FERNLEY, Nev.—Behind the piles of smiley-faced Amazon.com Inc. boxes arriving on doorsteps this holiday season are workers like Ray and Sarann Williams.
The retired couple are part of the swarm of seasonal employees taking up temporary residence in this small desert city—home to one of Amazon's warehouses—to help the online-retail giant fulfill its influx of holiday orders.
The Williamses migrated from their home in Hurricane, Utah, to take the two-month warehouse gig. "The money always helps" and the physical labor "always makes me feel better," Mr. Williams said as he walked his miniature schnauzer, Maya, around the Desert Rose RV park, where the couple is currently residing. The 75-year-old said this was his second stint as a seasonal Amazon worker, after spending last autumn at Amazon's Campbellsville, Ky., location.
Amazon, the world's biggest e-commerce purveyor, sees a sales spike every fourth quarter, when it makes nearly 40% of its more than $34 billion in annual revenue. To meet that surge, the Seattle-based company hires hundreds of temporary workers at each of its 34 U.S. warehouses.
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A spokeswoman for Amazon, which has 51,000 staffers excluding seasonal workers world-wide, said it hires "thousands" of temporary workers for the holidays, but declined to disclose specific numbers. It said it quadrupled its staff at its warehouse in Phoenix to 1,200 to handle the end-of-year rush.
Many of these employees belong to the community of "workampers," a sort of modern-day migrant worker. Many of them are retirees who spend all or part of the year living in RVs and taking odd seasonal jobs around the country. While some workers really need the money, others said they take the gigs to help fund their adventures or just for fun.
Many current and former seasonal workers said Amazon pays decent wages—about $12 an hour plus overtime in Fernley, which is about 50% better than minimum wage here. But that is in exchange for long hours and tedious labor.
"It's like the best place to work and the worst place to work," said Kelly Andrus, a 50-year-old Fernley resident who served as an Amazon holiday employee seven years ago. "It's good pay, and they're safety oriented," but she said the managers were strict and the labor was physically demanding.
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Workers can be on their feet for hours fetching items from shelves, packing boxes and preparing incoming items for storage. Many said they lose five pounds or more in a few weeks. Earlier this year, Amazon was on the defensive after an Allentown, Pa., newspaper reported that more than a dozen workers collapsed inside the local warehouse there because of the summer heat. The company said employee safety was its top concern and that it had urgently installed air conditioning.
Holiday hiring surges are common in online retailing. At online electronics retailer Newegg Inc., a spokeswoman said the company boosts warehouse and customer-service headcount by about 130, or roughly 20%, during the holidays.
Amazon finds its workers via recruiting events, such as the one it held at an RV show in Quartzsite, Ariz., earlier this year. Many also come by word of mouth.
Clare Moxley, who came to Fernley from Kimberley, British Columbia, said she heard about the Amazon gig from a workamper website. The 54-year-old went into early retirement five years ago, after working as a bank information-technology manager, and said she recently took up the RV lifestyle to battle complacency.
Though she sometimes gets together with several coworkers at a local Mexican restaurant on Saturdays, Ms. Moxley said most nights she is too tired to do anything but stay in her 16-foot trailer, which has room only for a small desk and a twin-sized bed. Off days are used to catch up on sleep and to do laundry.
Still, she said she was glad to make new friends in Fernley and to prove that she could still handle tough labor.
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"I definitely would do it again," Ms. Moxley said.
Amazon said it hires RV residents for the autumn in three locations, Fernley, Campbellsville and Coffeyville, Kan., as part of a program called CamperForce, which started last year.
Current and former seasonal workers said Amazon lets them choose from several RV camps where the retailer will pay the parking fee for the seasonal workers.
Each location is distinct. The Desert Rose RV Park in Fernley sits off a highway in the arid desert. Occupants of the 90 campers hang out in the communal laundry and recreation room, where they threw a small, informal holiday party Wednesday. Cherie Ve Ard and Chris Dunphy said they stayed at scenic Elk City State Park when they worked at the Coffeyville location in 2009.
The influx of Amazon's holiday help can perk up places such as Fernley, a city of 19,000 about 45 miles east of the California border, where the online retailer opened its warehouse in 1999. Restaurants and casinos get crowded. There are traffic jams.
"There's probably more people working in Fernley at this time of year than any other," said Eric Stanger, president of the local Chamber of Commerce.
Amazon's Fernley warehouse, which is about the size of 13 football fields, sits between the stores of two competitors, Wal-Mart Stores Inc. and Lowe's Cos. Employees say they often park in the lots of those big-box retailers when the Amazon lot fills up. The area gets congested around 6 p.m., when the shifts change.
The RV parks are perhaps Amazon's biggest beneficiaries this time of year. Debbie Skinner, the owner of Desert Rose RV Park, said about a fifth of her annual revenue—she wouldn't give underlying numbers—comes from Amazon. The monthly parking rate at Desert Rose is $375, though Ms. Skinner would not disclose Amazon's special rate.
The effects of temporary help also trickle down to local businesses and the city government. Troy Sibson, manager of Pioneer Crossing Casino, said his establishment gets noticeably busier during these months.
Mr. Sibson couldn't provide specific figures on the boost from seasonal workers. But he noted one change: "They befriend the bartenders."
Write to Stu Woo at Stu.Woo@wsj.com