Is it legal for approx. 12 budgies to be kept in a 100cm/60cm/40cm cage?

As far as stocking densities go with pet birds, if you were to do this at home then it would be illegal, as they would be in there for about 10 years which isnt fair. But in a pet shop, they are in the cage for an extremely short amount of time compared to that 10 years, and so the stocking density can be higher. They are also cleaned every day, and fed at least twice a day so i wouldnt worry. This isnt cruel, its just that if they were to keep the birds in seperate cages, it would be completely unneccessary expense with food and cleaning, and would take up far too much space on the shop floor. But, if in doubt, ring your local RSPCA and just let them know of your concerns, they will visit, as all pet shops have regular RSPCA visits, and if there is a problem then they will work with the store to correct the problem