WJZ-TV (Channel 13) is still No. 1. But more and more Baltimore viewers are turning to WMAR-TV (Channel 2) for news at 5 p.m., according to the Nielsen audience survey for October.

The ratings, which were released yesterday, are the first scorecard on several key changes in the local TV news landscape this fall. The biggest involved WBAL-TV (Channel 11) canceling its 5 o'clock newscast in favor of "Golden Girls" reruns. Channel 11 was going for a larger audience with the entertainment programming, but according to the latest figures the sitcom did worse than the station's last-place newscast did a year ago, losing an estimated 18,000 TV households.

Channel 2, meanwhile, was the big winner at 5 o'clock. Sally Thorner and Stan Stovall saw their audience jump by about 37,000 TV homes from a year ago. Channel 2's early news is now watched in more homes than "The Golden Girls" on Channel 11 and reruns of "The Cosby Show" on Channel 13 combined.

At 6 p.m. and 11 p.m., when all affiliate newscasts go head to head, Channel 13 still wins handily. And Channel 13 dominates the early morning news block with more than half of all TV sets in use tuned to Marty Bass and Don Scott.

The "News at Ten" on WBFF-TV (Channel 45) was watched in about 19,000 TV homes. By way of comparison, Channel 13 drew 130,000 viewers at 11 p.m., followed by channels 2 and 11 with 74,000 each.

The only station willing to comment was Channel 2. "Obviously we're thrilled with the ratings and will continue to build on them," General Manager Arnold J. Kleiner said.