The new girls

Today was the monthly market in Saintes, so we bought some new girls to restock the hen house after last month's slaughter. Some friends of ours wanted to buy us a chicken, specified it must be a brown one and we were to call it Rosie, so we bought one brown and four new black ones.
One black hen is very black, with greyish legs, whereas the other three have touches of brown feathers mainly on their necks and they have yellowish feet and legs. One looks several weeks younger than the others, so already they have their own separate identities, but they haven't had much interaction with the original three yet as those girls made a fuss and shouted to be let out into the garden as soon as we got home with the new girls!

UPDATE: the five timid new girls soon found their feet and two of them escaped, going on the run for a few hours at the other end of the garden. Then all five refused to go to bed, so we had to round them up individually and lift them onto their perches before we could lock them safely in. What have we done?