Shoppers have begun seeing stickers appearing on free range egg boxes, announcing that the hens who laid the eggs have actually been kept temporarily in barns for their welfare.
So what are the rules around the free range status - and what do recent changes mean for farmers and consumers?
There are four different types of eggs sold in the UK, all of which are stamped on the carton for you to see: organic, free range, barn-reared, and caged.
To be classed as a free range egg, the hen laying it must have had unlimited daytime access to runs with vegetation and at least four square metres of outside space per bird.
The hens are then kept in barns with bedding and perches overnight, with nine birds allowed per square metre.
But they are now spending all day indoors?
Towards the end of 2016, there was an outbreak of avian flu - or bird flu - across Europe.
Farmers hoped it would never make it to British shores, but in December the H5N8 strain of the disease was found in some wild and farmed birds in the UK.
As a result, on 6 December the government's Department for Environment, Food and Rural Affairs (Defra) issued a prevention zone order in England, making farmers keep their birds inside to stop the spread of the disease. Similar restrictions were introduced in Scotland and Wales.
After the flocks were taken indoors, companies selling the eggs started to put stickers onto their products or put up signs in shops to let people know animals were being "temporarily housed" during the outbreak.
Can the eggs still be called free range?
Rules from the European Commission (EC) state that after 12 weeks of hens being housed indoors, their eggs cannot be marketed as "free range" and instead would become "barn-reared".
The current Defra order runs until 28 February, after which the majority of farmers are expected to be allowed to let their hens back out.Image caption Some shops, including Co-op, are putting up signs to tell customers about the rules
But for farmers forced to continue following the order after this date, they will not be able to call their eggs free range any more.
For now, the stickers and signs are within regulations, but the situation has been described as "fluid" by retailers and it is uncertain how long stickers can be used after the end of the month, instead of full package redesigns.
Will they taste different?
There is much debate in the industry as to whether free range eggs taste any different to those from caged or barn-reared hens.
While high-profile chefs like Jamie Oliver and Hugh Fearnley-Whittingstall sing the praises of letting hens loose around the farm, taste inevitably remains subjective.
But, if you have any worries about the safety of the eggs during the avian flu outbreak, don't panic - both the government and producers have said there are no health concerns.
Will the eggs cost the same?
Retailers have told the BBC that the prices - up to twice as much as caged hens' eggs - will remain the same for now.
A spokesman for Sainsbury's said the cost to their suppliers would not change, so prices would stay put to support them - although the supermarket expects few of its suppliers to continue to be affected after the end of the month.
But farmers know they cannot continue to charge a premium forever if their hens stay indoors.
President of the National Farmers Union Meurig Raymond has written to the CEOs of Britain's top 10 retailers thanking them for their support, including installing in-store signs and flagging the issues up on their websites.
But he warned of potentially "huge impact" on the sector.Image caption Places that sell products containing eggs, including Boots, are also putting up signs
"These are unprecedented times," he said. "I remain very concerned about the future of the free range poultry sector for both meat and egg products should the housing order remain in place without a derogation that enables producers to market those eggs and meat to market as free range."
The National Farmers Union is lobbying the EC to extend the 12-week rule for calling eggs free range as producers worry about the hit their business will take if prices are forced down.
But a blog post for the Ranger by Mark Williams, chief executive of the British Egg Industry Council, said lobbying of the Commission was not proving fruitful.
"We have built a strong coalition of member states, MEPs and industries, but our calls for an immediate and practical solution are falling on deaf ears in the Commission," he wrote.
"We continue to apply pressure at the highest possible level and are already looking at future solutions."
According to the Daily Mail, farmers in Holland are already in the process of re-labelling free range eggs and poultry after losing an appeal against the EU to extend the 12-week rule.
So when can farmers let hens be free range again?
That is still not certain.
A spokeswoman for Defra said it expected about 75% of farms would be allowed to let their birds back out by the end of February deadline, although they would still have to stick to extra biosecurity measures, including fencing off ponds, to stay safe.
Chief veterinary officer Nigel Gibbens said: "Bird flu is also transmitted via the environment, for example in wild bird droppings, and it is vital that keepers practise strict biosecurity.
"This means taking precautions such as putting up netting, keeping food and water inside and disinfecting footwear and equipment after contact with birds."
But there is still concern about avian flu in high-risk areas.
This means Defra will be moving to a "targeted approach", keeping the rules in place for the other quarter of farms still deemed at risk - thereby affecting some producers' claims to free range status.
Some smaller farms will be able to allow hens outside under netting, meaning their eggs can be classed as free range.
However, for larger operations, this just won't be an option.