A vacancy in the council, whether it be in the office of mayor or alderman, shall be deemed to exist in case of the failure of any person elected thereto to qualify on or before the date of the second regular meeting of the new council, or by reason of the death, resignation, removal from office, removal from the City, continuous absence from the City for more than three months, or conviction of a felony of any such person after his election, or by reason of the failure of any councilman without good cause to perform any of the duties of membership in the council for a period of three months. In each such case the council shall by resolution declare such vacancy to exist and shall forthwith appoint an eligible person to fill the same until the next regular municipal election, when the office shall be filled for the unexpired term. In the event an alderman moves his residence from the ward from which he was elected to another ward within the City, no vacancy shall be deemed to exist until the next regular City election, at which time the office shall be filled for the unexpired term. Nor shall a change in ward boundaries as herein provided in anyway affect the then current term of any alderman. However, a candidate for election or re-election to the office of alderman must be a bona fide resident of the ward from which he seeks election and meet all other requirements of such candidacy.