Squirrels Plant Avocado Pits. Some turn into trees. Squirrels locate avocados and drop them to the community below him or her [I think it's a him, but statistics would show a balance I presume].

Squirrels plant avocado trees after human planted the first one.  We get hundreds of avocados from the one original tree.  If it wasn't for space constraints, many more could have been bearing fruit. e.g. James Comey can still sell to libraries, friends of friends and collectors.