There's no way for us to allow for the 'when using app' Location Settings option as we require GPS at all times due to the bread crumb tracking feature of the application. The way Apple designed iOS, applications running in the background only have certain access to functions available in the OS, including access to GPS. There's no way for it to work without 'Always' being selected.
Another feature of the Duckr app is to upload your GPS coordinates on a schedule, so that in the event of an emergency, if a Duckr user presses the SOS button, any hunter in the immediate vicinity will also be notified to allow them to provide assistance. There is a also user option in Settings to enable sending your location when your battery life hits 2%, in case your phone dies during an emergency situation.