Zebra finches died after a week

Question
I was given a male and a female a week ago, they were in a cage about the size of a house brick but came from an Avery (outdoors) I have no idea about birds so I went out and got a big cage. I put an olive branch inside so they could sit on it and a little bamboo nest and they seemed happy. The male was quiet but the female was jumping all over the place and singing. The male slept a lot also! This morning I woke up and found the two of them on the floor dead, I feel really bad about it because I can only think I did something wrong! The one thing that I did different last night was light a joss stick! I've read on the net that air fresheners are toxic to birds and was wondering if this holds true for joss sticks? I want to get two more zebra finches but don't want to cause any harm to these little fellows! Do you have any sound advice about what not to give them food wise and what not to use near them? Thanks ever so much for any help you can offer me. Andy

Answer
I'm not sure what a joss stick but I know giving them branches or anything from outside without it being treated first is dangerous. I've never heard anything about air fresheners being dangerous though. What a lot of birds have is something called air sac mites. These are little mites that get into the throat and lungs of a finch and stay there. Eventually there are so many that the bird suffocates. This is very common for finches and easily treated once diagnosed. Should you decide to get more birds I will happy to tell you how to detect these mites and the best way to get rid of them