Hi,sorry for asking you guys again.recently, i heard there is a bird called eastern kingbird or Tyrannus tyrannus.Sorry if the writing is wrong,but i heard they are extremely aggresive bird that even have courage to fend off larger animal like eagle,cat,squirell,and raven.Is that really true?How big are they anyway?Thanks

I'm afraid I've no personal experience of these birds, but Wikipedia has a good lot of detail on them, which will tell you their size (35 cm wingspan):

http://en.wikipedia.org/wiki/Eastern_Kingbird


And you can see one in defensive posture against a much larger crow here:

http://www.youtube.com/watch?v=zYA2Q0-YYQM