Report by ITV Wales' North Wales reporter Ian Lang
New measures for all poultry and captive birds will be introduced in Wales today, as the Welsh Government say there is a "heightened risk" of avian influenza this winter.
Farming experts say just a spoonful size of infected droppings could spread the disease to 10,000 other birds.
Bird keepers of all sizes in Wales have been urged by a farming union to "stay vigilant," as a string of rules have been implemented to combat the spread of the disease, more commonly known as bird flu.
From today, all birds must be kept indoors or otherwise separated from wild birds. Keepers must also carry out a "bespoke biosecurity review" of the premises where birds are kept to minimise the risk of the virus entering bird houses.
Some bird keepers have said they are welcoming the measures with the hopes it will protect their flocks from infection.
Watch: Llyr Jones says that he hopes the legal requirements, which came into force today, will bring more protection for his birds – and his livelihood in free-range eggs.
The Welsh Government say that its surveillance suggests avian flu is spreading westwards.
There have been five separate cases of H5N1 Avian Flu strain in Wales since the start of October, and the expert view is that there will be a heightened risk across Wales over the winter months.
The Welsh Government says that the risk to human health from the virus is "very low," and food standards bodies advise that avian influenzas also pose a "very low food safety risk".
Watch: NFU Cymru Policy Adviser, Dafydd Jarrett, says housing measures must also be accompanied by biosecurity measures to be effective.
NFU Cymru Poultry Board Chairman Richard Williams welcomed the new mandatory measures."These measures apply to all poultry keepers, whether you have one hen in the garden or a large poultry business, and I urge everyone to remain vigilant.
"This is a really challenging time for the Welsh poultry sector, but producers are doing all they can to protect their birds and to maintain production of healthy, nutritious and affordable poultry meat and eggs for our consumers to enjoy."