* Pep talks, encouragement for federal employees
* Worries about another possible shutdown threat next year
* National Zoo's Panda Cam returns, zoo to open Friday
By Deborah Zabarenko and Ian Simpson
WASHINGTON, Oct 17 (Reuters) - Furloughed U.S. government workers returned to their jobs on Thursday, greeted with doughnuts, coffee, pep talks from Obama administration bosses and anxiety over whether they will face another shutdown threat in the new year.
"I'm glad this whole thing is behind us and to be able to go back to work," Mike McParland, who works for USAID's Food for Peace program, said en route to his office. "I just hope they find a way forward before January so we don't have to go through this again."
Washington's renewed morning rush hour, the first after 16 days of government shutdown, came less than 12 hours after President Barack Obama signed a last-minute bill to fund the government through Jan. 15 and extend its borrowing authority through Feb. 7.
Vice President Joe Biden brought trans fat-free muffins to federal workers entering the Environmental Protection Agency, where about 94 percent of staff had been furloughed.
"These guys not only took a hit and ... (had) the anxiety of knowing whether they'd get back or paid," Biden said. "But now they're back, and they've got all that work piled up so they've got a lot to do so I'm not going to hold them up very long."
At the Agriculture Department, Secretary Tom Vilsack offered coffee and encouragement to returning employees, directing them to free doughnuts available inside the agency's massive building on Independence Avenue.
Most of the Pentagon's civilian employees returned to work, and heard from Defense Secretary Chuck Hagel in a statement.
"To those returning from furlough: know that the work you perform is incredibly valued by your military teammates and by me," Hagel wrote. "I appreciate your professionalism and your patience during this difficult period of time."
Treasury Secretary Jack Lew offered workers a similar message: "I know how difficult this was for staff who worked tirelessly during the shutdown ... (and) for everyone who wanted to be here to continue performing their duties with exceptional skill and dedication."
ANOTHER SHUTDOWN IN JANUARY? 'I HOPE NOT'
The U.S. World War II Memorial on Washington's central Mall, a flashpoint for anger over the forced closure of national monuments and parks, opened early on Thursday, as a park employee in hip boots waded into the fountain to clean it.
Robert Marimon, a 91-year-old retired electrical engineer and World War Two veteran from Avon Lake, Ohio, said this was his planned first stop on a U.S. capital visit, and he would have been disappointed if it had been closed.
"If it was closed, I was planning to try to get over the barriers one way or another," he said.
"I think it was pretty bad," Marimon said of the shutdown. "Personally, I think both parties, everybody, should have been able to get together way before this."
Asked about a possible repetition in January, he replied, "It sounds like it, but I hope not."
The U.S. Senate's 200-year-old Ohio Clock started ticking again on Thursday, wound for the first time since the shutdown began on Oct. 1. It froze in place at 12:14 p.m. on Oct. 9 because the specialists who normally wind it were among the 800,000 federal employees sent home.
Most of the Smithsonian Institution's museums and other facilities re-opened on Thursday, including the National Zoo's popular online Panda Cam, though traffic was so heavy that it took some doing to see it at. The zoo itself re-opens on Friday.