baykuşum / I am an owl
baykuştur / he, she, it is an owl
if you use the web version you have access to tips and notes where you can read about suffixes to express "to be"
"I am owl" is wrong in English because owl is countable and a determiner must be brought before the noun. In Turkish, it is not necessary to bring a determiner before a noun. However, when translating the sentence into English, bringing a determiner before a countable noun is a must. Of course, you don't want to destroy English, do you? :D
That's quite often the case I find. The reason given by the mod's is that the audio is computer-generated and so not always entirely accurate and they can do nothing about it. To view the problem in a positive light when listening to everyday speech in Turkey the words will not always be spoken clearly and as we develop our understanding of the language we'll be able to better pick up the clues and fill in the gaps in a sensible way.