The Boy Scouts of America experienced a modest dip in membership in 2013, but not the mass exodus that some social conservatives predicted while it was considering changing its membership policy on gays.

Boy Scouts membership fell by 6 percent last year, leaving it with nearly 2.5 million youth members and 960,000 adult members.

Reasons for the attrition, which is slightly greater than the 4 percent losses in 2012 and similar-sized declines in several previous years, are not fully understood but are likely related to the divisive vote on admitting openly gay youths to Scouts as well as a 60 percent increase in annual membership dues.

It’s “impossible to point to any single factor that influences our membership numbers,” Deron Smith, director of communications for Boy Scouts of America, said Wednesday.

But on social media sites the May vote on gay youths has been cited as a factor, and Trail Life USA, a Christian-based, outdoor, character-building group for boys and young men, says Boy Scout defectors are driving its quick growth.