Brown moves to 5-17-1 overall and 2-13-1 in the ECAC, while Harvard dropped to 12-8-2 on the season and 8-6-2 in the conference play.
Ernst stopped 23 shots to earn the victory, while Steve Michalek made 22 stops for the Crimson. Senior Matt Lorito assisted on both of Brown's goals for the two-point effort. Brown picked up its fourth win against the Crimson in the past five meetings between the two teams.
"Honestly, the guys played the best game we've played all year," said head coach Brendan Whittet. "I thought we were tenacious in what we did and there were a lot of layers they had to go through. We just played a good hockey game and that's what I expect out of these guys."
The two teams were scoreless after the opening period, while Harvard held a slight edge in shots at 8-7. After Brown controlled the opening half of the period, Harvard came on late, but Ernst made a diving save to deny Seb Lloyd and the penalty kill unit killed off a late attack to preserve the 0-0 score.
Brown opened up the scoring just 1:03 into the second period when Bird recorded the first goal of his career. After Lorito launched a shot from the left circle that was turned away by Michalek, Bird quickly tapped in the rebound to give the home side the lead. Rookie Sam Lafferty also earned an assist on the play.
Brown struck again early in the third period as Nick Lappin notched his seventh goal of the season at 3:24. Fellow junior Mark Naclerio slid a centering pass to Lappin, who split a pair of Crimson skaters and sent an impressive backhanded shot past Michalek for the 2-0 advantage.
The Bears kept the Crimson at bay throughout the third period, but after Harvard pulled Michalek late in the contest, Desmond Bergin put the visitors on the board at 19:06 to trim the deficit to one. Nevertheless, Brown held off a late attack during final 50 seconds to secure the one-goal victory.