You even have to report if you have been to, or work on a farm, or work with animals at customs to enter the country. They want to make sure you haven't brought any viruses, etc. in on your shoes or person. As a (very large) island they have to be very careful because foreign germs/viruses can be spread easily. Last time I was there I had to report that I worked with endangered cats. They decided that working with tigers, leopards and such didn't pose a threat since they have no wild cats in Oz.
