While an avocado can be a useful addition to a number of dishes for us humans, the same cannot be said for birds. You see, an avocado is like a giant piece of poison for a bird, so you would not exactly be helping it out by apparently giving it something to eat.
The reason why it is acting as a poison to a bird is because an avocado contains something called persin which is actually a toxin. However, it is a toxin that is perfectly harmless to us humans and we can eat them all day without it giving us any cause for concern. It is also true that dogs and cats appear to be immune to this poison as well, but sadly the same cannot be said for either birds or cattle where the toxin will attack their system and could prove to be deadly.