By Theopolis Waters and Heiwon Shin

CHICAGO (Reuters) - U.S. consumers can expect to spend less on their traditional Thanksgiving and Christmas turkeys and hams this year as supplies of both have rebounded from outbreaks of avian flu and a pig virus that hit production.

In 2015, an outbreak of avian flu hit poultry flocks and 7.7 million turkeys were culled. Two years earlier, the hog population was hit by porcine epidemic diarrhea virus (PEDv), and roughly 8 million pigs were killed.

Hog farmers have revived herd sizes so successfully that the United States had a record 70.9 million head as of Sept. 1, according to the U.S. Department of Agriculture (USDA).

Turkey meat supplies dropped about 2 percent last year to 5.63 billion pounds, according to the USDA, due to one of the worst bird flu outbreaks the country has ever had. This year, turkey meat production is expected to rebound to 6.06 billion pounds - the first year-over-year growth since 2012.

"Supply has come back fully with production up over last year. And from a whole bird stand point, specifically for the holidays, there is sufficient product out there," Jay Jandrain, executive vice-president of sales for Butterball, told Reuters.

Butterball, jointly owned by Seaboard Corporation <SEB.A> and Maxwell Farms, is the biggest turkey producer in the United States and accounts for about a third of all the whole birds purchased in the country during the holiday season.

Americans eat their way through some 46 million turkeys at Thanksgiving and 22 million during the Christmas holiday.

This year, cheaper birds should help reduce the cost of a traditional Thanksgiving Day spread for 10 people to $49.87 from last year's $50.11 record, according to the American Farm Bureau Federation (AFBF).

A 16-pound turkey this year averages $22.74, a decrease of 30 cents from 2015, AFBF director of market intelligence John Newton told Reuters.

The AFBF has been conducting its survey of Thanksgiving meal costs for 31 years, asking nearly 150 volunteer bargain hunters in 48 states for a price that tallies up staples such as cranberries, pumpkin pie, sweet potatoes and all the trimmings.

For ham, the USDA's monthly retail meat data issued on Thursday showed boneless hams at $4.05 per pound in October, down from $4.23 a year ago.

"It is advantageous in pricing thanks to the record hog production this year," Patrick Fleming, director of market intelligence and innovation at the National Pork Board, told Reuters.

(Editing by Jo Winterbottom and David Gregorio)