgehog population. It's stated as fact in current badger literature. But to suggest (as others have) that badgers are the direct cause of decline is ridiculous, there are countless other significant factors to take into account. Hedgehog population information is also frustratingly weak.
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Thanks for this summing up, it is pretty much what I was thinking about when I started this thread. As far as I am aware, this information has come from various hedgehog relocation studies, including Hugh Warwick's although I don't know of any Internet references.
 
Nightranger said:
Thanks for this summing up, it is pretty much what I was thinking about when I started this thread. As far as I am aware, this information has come from various hedgehog relocation studies, including Hugh Warwick's although I don't know of any Internet references.
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I think you're right, also Patrick Doncaster - there is one of his original studies from 1992 here but you need to register to read the whole paper
 
I know you are right, and environmental factors have caused declines in hedgehog numbers in parts of Britain, however:

‘Young et al. (2006) found that as sett density increased in suburban areas, both the probability of occurrence of hedgehogs and their abundance decreased. Furthermore, a generalized linear model predicted that the probability of hedgehog occurrence in suburban habitats declined towards zero in areas of high badger density’.---This is extermination.

It matters not a jot how good or bad habitat is for hedgehogs, once badger population, in that habitat, reaches a critical mass, then the hedgehog’s days are numbered.


turkish van said:
I think you're right, also Patrick Doncaster - there is one of his original studies from 1992 here but you need to register to read the whole paper
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Thank you for this; I note that 3 of 12 introduced hedgehogs were eaten by badgers in an area of relatively low badger density (5/sq km) in a two month period (you do the sums), and of 30 hedgehogs introduced to the area of high badger density (20/sq km), 7 were eaten, and most of the rest managed to find safety in badger free habitat.

But that was 20 years ago; since then badger populations have increased many times over and predation of hedgehogs (if they can find any) will have increased correspondingly. Furthermore there is far less badger-free habitat in which hedgehogs can find refuge.

It is little wonder that in two recent surveys http://www.guardian.co.uk/environmen...amatic-decline
The first ‘showed a decline of sightings by 32% from 2001 to 2011, and the latter a decrease of 37% from 2003 to 2012’
 
The answer to all of this is reintroduction of the wolf across the whole of Britain. That will curtail Badger activity, decrease feral and loose pet cat predation of wildlife and going on recent Canadian experience deal with stray dogs as well.

The fact that it will also result in a requirement for human livestock guards 24/7 will enhance employment prospects in the security industry. It will particularly benefit the practically unemployable beetle-browed unskilled part of the workforce so it is essentially care in the community.

John
 
turkish van said:
Where habitat isn't ideal badgers are known to impact the hedgehog population. It's stated as fact in current badger literature. But to suggest (as others have) that badgers are the direct cause of decline is ridiculous, there are countless other significant factors to take into account. Hedgehog population information is also frustratingly weak.

Iam not sure what 'current badger literature' you are reading.

To quote Tim Roper's definitive Book ,The Badger' (2010) 'Badgers are significant predators of both adult and young western hedgehogs' and 'survey work on both local and regional scales, has revealed consistent negative correlations between hedgehog numbers and badger numbers, suggesting that the absence of hedgehogs from rural areas in most of western and central England is a consequence of predation by badgers'.
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Ernest Neal, in his classic book ‘The Badger’ (published 1948), records autopsies of 9 badgers: 6 from Somerset; 2 from Gloucestershire; and 1 from Oxford, amongst the stomach contents of the latter were ‘Four hedgehogs. All appeared to be adults. Only three spines swallowed’. The reciprocal relationship between badgers and hedgehogs is borne out by the fact that his distribution map indicates even then, that badgers were abundant in Somerset and Gloucester, whereas in Oxford, they were ‘relatively rare’.

In the text he remarks that ‘Hedgehogs are certainly a favourite food’ and ‘it is not at all unusual to find the skin of a hedgehog with the meat removed left flattened on its back. This is certainly the work of a Badger’.

I have lived in the area of the proposed west Somerset badger cull (where Neill did most of his work) for all of my sixty years. Before the badger was protected, hedgehogs and badgers were regularly seen. Now you never see a hedgehog dead or alive, but badgers are ubiquitous. In his book he describes this area as being abundant for badgers. It is now over-run with them!
 
Dry ice said:
I have lived in the area of the proposed west Somerset badger cull (where Neill did most of his work) for all of my sixty years. Before the badger was protected, hedgehogs and badgers were regularly seen. Now you never see a hedgehog dead or alive, but badgers are ubiquitous. In his book he describes this area as being abundant for badgers. It is now over-run with them!
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With respect Dry ice, I did not set this thread up for it to become an anti-badger platform and I am well aware of common lore with regard to badger predation on hedgehogs. What I asked was something more specific and untested observational experience does not help. For example, I live in north Greater Manchester (east Lancashire) and although hedgehogs are seen, they are far from common and the population appears to be falling. I am sure you would be delighted if you read that badgers are common here at this point but the reverse is true and I could not tell you where the nearest sett is. Our fox population appears to be growing but I am sure it is mostly overspill from urban places like Salford and the two things are coincidence. Having said that, rabbits are making a slow come back but not enough to explain what is feeding the foxes. I am not making a case against foxes BTW but merely demonstrating that untested observations do not work.
 
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