Because they rejoice in God's creation and the expansion of natural habitats. There's a good human (and divine and natural) interest piece on today's Sioux Falls Argus Leader Sports page.
I post this as just one more corrective to the stereotype of hunters - and flyover country folks - as barbaric yahoos. The overwhelming majority of hunters are protective and reverent toward the created world. Most hunters know more about and interact more with the natural world than many urban "environmental" ideologues who lump hunting in with strip mining or toxic dumping.
There were two burials from our parish yesterday. Both were hunters and both were remembered thankfully by sons, daughters and grand kids for life lessons and blessed moments shared while hunting and fishing.
I can't find the quote but I think it was Thomas Jefferson who feared that urbanization would warp us, by depriving us of interaction with the natural cycles of life and death. Having grown up urban, I think that most hostility to hunting reflects a warped point of view.
Some might cite the near extinction of the buffalo here as an argument against hunting. But that was a machine-like campaign designed to destroy the Plains Tribes' main resource and ability to fight - more comparable to bombing factories and railroads than to hunting. For the Tribes, hunting was and remains an honored part of life.
In this Easter season, it is worth noting that Jesus attracted some of his first followers by guiding them to a big catch of fish (Luke 5), and then proved his Resurrection by showing up on a beach to grill up some fish they'd caught (John 21).