ive even heard of fantails killed in the night and during day, but rats, shrews, least weasels, etc. cats and peregrines are like stealth ninja. if your birds are white, even worse as fantails and rollers, especially white, are the most tempting and attracting of attention of raptors and all predators in general, but make best droppers, and most common for both. maybe let them raise at least two to four batches, and breed those babies of theirs to something else to make garden fantails to fly (even ferals, homers or rollers). i have one Capuchin and one fantail mix female, both white, and they attract the attention of the hawks since letting out like crazy. luckily i have male other performing types that take up and distract the hawks, confusing them seeming more than anything, that and they go behind a clear pane and the hawks just whack into it and dont come back more than a second time each. also now i have by advice only let them out in afternoon to preferably evening, as a lot less to no hawks still hunting (though a couple owls now).