There's a difference between a full foundation of mortared and rebar-reinforced blocks and using a few stacked blocks at strategic points to support an outbuilding.
We're talking about a chicken coop. Cinder block Pier 3 or 4 high without mortar will hold a chicken coop easily, if placed correctly.P.S. To above recommendation, here are some Open Air coop builds:
https://www.backyardchickens.com/articles/jens-hens-a-southern-texas-coop.75707/
https://www.backyardchickens.com/articles/my-positive-local-action-coop.72804/
https://www.backyardchickens.com/articles/california-living.68130/