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A female Bufflehead swims across the Giacomini family’s stockpond next to my pasture last Friday.

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A male Greater Scaup paddles up Papermill Creek at White House Pool on Jan. 13.

West Marin’s waters provide winter havens for many thousands of ducks that summer further north. Ornithologist Rich Stallcup of Point Reyes Station, who helped identify these ducks, this week told me the “Greater Scaup does not nest in California, and only a few Buffleheads do.”

Buffleheads and Greater Scaups, Rich noted, “begin to arrive in West Marin in early October, and each species numbers well into the thousands on Tomales Bay during herring runs in late December and early January — at least 6,000 each. Most are gone by early April….

“Buffleheads are cavity-nesters and are expanding their breeding range aligned with the increased human interest in Wood Duck boxes, which Buffleheads will [likewise] occupy.

“Hooded Mergansers are similarly expanding their range,” Rich added. It’s one of the “side perks of Wood Duck-nestbox programs.”

Since 1955, the California Department of Fish and Game has annually made estimates — based on counts from the air — of how many breeding-age ducks are in their primary hangouts: “wetland and agricultural areas in northeastern California, throughout the Central Valley, the Suisun Marsh, and some coastal valleys.”

Weather greatly affects how many ducks nest in California. Two years ago, Fish and Game reported there were 615,000 ducks in their main nesting grounds, nearly a 50 percent increase from the year before, thanks to abundant spring rains that year. Approximately half the wild ducks in the state were mallards.

Fish and Game uses such estimates in regulating how many ducks hunters can bag in California each hunting season.

Last year, hunters nationwide shot approximately 16.6 million wild ducks, the Fund for Animals reports. That total is actually up slightly from figures half a century ago, as reported in The Encyclopedia Americana.

While Buffleheads and Greater Scaups are both hunted, roughly half the wild ducks shot in the US annually are mallards.