Reuters reports that March of the Penguins is now playing in 1,867 theaters in the United States and Canada this weekend, an usual number of theaters for a documentary.

The film, which follows a pack of Emperor Penguins during an arduous mating season, had grossed $18.4 million through Wednesday and was poised to surpass the $21.6 million for Michael Moore’s anti-gun documentary “Bowling For Columbine.”

Moore’s 2004 anti-Bush film “Fahrenheit 9/11″ is the No. 1 box-office documentary with $119 million. “Bowling for Columbine” ranks No. 2, excluding box-office figures for large-format Imax films and concert movies.

Brandon Gray, president of boxofficemojo.com, said “Penguins” probably would pass “Bowling for Columbine” by Friday.