The Wales boss has appointed Northampton fly-half Biggar to lead his country’s title defence, taking over from an injured Alun Wyn Jones.
Jones, the most-capped Test player in rugby union history, is among a number of high-profile absentees from Pivac’s 36-man squad for the tournament.
Jones’ fellow British and Irish Lions George North, Leigh Halfpenny, Ken Owens, Josh Navidi, Justin Tipuric and Taulupe Faletau also miss out due to injuries.
And Pivac has turned to Biggar, who has won 95 caps during a 13-year international career and started all three Lions Tests against South Africa last summer.
“We have lost 680 caps (to injury), and that is a lot of experience gone,” Pivac said. “Dan brings a wealth of experience, a wealth of experience in this competition.
“Also, we are looking at form, at players who are competing in different positions, and the captain has to have a guaranteed position in the team bolted on.
“Dan, at the moment, is the form 10, and there is a lot of competition in the other positions. We’ve gone with Dan. He brings that experience.
“I think it (captaincy) will add to Dan’s game.
“It is well-documented that Dan is a highly-motivated player, he is very competitive and he speaks his mind. We don’t want to change him as a competitive player.
“We want him to take on the role as a captain and the duties that go with that with referees.”
The squad includes three uncapped players in hooker Dewi Lake, his Ospreys colleague Jac Morgan and Cardiff number eight James Ratti.
Flanker Ross Moriarty who has not played since the autumn due to a shoulder problem, makes the group and is on course to feature for his regional team the Dragons a week before Wales’ February 5 Six Nations opener against Ireland in Dublin.
Pivac added: “We are in close contact with the clubs and their medical teams. Ross is on track to play, not this weekend as the Dragons don’t play, but the following weekend.
“He will be released from camp to get a game under his belt, and if he comes through that then obviously he will be available for selection for Ireland.”
Jones, meanwhile, has undergone two shoulder operations since being hurt during Wales’ Autumn Nations Series opener against New Zealand in October.
Hooker Owens has a back problem, Tipuric and Navidi have shoulder issues, North and Halfpenny are recovering from knee injuries and Faletau has not played this season because of ankle trouble.
When injuries are added to a number of coronavirus-related cancellations and postponements – the four Welsh regions have only played 17 games between them in eight weeks – it has been far from a straightforward Six Nations build-up.
“Preparing this squad is going to be the most challenging for us to date. Just selecting the squad was an interesting exercise,” Pivac said.
“It is well-documented with the Covid cases in clubs and being stuck in South Africa (as Cardiff and the Scarlets were), it hasn’t been ideal for a lot of players.
“I know they’ve been doing a lot of hard work behind the scenes, and we will be doing our best over the first few weeks to put as much volume into them as we can without breaking them.
“It’s a fine balance. We have got to get them up to playing Test rugby, and we know that takes a bit of work.
“Those players, through no fault of their own, have been put in that situation. So it is working together with the clubs, making sure we’ve got the right information about them in terms of the selection we have made, and we will see where we go from there.”
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