They are for entertainment and pest control. They stay on the ground and eat the bugs that might otherwise eat my plants. The adults are the size of a tennis ball, and the chicks when hatched are the size of bumble bees. You can easily hold a dozen chicks in your hand.
Here's a few pictures, hard to get any good ones because they are running around so quickly
I can't actually find a... sublemmy? named 'Plants', is there a more complete link you can provide?