In late 2013, more than 1,000 badgers were culled in two pilot zones - Somerset and Gloucestershire - in an attempt to control TB in cattle.
The government says the action is needed to help tackle bovine TB, a disease of cattle that can be spread by badgers.
Campaigners against the cull say the policy will have no impact on bovine TB, and could lead to local populations of badgers being wiped out.
Q: What took place?
A: The trials took place in areas where there were a high number of TB infections in cattle to assess whether badgers could be culled humanely, safely and effectively.
The precise areas where badgers were shot by trained marksmen was not revealed.
One area was in West Somerset and the other in and around West Gloucestershire.
A third area, in Dorset, was prepared in reserve but there was no culling last year.
The cull aimed to kill at least 70% of badgers across areas about the size of the Isle of Wight in each zone.
Q: How will the success of the pilot culls be measured?
A: The pilots do not look at scientific data. The Department for Environment, Food and Rural Affairs (Defra) will review:
- How humane the cull is. A government agency carried out sample post mortems to see if the badgers had been shot humanely. The carcasses were not tested for signs of TB infection.
- How effective (in terms of badger removal) the two badger pilots were. Initial estimates to kill around 5,000 badgers in the two areas were revised down to just over 2,500 in October after new data on badger numbers suggested the population had fallen over the winter. The government announced it was extending the six-week pilots by three weeks, after marksmen failed to reach the target of killing 70% of the badger population.
- How safe the two badger culling pilots were.
On the basis of the report by an independent panel - expected in March - ministers will make a decision about whether or not to extend the pilots to other areas of England.
Q: What is the scientific evidence for and against a cull?
A: Scientific evidence suggests sustained culls of badgers under controlled conditions could reduce TB in local cattle by 12-16% after four years of annual culls, and five years of follow-up, although it could be lower and it could be higher.
The randomised badger culling trial in England found that killing badgers disrupted their social groups, with surviving animals moving out to establish new groups, taking TB with them.
This perturbation effect led to an increase in cases of bovine TB outside of the cull zone, although the impact diminished over time.
The pilot culls attempted to use borders such as rivers and motorways to reduce the risk of badgers spreading TB to neighbouring areas, but this approach has not been fully tested.
The randomised badger culling trial trapped badgers in cages for the cull, while the main method planned for Gloucestershire and Somerset was free shooting, although cage trapping and shooting was also used.
Any deviation from methods used in the original trial will decrease or increase the expected impact on bovine TB, according to scientists.
Q: What is cattle TB?
A: Bovine tuberculosis (TB) is an infectious disease of cattle. It presents a serious problem for the cattle industry, causing financial and personal hardship for farmers.
The disease is caused by the bacterium Mycobacterium bovis (M. bovis), which can also infect and cause TB in badgers, deer and other mammals.
Cattle are regularly tested for TB and destroyed if they test positive.
Q: Why are badgers implicated in spreading TB?
A: Scientific evidence has shown that bovine TB can be transmitted from cattle to cattle; from badgers to cattle and cattle to badgers; and from badger to badger.
Badgers are thought to pass on the disease to cattle through their urine, faeces or through droplet infection, in the farmyard or in cattle pastures.
However, it is not clear how big a role badgers play in the spread of bovine TB since the cows can also pass the disease on to other members of the herd.
According to computer modelling studies, herd-to-herd transmission of bovine TB in cattle accounts for 94% of cases.
Scientific evidence from the randomised badger culling trials found around 6% of infected cattle catch TB directly from badgers.
The figure rises to about 50%, when cattle infected by badgers pass it on to other herds, say scientists.
Q: What are the costs of TB?
A: TB has cost the taxpayer in England £500m to control the disease in the last 10 years.
According to Defra, each pilot cull will cost about £100,000 a year, with these costs met by farmers who want badgers killed on their land.
This figure does not include policing costs, which have been estimated at £500,000 per area per year, according to a written answer to parliament.
According to Mary Creagh, shadow secretary of state for Environment, Food and Rural Affairs, other costs include:
- Over £300,000 for costs related to licensing the cull
- £750,000 for sett monitoring
- £17,000 for independent panel to monitor the cull
- £700,000 estimated costs for humaneness monitoring
- £750,000 for carrying out post mortems on badgers.
A wildlife charity has estimated the costs of the pilot culls to be more than £4,000 per badger killed.
Q: How are the badgers shot?
Most of the shooting was thought to have been carried out at dusk or at night, since the animals are largely nocturnal. There are two main methods used to shoot badgers: searching over an area with a spotlight and rifle; or placing bait at a fixed point, then lying in wait for the badger.
This requires a team of two or three people: the shooter, a spotter and a potential third person to drive a vehicle or act as an additional safety lookout.
Shooting must be avoided if the teams are near rights of ways, or close to rural dwellings in order to prevent accidental injury to the public.
To comply with humane standards, the person using the firearm must try to kill the animal quickly with the first shot. This means being able to locate the heart-lung area of the badger's body and be confident of a "clean" kill up to a range of 50-70m.
But there are problems in shooting animals at distance in the dark. Coloured filters can be used with spotlights to reduce a badger's awareness of the spotlight, allowing teams to approach more closely, or take more time on a shot. But they also reduce visibility for the shooter. Night vision sights can be used if certain conditions are met.
Officials accept that second shots may sometimes be necessary. Though it is practical to select a site near a badger sett, the shooting must not take place so close to the entrance (at least 30m away) that a wounded badger can retreat inside before a follow-up shot can be taken.
Licensed operators must pass a Defra-approved marksmanship course and must have received training on humane shooting. There are restrictions on firearms and ammunition.
Q: What is happening in Wales, Scotland and Northern Ireland?
A: Scotland is classified as free of TB. The Welsh Assembly Government has chosen to vaccinate badgers, with trials underway in North Pembrokeshire.
Northern Ireland is conducting research into an eradication programme involving vaccination and selected culling of badgers with signs of TB infection.
The Republic of Ireland has been culling badgers since the 1980s.
Q: Can badgers or cows be vaccinated?
A: There is a vaccine for badgers - the BCG jab, which has been used by a number of wildlife and conservation bodies in England, including the Gloucestershire Wildlife Trust, the RSPB, the Wildfowl and Wetlands Trust and the National Trust.
Badger vaccination is underway in Wales and the Republic of Ireland, and there are plans to introduce it in Northern Ireland.
Cattle can also be vaccinated with the BCG vaccine. Vaccination of cattle against TB is currently prohibited by EU legislation, mainly because BCG vaccination of cattle can interfere with the tuberculin skin test, the main diagnostic test for TB.
Vaccination is not effective in badgers or cattle that are infected with TB.
In Wales, the cost of vaccinating each badger is put at £662.