The increase in hawks is one reason, I have seen whole cotes emptied in days due to a hawk as fantails are easy picking for them. Basic rule the bigger the tail the easier they are to catch. We now have ones with a slight fan in the tail as they are better at flying and avoiding any predator
Nothing is foolproof as predators like hawks and cats will catch anything given the right opportunity, all you can do is cut down the risks
If you have a hawk, mainly sparrow hawk problem in your area then best not keep to ones in a cote, thankfully we don't have a problem as yet. We have only lost one to a sparrowhawk this year
Perigrines are not quite the same problem as fantails do not stray far from the cotes, and they tend to prey on flocks of pigeons
This is the type we have in our cotes, they are tame in the sense that they stay in our garden, we feed them, we vaccinate and worm them etc, but they are feral in the sense that they are free to all the elements, breeding and choosing mates etc
We have some on eggs but winter and nature will play a big part in the outcome, unlike the summer, they are very prolific :)