References 

I've started providing references.
 Terms I tagged "dubious" may be deleted, as far as I am concerned. But do pay attention to the information I've added here and there in remark tags.
 Terms I tagged "citation needed" I hope other editors will be able to find a source for. I ask other editors to refrain from deleting them for at least a month, and preferably actively help out in finding sources.   

Would you say  http://www.britishbirdlovers.co.uk/articles/collective-nouns-for-birds.html is a reliable source? I doubt it.

The terms sourced from The Free Dictionary are from the Book of St. Albans (attributed to Dame Juliana Barnes, 1486). This site also brings them, and adds "Many of these are fanciful or humorous terms which probably never had any real currency. (Taken from the Concise Oxford Dictionary)". Do you think these terms belong in this article?