The dovehawk is interesting. However, 20cm is... about 7-8 inches? And it's known to hunt pigeons and doves? If so, it's quite a bit more courageous than most raptors, to take on things so nearly its own size.
Also, a proofreading note: In the 2nd paragraph of the "Problems with dovehawks" section, "broaches" should be spelled "brooches." "Broaches" is when an aquatic animal breaks the surface of the water.