In "real" old-time Cajun culture, the protein-type ingredients in jambalaya and gumbo would vary seasonally: shrimp right around this time of year, crawfish in the spring, oysters in months with (or without?) an "R" in their names, poultry and smoked meat products (sausage) year 'round, but especially after the harvest and through the winter.

I've heard that the best substitute for andouille in places where it's unavailable is Polish sausage ~ kielbasa.

Duck is a fairly common Cajun-food ingredient; rabbit, too. Those are a couple of "wild game" meats that you'll occasionally find in restaurants. If you want squirrel or nutria in your jamabalaya, however, you'll have to find your way into someone's home kitchen.