Well, because Silas has asked—

"Aside from the milk, they've a taste for weeds. It'd save me some time to have one clearing those when spring comes."

There's some amusement in a look Ellis directs across to Silas as he stirs the pot, observing the contents before he continues, "Are you developing an interest in farm animals?"

A signal that Ellis is happy to lay out his ideal plan for the ecosystem he's establishing in Wysteria's back yard, if Silas leaves room for it.