Magpies can have black bills, while Anaconas barely can even get black bills some can, But it's not as common as yellow and orange, Anacondas also get black spots on their sides and magpies majority of the time get it on their wings and back this is a picture I found on google of an anacona
In some cases, They have black bills or dark brown bills But now That I've looked at some pictures, It looks like he's a magpie! Probably not an Appleyard.. Sad.. :(
What an adorable little guy :love It is probably an Appleyard or magpie. Appleyard, I bet on the most but the chances of magpie is still good! Thank you for taking care of him:)