It is surprising to here that you feel that wildlife has moved away from an area with the sumac growth...given that staghorn sumac's flowers provide nectar for several butterfly species, leaves host various beneficial insects, fruits provide helpful late-winter food for many bird species, branches provide nesting sites for birds, and thickets offer shelter for wildlife.

That all being said, it is perfectly understandable to not want a certain native plant growing in a certain location on your property. 

The good news is that these plants are typically very shallow rooted, and you can rip them out with relative ease compared to other trees/shrubs. 

If site lines are your concern, you could also consider just periodically removing (or cutting down) the tallest stems to keep the whole plant shorter.

They are also of no harm to your soils or pond.