I'm not entirely sure what you did. I think you probably aren't either.
What is the current state of your iCloud settings? What is turned on and what is turned off in iCloud? Please do NOT make any changes of any kinds at this time. Just tell me what it says. Also, what do you think it should say? What setting do you want?
The "bird" daemon is one of the iCloud tasks that runs in the background. It sounds like it is either trying to download a massive amount of data or delete a massive amount of data - or perhaps both.
Don't worry about the CPU usage. That is irrelevant. Instead, you should be worried about those documents that you didn't want deleted, which are now likely gone.
Do you know exactly which documents these were and where they were located? You can try to use the iCloud web interface at https://icloud.com and see if they still exist there. If they do exist, then you may have gotten lucky.
If they don't exist in iCloud.com, then I have to ask if you have a backup? It is an extraordinarily bad idea to not maintain a Time Machine backup.
Unfortunately, that's all I can tell you at this point because that's all I know.