Wednesday, June 13, 2007

Brock v. Bambi

Over the last six years or so, while the ISG have been trying to catch badgers, Defra have been looking at transmission opportunities for the infection of cattle with bTb by wildlife and have now published their results. It is also of note, that they have used several pieces of research, produced over a long time. It's good to see them joining up the dots.

They say:
"Feeding cattle at pasture may be particularly risky (Christiansen & Clifton-Hadley 2000), possibly since many modern cattle feeds are particularly palatable to badgers (Benham 1985; Garnett et al. 2002). Indeed, badgers utilised a feed trough at pasture in Gloucestershire so regularly that they established a latrine within it (Garnett et al. 2003). Feed in the trough may also have been exposed to contamination from urine and sputum whilst the badgers fed.

Deer have not been recorded feeding from troughs or feed placed on the ground for cattle in the UK."

We also learnt from PQ's that the biosecurity advice offered to farmers as to the height of cattle feeding troughs, to prevent badger access, was not a deal of use, as they had subsequently been filmed in troughs up to 4'3" off the ground. Which, as Defra quite rightly observed "is too high for cattle to use". And they didn't have to climb on each others shoulders to get in either; it was the lightest (most emaciated?) individuals who jumped up, hooked long front claws over the rim edge and then swung their backsides in. Job done.

Defra point out that problems in Michigan, USA with the white tailed deer, were made worse by the supplementary feeding of the deer, to encourage population growth for sport. All such supplementary feeding of deer with its associated cattle contact, is now banned.

The paper continues:

"Cattle may also come into contact with potentially infectious material when investigating badger setts at pasture or within woodlands to which they have access. Cattle routinely head-rub at badger setts and will investigate discarded bedding, which may pose a transmission risk (Phillips et al. 2003). In addition, badger latrines at setts often accumulate large amounts of faeces from several individuals, which may pose a significant transmission risk to cattle. Badgers may die above or below ground and may subsequently be excavated from the sett by other badgers. Investigation of infected carcasses by cattle may also pose a transmission
risk as it does with possums in New Zealand (Nugent 2005)."

On transmission risks within farm buildings (3.1.5) the paper describes:

"Cheeseman & Mallinson (1981) recorded that between 1972 and 1980, 64% of badgers found dead or in extremis in farm buildings in Gloucestershire and Avon were infected with M. bovis in comparison to 21% of badgers killed in RTAs in the same area. Also in Gloucestershire badgers regularly visited farmyards and buildings to utilise a diversity of resources, including many (such as cattle feed) that would subsequently be used by cattle (Garnett et al. 2002). More recently, badger visits to farm buildings have been estimated as a common and widespread phenomenon across the southwest of England (CSL 2006). During these visits badgers were observed making direct contact with cattle and excreting in buildings and farmyards. Thus badger visits to farm buildings may pose a significant risk of M. bovis transmission to cattle if direct contact is made between the two species or if badgers contaminate resources that cattle may subsequently consume (CSL 2006; Tolhurst 2006)."

With that we would agree. But keeping them out? Easy it is not.

In direct contrast to these badger visits to farm buildings, Defra point out that during 2112 hours of direct observation and 9360 camera hours of indirect surveillance of wildlife activity around 18 farms in southwest England (CSL 2006; Tolhurst 2006) and 1779 hours of direct observation of wildlife activity around 212 farms in Michigan, USA (Hill 2005) no deer of any species were observed entering farmyards, instead restricting their activity to woods and fields around the study farms.

And they conclude:
"Thus it is likely that both direct and indirect transmission risks posed by wild deer to cattle are likely to be very low to zero within farmyards and buildings.

The paper describes populations of several different species of deer all of which have 'spread their ranges' considerably over the last 30 years. (Ward 2005)

3.1.6 Distribution of deer and badgers
From the maps presented distribution throughout the southwest of England can be described. Roe deer are present within nearly every 10km square in the southwest, absent only from the Midlands in the north, the far west of Cornwall and a few
scattered squares throughout Devon and Somerset. Red deer are widely distributed throughout Cornwall and Devon, particularly the north but were largely absent elsewhere in the southwest. Large herds of red deer are known from Exmoor and the Quantock hills (Langbein 1997). As with their distribution throughout the rest of Britain, fallow deer are widely but patchily distributed in the southwest, being absent from large areas of northern Cornwall and Somerset. Japanese sika populations are rare in southwest England, being mainly focussed around the Purbeck hills and Poole basin, although there have been scattered observations mainly in Cornwall,
Devon and Dorset. Reeves’ muntjac are also patchily distributed in the southwest, with a better defined range in Gloucestershire and Wiltshire than more southerly counties, despite scattered reports from Devon and Cornwall. Chinese water deer (Hydropotes inermis) were largely absent from the southwest, the only known (small) breeding population existing in the Mendip hills. TB has not been recorded in Chinese water deer in the UK, so this species will not be considered further within this study."

and on badgers?
Wilson et al. (1997) recorded 143 badger setts within 205 10km squares in southwest England during the 1990s, an increase of 23% since the previous decade. In addition, estimated badger densities in this region were the highest in the whole of Britain. Hence, it can be concluded that badgers are widespread and abundant in the southwest.

Several contributers to this site have been offered 'deer management' in the last few years, with qualified gamekeepers holding a special licence responsible for controlling deer numbers over a wide area and encompassing many farms.

See more of this paper on the Defra website

1 comment:

Anonymous said...

Badger cull abandoned after TB report

By Charles Clover, Environment Editor


Ministers are expected to abandon plans to license a widespread cull of
badgers after a decade-long study by independent scientists concluded
that a cull would only increase the spread of bovine tuberculosis.

The findings of the independent scientists, to be published on Monday,
were branded "unacceptable" last night by farmers who wanted Tony Blair
and David Miliband, the Environment Secretary, to lift the 10-year-old
ban on badger culling to help stop the spread of the disease.

The final report of the Independent Scientific Group, described by its
chairman, Prof Sir John Bourne, as the "comprehensive picture" of TB in
cattle and badgers, rules out badger culling on any scale as a way of
controlling the outbreaks.

The scientists' report says that while badgers are "clearly a source" of
TB in cattle, badger culling can make "no meaningful contribution" to
the control of the disease in Britain.

This is because badger culling trials, conducted over the past ten
years, have shown that badgers disturbed by a cull would move around
spreading the disease to both cattle and other badgers.

There were 1551 outbreaks of the disease in Britain last year -
affecting about 5 per cent of all herds - and 7000 herds were under
movement restrictions.

The disease cost £80 million last year in compensation to farmers and it
is estimated that because outbreaks are likely to increase it will cost
£2 billion by the end of the decade.

The report, results of which have been seen by The Daily Telegraph, says
culling around outbreaks of the disease in cattle would be "likely to
make matters worse rather than better."

The overall benefits of pro-active culling were modest, with an
estimated reduction of 14 outbreaks in an area of 1000 square kilometres.

Where culling was carried out, the beneficial effect on outbreaks in
cattle was offset by an increased incidence in surrounding un-culled areas.

The second key finding of the report, which has been submitted to Mr
Miliband, is that weaknesses in the present regime of cattle testing
means that cattle themselves contribute significantly to the spread of
the disease - because the full number of cattle with TB is not picked up.

In some parts of Britain, it says, cattle movements are likely to be the
main source of infection.

The scientists' findings lead them to conclude that the rising incidence
of bovine TB and its spread can be contained "by the rigid application
of cattle-based control measures alone."

Ministers are expected simply to welcome the report and say they will
consider a response in due course but a well-placed source close to the
Department for the Environment, Food and Rural Affairs said the
"definitively anti-culling" conclusions of the report meant a cull was off.

Mr Miliband is known to believe that any decision to cull must be backed
by the science or it would be open to judicial review.

The scientists' report does considers the case of Ireland where badger
culling has been going on for 20 years. It says the incidence of TB in
cattle in Ireland, despite badger culling, is twice what it is in Britain.

Ireland, which stopped pre-movement testing of cattle in 1996, found
that the number of cattle with the disease rose from 27,000 in 1996 to
45,000 in 1999, despite badger culling going on throughout that period.

Sir John says that there needs to be a far more rigorous approach to
pre-movement testing of cattle and the use of gamma interferon tests
which detect the disease earlier - though they are also known to give
false positives.

Sir John's report was expected to leave a chink of light for those who
believe that the eradication of the disease requires both pre-and
post-movement testing of cattle and the control of badgers. It does not.

Instead, it creates a huge quandary for the Treasury, for more rigorous
pre-movement testing of cattle would not only be more expensive, but
would be likely to find far more cases of bovine TB, pushing up the
compensation bill.

It would also be disastrous for farmers because they would lose income
from the presently undetected cattle.

Trevor Lawson of the Badger Trust said: "The new science will give
ministers the sound basis they need to formulate policy and get TB under
control - without a badger cull.

"The political challenge is to get farmers and vets together so they buy
into the science."

Anthony Gibson of the National Farmers' Union said: "The saving grace is
that Sir John concludes that badgers contribute significantly to the
disease in cattle. That being the case we just don't accept that it is
impossible to do something about that.

"It cannot be beyond the wit of man. His report is a counsel of despair.
We are not prepared to accept it as it stands."