His father registered Henry's birth on Dec 27, 1881. He may have reported the month of birth incorrectly. See the 1881 census which was to count individuals as of April 4th, which was prior to Henry's registered birth date.
Name: Henry Herbert Clark Date of Birth: 18 Apr 1881 Gender: Male Birth County or District: Simcoe Father's Name: Charles Clark Mother's Name: Levinia White Archive Name: Archives of Ontario Archive Series: MS929 Archive Reel: 51
Either this census was enumerated after Apr 18th, or Henry was born in March rather than April
Name: Henry Clarke Gender: Male Age: 1/12 Birth Year: 1881 Birthplace: Ontario Religion: Wesleyan Methodist Nationality: English Province: Ontario District Number: 139 District: Simcoe North Sub-District Number: A Subdistrict: Nottawasaga Division: 3 Household Members: Name Age Charles Clarke 29 Alvina Clarke 24 Henry Clarke 1/12
