A 30-year-old duck hunter who was trapped in his boat overnight was plucked Wednesday morning from the muddy waters near the Alviso Marina by a helicopter.

The man was rescued at 4:36 a.m. when a Calstar helicopter landed in a marsh area, according to San Jose fire Capt. Mary Gutierrez. The man was taken by ambulance to a hospital after spending the night in freezing conditions.

Authorities did not identify the man, a war veteran who served in Afghanistan. He had spent Tuesday hunting and fishing in a small fiberglass motor boat, according to fire officials. When he did not return home, his family grew concerned and called police at about 9 p.m., according to fire Capt. Anthony Melendez.

Police located the man's vehicle in the Alviso Marina County Park parking lot and then called for a search and rescue party.

The Santa Clara County Sheriff's Office sent its helicopter to help in the search. However, the helicopter had mechanical issues and returned to its base at Moffett Field. A U.S. Coast Guard helicopter was then called in and after about a one-hour search also suffered mechanical trouble.

At that point search and rescue officials called Calstar, a private company, use one of its helicopter in the search.

The Calstar helicopter spotted the man about 3¿1/2 miles from the marina and landed in a muddy marsh area, Melendez said. The man walked through knee-deep mud to the helicopter and was taken to the parking lot, where an ambulance was waiting.

The man had a poncho but otherwise was not wearing a lot of warm clothing, Melendez said. Overnight temperatures dropped to 34 degrees.

"It was like finding a needle in a haystack," Melendrez said. "He had no flares. He had nothing with him. He was fortunate that it ended with good news."

Contact Mark Gomez at 408-920-5869. Follow him on Twitter @MarkMGomez