include a location filter in the checklist filter
If the checklist filter also filters by relevant location (e.g. the "Birds of Britain" checklist filtering your sightings for all species on the checklist seen at locations in the UK) then the totals in the checklist graph will be accurate. In this way you can use checklists to generate list totals for a given geographic area (and compare list totals between different checklists).
This is a bug that we intend to fix.
Great suggestion. Not sure why this wasn't done initially.