Farnham makes a product called “JUST ONE BITE”.
Comes in a brick that is 1# and looks like peanut brittle.
I have lived rural for over 25 years, and dealt with Norway rats down to ground squirrels.
Brick should cost you about $7, but locally I can only buy it now in boxes of 8 bricks.
I place the unwrapped brick inside double Ziplock freezer bags, and pound it with a hammer on a hard surface. That breaks it up into pieces & crumbs.
Put those items where the squirrels run, even in the crotch of a tree. Keep way from your pets.
You should be finding dead squirrels within 3 days.
Only prob I have with BAITS is I like the giant owls and hawks, they eat a baited chippy or Squril then there dead.
I let everyone do there own thing with out the intervention of poison, and I play defense best I can
That’s the way to kill all the raptors and other squirrel predators in half the county.
And damn irresponsible eradication.