As long as they have a dry, draft free place, they can withstand extreme cold weather. Most pheasants prefer to roost on the ground or on perches as high above the ground as they can get or is available in your enclosure.
It's one of many of the True pheasants, a Southern Green pheasant or (Phasianus versicolor versicolor). They are endemic to Japan.
Also in the group is P. versicolor tanensis or Pacific Green pheasant and P. versicolor robustipes or Northern Green pheasant.
The last bird is a P.c. straunhi or...
Howdy
I don't know the "laws" or regulations in the UK but here in the USA, what you did is illegal. That being put aside, pheasants should not be raised with other poultry, especially chickens. Chickens carry diseases that they can tolerate but will kill a pheasant and other gameirds.
They...