While of course it's possible they may have originally come from Bristol, I'm fairly sure this pair arrived at the zoo in 2018/2019, so it likely doesn't have anything to do with Bristol's recent closure.
@Benosaurus Thank you for your answer. I only suggested this because Bristol was the only place I have seen the species recently, but I find that I photographed them in the flamingo pen there in 2012, although I don't think I saw them in my last visits before closure. They may be at Wild Place or gone elsewhere.