How much has duck hunting changed in Minnesota in the past century?

Consider: At one time, the number of scaup — bluebills — killed by Minnesota waterfowlers in Otter Tail County alone exceeded the total number of ducks felled during an entire season in the Atlantic Flyway.

As recently as 1949 Minnesota waterfowlers bagged 559,000 bluebills — a harvest number that in the years since has inexorably declined to the point where, last year, barely 14,000 of these fast diving ducks were felled in the state.

So prominent a place in the state's waterfowling lore did bluebills once possess that entire hunting camps were built to focus specifically on them.

From Delta March in Manitoba south along the bluebill's migratory path to Lake of the Woods, then Thief Lake, Leech Lake, Winnibigoshish and Pelican lakes, among others, big-water duck hunters gathered to intercept a diving-duck species they ranked above even the storied canvasback.

So what happened to this duck that so many Minnesotans held dear?

Certainly, its continental breeding population has declined, from a long-term springtime average of about 5 million to about 3.6 million today. But 3.6 million is still a lot of ducks — only 3.3 million gadwall, for example, were counted continentwide this spring.

"It's hard to figure out why scaup don't migrate through Minnesota in the numbers they once did in part because we don't know why they were here in such great numbers in the first place,'' said Steve Cordts, Minnesota Department of Natural Resources waterfowl specialist.

Certainly, the state has far fewer wetlands than it did in 1949. Assured as well is that many wetlands and other waters that remain in Minnesota are degraded and don't produce the vegetation or support the number of aquatic invertebrates such as freshwater shrimp they once did.

Still, given the number of scaup that still exist in North America, it's a mystery why so few now visit Minnesota in October.

A mystery as well is the corresponding rise, during the scaup's downfall, of the ring-necked duck — a waterfowl species that, superficially at least, would seem to be, if not a sibling, at least a distant cousin of the scaup.

Yet historically, "ringnecks'' were a no-show in Minnesota, barely registering among ducks that nested in or migrated through the state.

"You can look at old duck hunting photos from Minnesota from the 1900s to the 1950s, and you can't find a single ringneck,'' Cordts said.

But now, depending on the year, ringnecks are either the third- or fourth-most abundant duck in state waterfowlers' bags.

Similar in size (1.8 pounds for lesser scaup vs. 1.6 pounds for ringnecks), the two ducks also share a common appearance, except that, paradoxically, the ringneck has a prominent ring around its bill (thus earning the name "ringbill'' among some hunters), and the bluebill doesn't.

Additionally, the speculum on the wing of the ringneck is gray, while the bluebill's speculum is white.

"Another difference is that the ringneck is an October bird,'' Cordts said. "They're almost all gone from Minnesota by Nov. 1, whereas bluebills often are still migrating through the state in November.''

Additionally, bluebills, being big-water ducks, often prefer during their migrations to raft up by the hundreds or even thousands on large lakes. By contrast, ringnecks generally like smaller and boggier environments, and relish especially lakes and rivers where wild rice grows.

That said, it's also true that in some years perhaps half of the continent's entire ringneck population migrates through Minnesota, staging, predominantly, as they do at Nett Lake, Drumbeater Lake and Rice Lake National Wildlife Refuge.

Fortunately for hunters, while approaching decoys, neither bluebills nor ringnecks are considered particularly wary, especially if the decoys are of their own species. Also, both can be seduced by calling, but not as consistently as dabbling ducks such as mallards.

And as table fare?

Both are good, most northern hunters agree.

Down south, however, bluebills and ringnecks often are the primary ingredients in a gumbo, where their late-season gamy taste can be folded into a properly made roux and blended with andouille sausage and multiple cloves of garlic, rather than featured as a table's main attraction.